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id="toc-NASA's_Reduced_Gravity_Aircraft" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#NASA's_Reduced_Gravity_Aircraft"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1.1</span> <span>NASA's Reduced Gravity Aircraft</span> </div> </a> <ul id="toc-NASA's_Reduced_Gravity_Aircraft-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-European_Space_Agency_A310_Zero-G" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#European_Space_Agency_A310_Zero-G"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1.2</span> <span>European Space Agency A310 Zero-G</span> </div> </a> <ul id="toc-European_Space_Agency_A310_Zero-G-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Commercial_flights_for_public_passengers" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Commercial_flights_for_public_passengers"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1.3</span> <span>Commercial flights for public passengers</span> </div> </a> <ul id="toc-Commercial_flights_for_public_passengers-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Ground-based_drop_facilities" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Ground-based_drop_facilities"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Ground-based drop facilities</span> </div> </a> <ul id="toc-Ground-based_drop_facilities-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Random_Positioning_Machines" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Random_Positioning_Machines"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Random Positioning Machines</span> </div> </a> <ul id="toc-Random_Positioning_Machines-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Neutral_buoyancy" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Neutral_buoyancy"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.4</span> <span>Neutral buoyancy</span> </div> </a> <ul id="toc-Neutral_buoyancy-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Orbits" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Orbits"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5</span> <span>Orbits</span> </div> </a> <ul id="toc-Orbits-sublist" class="vector-toc-list"> <li id="toc-Sub-Orbital_flights" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Sub-Orbital_flights"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5.1</span> <span>Sub-Orbital flights</span> </div> </a> <ul id="toc-Sub-Orbital_flights-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Orbital_Motion" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Orbital_Motion"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5.2</span> <span>Orbital Motion</span> </div> </a> <ul id="toc-Orbital_Motion-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Weightlessness_at_the_center_of_a_planet" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Weightlessness_at_the_center_of_a_planet"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.6</span> <span>Weightlessness at the center of a planet</span> </div> </a> <ul id="toc-Weightlessness_at_the_center_of_a_planet-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Absence_of_gravity" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Absence_of_gravity"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Absence of gravity</span> </div> </a> <ul id="toc-Absence_of_gravity-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Health_effects" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Health_effects"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Health effects</span> </div> </a> <button aria-controls="toc-Health_effects-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Health effects subsection</span> </button> <ul id="toc-Health_effects-sublist" class="vector-toc-list"> <li id="toc-Space_motion_sickness" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Space_motion_sickness"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Space motion sickness</span> </div> </a> <ul id="toc-Space_motion_sickness-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Musculoskeletal_effects" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Musculoskeletal_effects"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.2</span> <span>Musculoskeletal effects</span> </div> </a> <ul id="toc-Musculoskeletal_effects-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Cardiovascular_effects" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Cardiovascular_effects"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.3</span> <span>Cardiovascular effects</span> </div> </a> <ul id="toc-Cardiovascular_effects-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Effects_on_non-human_organisms" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Effects_on_non-human_organisms"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.4</span> <span>Effects on non-human organisms</span> </div> </a> <ul id="toc-Effects_on_non-human_organisms-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Commercial_applications" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Commercial_applications"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Commercial applications</span> </div> </a> <button aria-controls="toc-Commercial_applications-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Commercial applications subsection</span> </button> <ul id="toc-Commercial_applications-sublist" class="vector-toc-list"> <li id="toc-High-quality_crystals" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#High-quality_crystals"> <div class="vector-toc-text"> <span class="vector-toc-numb">5.1</span> <span>High-quality crystals</span> </div> </a> <ul id="toc-High-quality_crystals-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Table of Contents" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Weightlessness</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 50 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-50" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">50 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Gewigloosheid" title="Gewigloosheid – Afrikaans" lang="af" hreflang="af" data-title="Gewigloosheid" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%A7%D9%86%D8%B9%D8%AF%D8%A7%D9%85_%D8%A7%D9%84%D9%88%D8%B2%D9%86" title="انعدام الوزن – Arabic" lang="ar" hreflang="ar" data-title="انعدام الوزن" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/%C3%87%C9%99kisizlik" title="Çəkisizlik – Azerbaijani" lang="az" hreflang="az" data-title="Çəkisizlik" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%93%E0%A6%9C%E0%A6%A8%E0%A6%B9%E0%A7%80%E0%A6%A8%E0%A6%A4%E0%A6%BE" title="ওজনহীনতা – Bangla" lang="bn" hreflang="bn" data-title="ওজনহীনতা" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%91%D1%8F%D0%B7%D0%B2%D0%B0%D0%B6%D0%BA%D0%B0%D1%81%D1%86%D1%8C" title="Бязважкасць – Belarusian" lang="be" hreflang="be" data-title="Бязважкасць" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%91%D0%B5%D0%B7%D1%82%D0%B5%D0%B3%D0%BB%D0%BE%D0%B2%D0%BD%D0%BE%D1%81%D1%82" title="Безтегловност – Bulgarian" lang="bg" hreflang="bg" data-title="Безтегловност" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Ingravidesa" title="Ingravidesa – Catalan" lang="ca" hreflang="ca" data-title="Ingravidesa" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cv mw-list-item"><a href="https://cv.wikipedia.org/wiki/%D0%99%D1%8B%D0%B2%C4%83%D1%80%C4%83%D1%88%D1%81%C4%83%D1%80%D0%BB%C4%83%D1%85" title="Йывăрăшсăрлăх – Chuvash" lang="cv" hreflang="cv" data-title="Йывăрăшсăрлăх" data-language-autonym="Чӑвашла" data-language-local-name="Chuvash" class="interlanguage-link-target"><span>Чӑвашла</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Stav_bezt%C3%AD%C5%BEe" title="Stav beztíže – Czech" lang="cs" hreflang="cs" data-title="Stav beztíže" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/V%C3%A6gtl%C3%B8shed" title="Vægtløshed – Danish" lang="da" hreflang="da" data-title="Vægtløshed" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Schwerelosigkeit" title="Schwerelosigkeit – German" lang="de" hreflang="de" data-title="Schwerelosigkeit" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Kaalutus" title="Kaalutus – Estonian" lang="et" hreflang="et" data-title="Kaalutus" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Ingravidez" title="Ingravidez – Spanish" lang="es" hreflang="es" data-title="Ingravidez" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A8%DB%8C%E2%80%8C%D9%88%D8%B2%D9%86%DB%8C" title="بی‌وزنی – Persian" lang="fa" hreflang="fa" data-title="بی‌وزنی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Apesanteur" title="Apesanteur – French" lang="fr" hreflang="fr" data-title="Apesanteur" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/D%C3%ADmhe%C3%A1chan" title="Dímheáchan – Irish" lang="ga" hreflang="ga" data-title="Dímheáchan" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Ingravidez" title="Ingravidez – Galician" lang="gl" hreflang="gl" data-title="Ingravidez" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EB%AC%B4%EC%A4%91%EB%9F%89%EC%83%81%ED%83%9C" title="무중량상태 – Korean" lang="ko" hreflang="ko" data-title="무중량상태" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D4%B1%D5%B6%D5%AF%D5%B7%D5%BC%D5%B8%D6%82%D5%A9%D5%B5%D5%B8%D6%82%D5%B6" title="Անկշռություն – Armenian" lang="hy" hreflang="hy" data-title="Անկշռություն" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Beste%C5%BEinsko_stanje" title="Bestežinsko stanje – Croatian" lang="hr" hreflang="hr" data-title="Bestežinsko stanje" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Tanpa_beban" title="Tanpa beban – Indonesian" lang="id" hreflang="id" data-title="Tanpa beban" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Assenza_di_peso" title="Assenza di peso – Italian" lang="it" hreflang="it" data-title="Assenza di peso" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%97%D7%95%D7%A1%D7%A8_%D7%9E%D7%A9%D7%A7%D7%9C" title="חוסר משקל – Hebrew" lang="he" hreflang="he" data-title="חוסר משקל" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%A1%D0%B0%D0%BB%D0%BC%D0%B0%D2%9B%D1%81%D1%8B%D0%B7%D0%B4%D1%8B%D2%9B" title="Салмақсыздық – Kazakh" lang="kk" hreflang="kk" data-title="Салмақсыздық" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-ht mw-list-item"><a href="https://ht.wikipedia.org/wiki/Apezant%C3%A8" title="Apezantè – Haitian Creole" lang="ht" hreflang="ht" data-title="Apezantè" data-language-autonym="Kreyòl ayisyen" data-language-local-name="Haitian Creole" class="interlanguage-link-target"><span>Kreyòl ayisyen</span></a></li><li class="interlanguage-link interwiki-ltg mw-list-item"><a href="https://ltg.wikipedia.org/wiki/Bezsvors" title="Bezsvors – Latgalian" lang="ltg" hreflang="ltg" data-title="Bezsvors" data-language-autonym="Latgaļu" data-language-local-name="Latgalian" class="interlanguage-link-target"><span>Latgaļu</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Bezsvara_st%C4%81voklis" title="Bezsvara stāvoklis – Latvian" lang="lv" hreflang="lv" data-title="Bezsvara stāvoklis" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Nesvarumas" title="Nesvarumas – Lithuanian" lang="lt" hreflang="lt" data-title="Nesvarumas" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%91%D0%B5%D1%81%D1%82%D0%B5%D0%B6%D0%BD%D0%BE%D1%81%D1%82" title="Бестежност – Macedonian" lang="mk" hreflang="mk" data-title="Бестежност" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Kenirberatan" title="Kenirberatan – Malay" lang="ms" hreflang="ms" data-title="Kenirberatan" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-min mw-list-item"><a href="https://min.wikipedia.org/wiki/Tanpa_beban" title="Tanpa beban – Minangkabau" lang="min" hreflang="min" data-title="Tanpa beban" data-language-autonym="Minangkabau" data-language-local-name="Minangkabau" class="interlanguage-link-target"><span>Minangkabau</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Gewichtloosheid" title="Gewichtloosheid – Dutch" lang="nl" hreflang="nl" data-title="Gewichtloosheid" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E7%84%A1%E9%87%8D%E9%87%8F%E7%8A%B6%E6%85%8B" title="無重量状態 – Japanese" lang="ja" hreflang="ja" data-title="無重量状態" data-language-autonym="日本語" data-language-local-name="Japanese" 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<div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Zero apparent weight, microgravity</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">"Zero gravity" and "Zero-G" redirect here. For other uses, see <a href="/wiki/Zero_gravity_(disambiguation)" class="mw-redirect mw-disambig" title="Zero gravity (disambiguation)">Zero gravity (disambiguation)</a>.</div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Foale_ZeroG.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Foale_ZeroG.jpg/300px-Foale_ZeroG.jpg" decoding="async" width="300" height="199" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Foale_ZeroG.jpg/450px-Foale_ZeroG.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Foale_ZeroG.jpg/600px-Foale_ZeroG.jpg 2x" data-file-width="3032" data-file-height="2008" /></a><figcaption>Astronauts on the <a href="/wiki/International_Space_Station" title="International Space Station">International Space Station</a> experience only microgravity and thus display an example of weightlessness. <a href="/wiki/Michael_Foale" title="Michael Foale">Michael Foale</a> can be seen exercising in the foreground.</figcaption></figure> <p><b>Weightlessness</b> is the complete or near-complete absence of the sensation of <a href="/wiki/Weight" title="Weight">weight</a>, i.e., zero <a href="/wiki/Apparent_weight" title="Apparent weight">apparent weight</a>. It is also termed <b>zero g-force</b>, or <b>zero-g</b> (named after the <a href="/wiki/G-force" title="G-force">g-force</a>)<sup id="cite_ref-space.com_1-0" class="reference"><a href="#cite_note-space.com-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> or, incorrectly, <b>zero gravity</b>. </p><p><b>Microgravity environment</b> is more or less synonymous in its effects, with the recognition that g-forces are never exactly zero. </p><p>Weight is a measurement of the force on an object at rest in a relatively strong gravitational field (such as on the surface of the Earth). These weight-sensations originate from contact with supporting floors, seats, beds, scales, and the like. A sensation of weight is also produced, even when the gravitational field is zero, when contact forces act upon and overcome a body's <a href="/wiki/Inertia" title="Inertia">inertia</a> by mechanical, non-<a href="/wiki/Gravity" title="Gravity">gravitational</a> forces- such as in a <a href="/wiki/Centrifuge" title="Centrifuge">centrifuge</a>, a rotating <a href="/wiki/Space_station" title="Space station">space station</a>, or within an accelerating vehicle. </p><p>When the <a href="/wiki/Gravitational_field" title="Gravitational field">gravitational field</a> is non-uniform, a body in <a href="/wiki/Free_fall" title="Free fall">free fall</a> experiences <a href="/wiki/Tidal_force" title="Tidal force">tidal forces</a> and is not stress-free. Near a <a href="/wiki/Black_hole" title="Black hole">black hole</a>, such tidal effects can be very strong, leading to <i><a href="/wiki/Spaghettification" title="Spaghettification">spaghettification</a></i>. In the case of the Earth, the effects are minor, especially on objects of relatively small dimensions (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity, and it prevails in orbiting spacecraft. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Weightlessness_in_Newtonian_mechanics">Weightlessness in Newtonian mechanics</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=1" title="Edit section: Weightlessness in Newtonian mechanics"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Spring_in_and_out_of_stress.PNG" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Spring_in_and_out_of_stress.PNG/220px-Spring_in_and_out_of_stress.PNG" decoding="async" width="220" height="189" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Spring_in_and_out_of_stress.PNG/330px-Spring_in_and_out_of_stress.PNG 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b2/Spring_in_and_out_of_stress.PNG/440px-Spring_in_and_out_of_stress.PNG 2x" data-file-width="518" data-file-height="445" /></a><figcaption>In the left half, the spring is far away from any gravity source. In the right half, it is in a uniform gravitation field. <b>a</b>) Zero gravity and weightless <b>b</b>) Zero gravity but not weightless (Spring is rocket propelled) <b>c</b>) Spring is in free fall and weightless <b>d</b>) Spring rests on a plinth and has both weight<sub>1</sub> and weight<sub>2</sub>.</figcaption></figure> <p>In Newtonian physics, the sensation of weightlessness experienced by astronauts is not the result of there being zero gravitational acceleration (as seen from the Earth), but of there being no <a href="/wiki/G-force" title="G-force">g-force</a> that an astronaut can feel because of the free-fall condition, and also there being zero difference between the acceleration of the spacecraft and the acceleration of the astronaut. Space journalist <a href="/wiki/James_Oberg" title="James Oberg">James Oberg</a> explains the phenomenon this way:<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p> <style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote"><p>The myth that satellites remain in orbit because they have "escaped Earth's gravity" is perpetuated further (and falsely) by almost universal misuse of the word "zero gravity" to describe the free-falling conditions aboard orbiting space vehicles. Of course, this isn't true; gravity still exists in space. It keeps satellites from flying straight off into interstellar emptiness. What's missing is "weight", the resistance of gravitational attraction by an anchored structure or a counterforce. Satellites stay in space because of their tremendous horizontal speed, which allows them—while being unavoidably pulled toward Earth by gravity—to fall "over the horizon." The ground's curved withdrawal along the Earth's round surface offsets the satellites' fall toward the ground. Speed, not position or lack of gravity, keeps satellites in orbit around the Earth.</p></blockquote> <p>From the perspective of an observer not moving with the object (i.e. in an <a href="/wiki/Inertial_reference_frame" class="mw-redirect" title="Inertial reference frame">inertial reference frame</a>) the force of gravity on an object in free fall is exactly the same as usual.<sup id="cite_ref-Chandler_3-0" class="reference"><a href="#cite_note-Chandler-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> A classic example is an elevator car where the cable has been cut and it plummets toward Earth, accelerating at a rate equal to the 9.81 meters per second per second. In this scenario, the gravitational force is mostly, but not entirely, diminished; anyone in the elevator would experience an absence of the usual gravitational pull, however the force is not <i>exactly</i> zero. Since gravity is a force directed towards the center of the Earth, two balls a horizontal distance apart would be pulled in slightly different directions and would come closer together as the elevator dropped. Also, if they were some vertical distance apart the lower one would experience a higher gravitational force than the upper one since gravity diminishes according to the <a href="/wiki/Inverse_square_law" class="mw-redirect" title="Inverse square law">inverse square law</a>. These two second-order effects are examples of micro gravity.<sup id="cite_ref-Chandler_3-1" class="reference"><a href="#cite_note-Chandler-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Weightless_and_reduced_weight_environments">Weightless and reduced weight environments</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=2" title="Edit section: Weightless and reduced weight environments"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Zero_gravity_flight_trajectory_C9-565_vector.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Zero_gravity_flight_trajectory_C9-565_vector.svg/250px-Zero_gravity_flight_trajectory_C9-565_vector.svg.png" decoding="async" width="220" height="157" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Zero_gravity_flight_trajectory_C9-565_vector.svg/330px-Zero_gravity_flight_trajectory_C9-565_vector.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Zero_gravity_flight_trajectory_C9-565_vector.svg/440px-Zero_gravity_flight_trajectory_C9-565_vector.svg.png 2x" data-file-width="300" data-file-height="214" /></a><figcaption>Zero gravity flight maneuver</figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="Reduced_weight_in_aircraft">Reduced weight in aircraft</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=3" title="Edit section: Reduced weight in aircraft"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Reduced-gravity_aircraft" title="Reduced-gravity aircraft">Reduced-gravity aircraft</a></div> <p>Airplanes have been used since 1959 to provide a nearly weightless environment in which to train astronauts, conduct research, and film motion pictures. Such aircraft are commonly referred by the nickname "<a href="/wiki/Reduced-gravity_aircraft" title="Reduced-gravity aircraft">Vomit Comet</a>". </p><p>To create a weightless environment, the airplane flies in a 10 km (6 mi) <a href="/wiki/Parabola" title="Parabola">parabolic</a> arc, first climbing, then entering a powered dive. During the arc, the propulsion and steering of the aircraft are controlled to cancel the <a href="/wiki/Drag_(physics)" title="Drag (physics)">drag</a> (air resistance) on the plane out, leaving the plane to behave as if it were free-falling in a vacuum. </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:KC-135A_plane_ascending_for_zero_gravity_maneuver.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/ed/KC-135A_plane_ascending_for_zero_gravity_maneuver.jpg/220px-KC-135A_plane_ascending_for_zero_gravity_maneuver.jpg" decoding="async" width="220" height="166" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/e/ed/KC-135A_plane_ascending_for_zero_gravity_maneuver.jpg 1.5x" data-file-width="260" data-file-height="196" /></a><figcaption>NASA's KC-135A plane ascending for a zero gravity maneuver</figcaption></figure> <div class="mw-heading mw-heading4"><h4 id="NASA's_Reduced_Gravity_Aircraft"><span id="NASA.27s_Reduced_Gravity_Aircraft"></span>NASA's Reduced Gravity Aircraft</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=4" title="Edit section: NASA's Reduced Gravity Aircraft"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Versions of such airplanes have been operated by <a href="/wiki/NASA" title="NASA">NASA</a>'s Reduced Gravity Research Program since 1973, where the unofficial nickname originated.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> NASA later adopted the official nickname 'Weightless Wonder' for publication.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> NASA's current Reduced Gravity Aircraft, "Weightless Wonder VI", a <a href="/wiki/McDonnell_Douglas_C-9" title="McDonnell Douglas C-9">McDonnell Douglas C-9</a>, is based at <a href="/wiki/Ellington_Field" class="mw-redirect" title="Ellington Field">Ellington Field</a> (KEFD), near <a href="/wiki/Lyndon_B._Johnson_Space_Center" class="mw-redirect" title="Lyndon B. Johnson Space Center">Lyndon B. Johnson Space Center</a>. </p><p>NASA's <a href="/wiki/Microgravity_University" title="Microgravity University">Microgravity University</a> - Reduced Gravity Flight Opportunities Plan, also known as the Reduced Gravity Student Flight Opportunities Program, allows teams of undergraduates to submit a microgravity experiment proposal. If selected, the teams design and implement their experiment, and students are invited to fly on NASA's Vomit Comet.<sup class="noprint Inline-Template Template-Fact" style="white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed"><span title="This claim needs references to reliable sources. (November 2022)">citation needed</span></a></i>]</sup> </p> <div class="mw-heading mw-heading4"><h4 id="European_Space_Agency_A310_Zero-G">European Space Agency A310 Zero-G</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=5" title="Edit section: European Space Agency A310 Zero-G"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <a href="/wiki/European_Space_Agency" title="European Space Agency">European Space Agency</a> (ESA) flies parabolic flights on a specially modified <a href="/wiki/Airbus_A310" title="Airbus A310">Airbus A310-300</a> aircraft<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> to perform research in microgravity. Along with the French <a href="/wiki/CNES" title="CNES">CNES</a> and the German <a href="/wiki/German_Aerospace_Center" title="German Aerospace Center">DLR</a>, they conduct <i>campaigns</i> of three flights over consecutive days, with each flight's about 30 parabolae totalling about 10 minutes of weightlessness. These campaigns are currently operated from <a href="/wiki/Bordeaux_-_M%C3%A9rignac_Airport" class="mw-redirect" title="Bordeaux - Mérignac Airport">Bordeaux - Mérignac Airport</a> by <a rel="nofollow" class="external text" href="https://www.challenges.fr/entreprise/comment-des-compagnies-blacklistees-continuent-a-desservir-l-europe_324589">Novespace</a>,<sup id="cite_ref-novespace_7-0" class="reference"><a href="#cite_note-novespace-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> a subsidiary of <a href="/wiki/CNES" title="CNES">CNES</a>; the aircraft is flown by test pilots from <a href="https://fr.wikipedia.org/wiki/DGA_Essais_en_vol" class="extiw" title="fr:DGA Essais en vol">DGA Essais en Vol</a>. </p><p>As of May 2010<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Weightlessness&action=edit">[update]</a></sup>, the ESA has flown 52 scientific campaigns and also 9 student parabolic flight campaigns.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> Their first Zero-G flights were in 1984 using a NASA KC-135 aircraft in <a href="/wiki/Houston" title="Houston">Houston</a>, Texas. Other aircraft used include the <a href="/wiki/Russia" title="Russia">Russian</a> <a href="/wiki/Ilyushin_Il-76" title="Ilyushin Il-76">Ilyushin Il-76</a> MDK before founding Novespace, then a French <a href="/wiki/Sud_Aviation_Caravelle" title="Sud Aviation Caravelle">Caravelle</a> and an <a href="https://fr.wikipedia.org/wiki/Airbus_A300_ZERO-G" class="extiw" title="fr:Airbus A300 ZERO-G">Airbus A300 Zero-G</a>.<sup id="cite_ref-esa.int_main_page_9-0" class="reference"><a href="#cite_note-esa.int_main_page-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-esa.int_next_campaign_10-0" class="reference"><a href="#cite_note-esa.int_next_campaign-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-esa.int_Campaign_Organisation_11-0" class="reference"><a href="#cite_note-esa.int_Campaign_Organisation-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="Commercial_flights_for_public_passengers">Commercial flights for public passengers</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=6" title="Edit section: Commercial flights for public passengers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:PeterZG-small.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/PeterZG-small.jpg/220px-PeterZG-small.jpg" decoding="async" width="220" height="330" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fd/PeterZG-small.jpg/330px-PeterZG-small.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fd/PeterZG-small.jpg/440px-PeterZG-small.jpg 2x" data-file-width="599" data-file-height="898" /></a><figcaption>Inside a Russian Ilyushin 76MDK of the Gagarin Cosmonaut Training Center</figcaption></figure> <p>Novespace created Air Zero G in 2012 to share the experience of weightlessness with 40 public passengers per flight, using the same A310 ZERO-G as for scientific experiences.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> These flights are sold by <a href="/w/index.php?title=Avico&action=edit&redlink=1" class="new" title="Avico (page does not exist)">Avico</a>, are mainly operated from <a href="/wiki/Bordeaux%E2%80%93M%C3%A9rignac_Airport" title="Bordeaux–Mérignac Airport">Bordeaux-Merignac</a>, <a href="/wiki/France" title="France">France</a>, and intend to promote European space research, allowing public passengers to feel weightlessness. <a href="/wiki/Jean-Fran%C3%A7ois_Clervoy" title="Jean-François Clervoy">Jean-François Clervoy</a>, Chairman of Novespace and <a href="/wiki/ESA" class="mw-redirect" title="ESA">ESA</a> astronaut, flies with these one-day astronauts on board A310 Zero-G. After the flight, he explains the quest of space and talks about the 3 space travels he did along his career. The aircraft has also been used for cinema purposes, with <a href="/wiki/Tom_Cruise" title="Tom Cruise">Tom Cruise</a> and <a href="/wiki/Annabelle_Wallis" title="Annabelle Wallis">Annabelle Wallis</a> for <a href="/wiki/The_Mummy_(2017_film)" title="The Mummy (2017 film)">the Mummy</a> in 2017.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>The <a href="/wiki/Zero_Gravity_Corporation" title="Zero Gravity Corporation">Zero Gravity Corporation</a> operates a modified <a href="/wiki/Boeing_727" title="Boeing 727">Boeing 727</a> which flies parabolic arcs to create 25–30 seconds of weightlessness. </p> <div class="mw-heading mw-heading3"><h3 id="Ground-based_drop_facilities">Ground-based drop facilities</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=7" title="Edit section: Ground-based drop facilities"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-right" typeof="mw:File/Thumb"><a href="/wiki/File:Zero_G_-_GPN-2000-001456.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Zero_G_-_GPN-2000-001456.jpg/220px-Zero_G_-_GPN-2000-001456.jpg" decoding="async" width="220" height="275" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Zero_G_-_GPN-2000-001456.jpg/330px-Zero_G_-_GPN-2000-001456.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/ee/Zero_G_-_GPN-2000-001456.jpg/440px-Zero_G_-_GPN-2000-001456.jpg 2x" data-file-width="2400" data-file-height="3000" /></a><figcaption>Zero-gravity testing at the NASA <a href="/wiki/Zero_Gravity_Research_Facility" title="Zero Gravity Research Facility">Zero Gravity Research Facility</a> </figcaption></figure> <p>Ground-based facilities that produce weightless conditions for research purposes are typically referred to as <a href="/wiki/Drop_tube" title="Drop tube">drop tubes</a> or drop towers. </p><p>NASA's <a href="/wiki/Zero_Gravity_Research_Facility" title="Zero Gravity Research Facility">Zero Gravity Research Facility</a>, located at the <a href="/wiki/Glenn_Research_Center" title="Glenn Research Center">Glenn Research Center</a> in <a href="/wiki/Cleveland,_Ohio" class="mw-redirect" title="Cleveland, Ohio">Cleveland, Ohio</a>, is a 145 m vertical shaft, largely below the ground, with an integral vacuum drop chamber, in which an experiment vehicle can have a free fall for a duration of 5.18 seconds, falling a distance of 132 m. The experiment vehicle is stopped in approximately 4.5 m of <a href="/wiki/Pelletizing" title="Pelletizing">pellets</a> of expanded <a href="/wiki/Polystyrene" title="Polystyrene">polystyrene</a>, experiencing a peak <a href="/wiki/Deceleration" class="mw-redirect" title="Deceleration">deceleration</a> rate of 65 <i>g</i>. </p><p>Also at NASA Glenn is the 2.2 Second Drop Tower, which has a drop distance of 24.1 m. Experiments are dropped in a drag shield in order to reduce the effects of air drag. The entire package is stopped in a 3.3 m tall air bag, at a peak deceleration rate of approximately 20 <i>g</i>. While the Zero Gravity Facility conducts one or two drops per day, the 2.2 Second Drop Tower can conduct up to twelve drops per day. </p><p>NASA's <a href="/wiki/Marshall_Space_Flight_Center" title="Marshall Space Flight Center">Marshall Space Flight Center</a> hosts another drop tube facility that is 105 m tall and provides a 4.6 s free fall under near-<a href="/wiki/Vacuum" title="Vacuum">vacuum</a> conditions.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> </p><p>Other drop facilities worldwide include: </p> <ul><li><a href="/w/index.php?title=Micro-Gravity_Laboratory_of_Japan&action=edit&redlink=1" class="new" title="Micro-Gravity Laboratory of Japan (page does not exist)">Micro-Gravity Laboratory of Japan</a> (MGLAB) – 4.5 s free fall</li> <li>Experimental drop tube of the metallurgy department of <a href="/wiki/Grenoble" title="Grenoble">Grenoble</a> – 3.1 s free fall</li> <li><a href="/wiki/Fallturm_Bremen" title="Fallturm Bremen">Fallturm Bremen</a> <a href="/wiki/University_of_Bremen" title="University of Bremen">University of Bremen</a> in <a href="/wiki/Bremen_(city)" class="mw-redirect" title="Bremen (city)">Bremen</a> – 4.74 s free fall</li> <li>Queensland University of Technology Drop Tower – 2.0 s free fall</li> <li>National Centre for Combustion Research and Development at <a href="/wiki/IIT_Madras" title="IIT Madras">IIT-M</a> – 2.5 s free fall <sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading3"><h3 id="Random_Positioning_Machines">Random Positioning Machines</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=8" title="Edit section: Random Positioning Machines"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Another ground-based approach to simulate weightlessness for biological samples is a "3D-clinostat," also called a <a href="/wiki/Random_positioning_machine" title="Random positioning machine">random positioning machine</a>. Unlike a regular <a href="/wiki/Clinostat" title="Clinostat">clinostat</a>, the random positioning machine rotates in two axes simultaneously and progressively establishes a microgravity-like condition via the principle of gravity-vector-averaging. </p> <div class="mw-heading mw-heading3"><h3 id="Neutral_buoyancy">Neutral buoyancy</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=9" title="Edit section: Neutral buoyancy"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1251242444">.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}</style><table class="box-Empty_section plainlinks metadata ambox mbox-small-left ambox-content" role="presentation"><tbody><tr><td class="mbox-image"><span typeof="mw:File"><a href="/wiki/File:Wiki_letter_w_cropped.svg" class="mw-file-description"><img alt="[icon]" src="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/20px-Wiki_letter_w_cropped.svg.png" decoding="async" width="20" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/30px-Wiki_letter_w_cropped.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Wiki_letter_w_cropped.svg/40px-Wiki_letter_w_cropped.svg.png 2x" data-file-width="44" data-file-height="31" /></a></span></td><td class="mbox-text"><div class="mbox-text-span"><b>This section is empty.</b> You can help by <a class="external text" href="https://en.wikipedia.org/w/index.php?title=Weightlessness&action=edit&section=">adding to it</a>. <span class="date-container"><i>(<span class="date">November 2022</span>)</i></span></div></td></tr></tbody></table> <div class="mw-heading mw-heading3"><h3 id="Orbits">Orbits</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=10" title="Edit section: Orbits"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Centripetal_force_diagram.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Centripetal_force_diagram.svg/220px-Centripetal_force_diagram.svg.png" decoding="async" width="220" height="185" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Centripetal_force_diagram.svg/330px-Centripetal_force_diagram.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Centripetal_force_diagram.svg/440px-Centripetal_force_diagram.svg.png 2x" data-file-width="596" data-file-height="500" /></a><figcaption>The relationship between acceleration and velocity vectors in an orbiting spacecraft</figcaption></figure> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Weightless_hair.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Weightless_hair.jpg/250px-Weightless_hair.jpg" decoding="async" width="220" height="334" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/79/Weightless_hair.jpg/330px-Weightless_hair.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/7/79/Weightless_hair.jpg 2x" data-file-width="422" data-file-height="640" /></a><figcaption>US astronaut <a href="/wiki/Marsha_Ivins" title="Marsha Ivins">Marsha Ivins</a> demonstrates the effect of weightlessness on long hair during <a href="/wiki/STS-98" title="STS-98">STS-98</a></figcaption></figure> <figure typeof="mw:File/Thumb"><a href="/wiki/File:STS-130_Endeavour_flyaround_5.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5b/STS-130_Endeavour_flyaround_5.jpg/300px-STS-130_Endeavour_flyaround_5.jpg" decoding="async" width="300" height="199" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5b/STS-130_Endeavour_flyaround_5.jpg/450px-STS-130_Endeavour_flyaround_5.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5b/STS-130_Endeavour_flyaround_5.jpg/600px-STS-130_Endeavour_flyaround_5.jpg 2x" data-file-width="3072" data-file-height="2040" /></a><figcaption>The <a href="/wiki/International_Space_Station" title="International Space Station">International Space Station</a> in <a href="/wiki/Orbit" title="Orbit">orbit</a> around <a href="/wiki/Earth" title="Earth">Earth</a>, February 2010. The ISS is in a <b>micro-g environment</b>.</figcaption></figure> <p>On the International Space Station (ISS), there are small g-forces come from tidal effects, gravity from objects other than the Earth, such as astronauts, the spacecraft, and the <a href="/wiki/Sun" title="Sun">Sun</a>, <a href="/wiki/Air_resistance" class="mw-redirect" title="Air resistance">air resistance</a>, and astronaut movements that impart <a href="/wiki/Momentum" title="Momentum">momentum</a> to the space station).<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> The symbol for microgravity, <i>μg</i>, was used on the insignias of <a href="/wiki/Space_Shuttle" title="Space Shuttle">Space Shuttle</a> flights <a href="/wiki/STS-87" title="STS-87">STS-87</a> and <a href="/wiki/STS-107" title="STS-107">STS-107</a>, because these flights were devoted to microgravity research in <a href="/wiki/Low_Earth_orbit" title="Low Earth orbit">low Earth orbit</a>. </p> <div class="mw-heading mw-heading4"><h4 id="Sub-Orbital_flights">Sub-Orbital flights</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=11" title="Edit section: Sub-Orbital flights"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Over the years, biomedical research on the implications of space flight has become more prominent in evaluating possible pathophysiological changes in humans.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Sub-orbital_spaceflight" title="Sub-orbital spaceflight">Sub-orbital flights</a> seize the approximated weightlessness, or μg, in the low Earth orbit and represent a promising research model for short-term exposure. Examples of such approaches are the <a href="/wiki/Maser_(rocket)" title="Maser (rocket)">MASER</a>, <a href="/wiki/Maxus_(rocket)" title="Maxus (rocket)">MAXUS</a>, or <a href="/wiki/TEXUS" title="TEXUS">TEXUS</a> program run by the <a href="/wiki/Swedish_Space_Corporation" title="Swedish Space Corporation">Swedish Space Corporation</a> and the <a href="/wiki/ESA" class="mw-redirect" title="ESA">European Space Agency</a>. </p> <div class="mw-heading mw-heading4"><h4 id="Orbital_Motion">Orbital Motion</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=12" title="Edit section: Orbital Motion"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Orbital_motion" class="mw-redirect" title="Orbital motion">Orbital motion</a> is a form of free fall.<sup id="cite_ref-Chandler_3-2" class="reference"><a href="#cite_note-Chandler-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> Objects in orbit are not perfectly weightless due to several effects: </p> <ul><li>Effects depending on relative position in the spacecraft: <ul><li>Because the force of gravity decreases with distance, objects with non-zero size will be subjected to a <a href="/wiki/Tidal_force" title="Tidal force">tidal force</a>, or a differential pull, between the ends of the object nearest and furthest from the Earth. (An extreme version of this effect is <a href="/wiki/Spaghettification" title="Spaghettification">spaghettification</a>.) In a spacecraft in low Earth orbit (LEO), the <a href="/wiki/Centrifugal_force" title="Centrifugal force">centrifugal force</a> is also greater on the side of the spacecraft furthest from the Earth. At a 400 km LEO altitude, the overall differential in g-force is approximately 0.384 μ<i>g</i>/m.<sup id="cite_ref-conceptual_20-0" class="reference"><a href="#cite_note-conceptual-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Chandler_3-3" class="reference"><a href="#cite_note-Chandler-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup></li> <li>Gravity between the spacecraft and an object within it may make the object slowly "fall" toward a more massive part of it. The acceleration is 0.007 μ<i>g</i> for 1000 kg at 1 m distance.</li></ul></li> <li>Uniform effects (which could be compensated): <ul><li>Though extremely thin, there is some air at orbital altitudes of 185 to 1,000 km. This atmosphere causes minuscule deceleration due to friction. This could be compensated by a small continuous thrust, but in practice the deceleration is only compensated from time to time, so the tiny g-force of this effect is not eliminated.</li> <li>The effects of the <a href="/wiki/Solar_wind" title="Solar wind">solar wind</a> and <a href="/wiki/Radiation_pressure" title="Radiation pressure">radiation pressure</a> are similar, but directed away from the Sun. Unlike the effect of the atmosphere, it does not reduce with altitude.</li></ul></li> <li>Other Effects: <ul><li>Routine crew activity: Due to the <a href="/wiki/Momentum#Conservation" title="Momentum">conservation of momentum</a>, any crew member aboard a spacecraft pushing off a wall causes the spacecraft to move in the opposite direction.</li> <li>Structural Vibration: Stress enacted on the hull of the spacecraft results in the spacecraft bending, causing apparent acceleration.</li></ul></li></ul> <div class="mw-heading mw-heading3"><h3 id="Weightlessness_at_the_center_of_a_planet">Weightlessness at the center of a planet</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=13" title="Edit section: Weightlessness at the center of a planet"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>If an object were to travel to the center of a spherical planet unimpeded by the planet's materials, it would achieve a state of weightlessness upon arriving at the center of the planet's <a href="/wiki/Planetary_core" title="Planetary core">core</a>. This is because the mass of the surrounding planet is exerting an equal gravitational pull in all directions from the center, canceling out the pull of any one direction, establishing a space with no gravitational pull.<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Absence_of_gravity">Absence of gravity</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=14" title="Edit section: Absence of gravity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A "stationary" micro-g environment<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> would require travelling far enough into deep space so as to reduce the effect of gravity by <a href="/wiki/Attenuation" title="Attenuation">attenuation</a> to almost zero. This is simple in conception but requires travelling a very large distance, rendering it highly impractical. For example, to reduce the gravity of the Earth by a factor of one million, one needs to be at a distance of 6 million kilometres from the Earth, but to reduce the gravity of the Sun to this amount, one has to be at a distance of 3.7 billion kilometres. This is not impossible, but it has only been achieved thus far by four <a href="/wiki/Interstellar_probe" title="Interstellar probe">interstellar probes</a>: (<a href="/wiki/Voyager_1" title="Voyager 1">Voyager 1</a> and <a href="/wiki/Voyager_2" title="Voyager 2">2</a> of the <a href="/wiki/Voyager_program" title="Voyager program">Voyager program</a>, and <a href="/wiki/Pioneer_10" title="Pioneer 10">Pioneer 10</a> and <a href="/wiki/Pioneer_11" title="Pioneer 11">11</a> of the <a href="/wiki/Pioneer_program" title="Pioneer program">Pioneer program</a>.) At the <a href="/wiki/Speed_of_light" title="Speed of light">speed of light</a> it would take roughly three and a half hours to reach this micro-gravity environment (a region of space where the acceleration due to gravity is one-millionth of that experienced on the Earth's surface). To reduce the gravity to one-thousandth of that on Earth's surface, however, one needs only to be at a distance of 200,000 km. </p> <table class="wikitable"> <tbody><tr> <th rowspan="2">Location</th> <th colspan="3">Gravity due to</th> <th rowspan="2">Total </th></tr> <tr> <th><a href="/wiki/Earth" title="Earth">Earth</a></th> <th><a href="/wiki/Sun" title="Sun">Sun</a></th> <th>rest of <a href="/wiki/Milky_Way" title="Milky Way">Milky Way</a> </th></tr> <tr> <td>Earth's surface</td> <td>9.81 m/s<sup>2</sup></td> <td>6 mm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup> = 6 mm/s/yr</td> <td>9.81 m/s<sup>2</sup> </td></tr> <tr> <td><a href="/wiki/Low_Earth_orbit" title="Low Earth orbit">Low Earth orbit</a></td> <td>9 m/s<sup>2</sup></td> <td>6 mm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>9 m/s<sup>2</sup> </td></tr> <tr> <td>200,000 km from Earth</td> <td>10 mm/s<sup>2</sup></td> <td>6 mm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>up to 12 mm/s<sup>2</sup> </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="7009600000000000000♠"></span>6<span style="margin-left:0.25em;margin-right:0.15em;">×</span>10<sup>6</sup> km</span> from Earth</td> <td>10 μm/s<sup>2</sup></td> <td>6 mm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>6 mm/s<sup>2</sup> </td></tr> <tr> <td><span class="nowrap"><span data-sort-value="7012370000000000000♠"></span>3.7<span style="margin-left:0.25em;margin-right:0.15em;">×</span>10<sup>9</sup> km</span> from Earth</td> <td>29 pm/s<sup>2</sup></td> <td>10 μm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>10 μm/s<sup>2</sup> </td></tr> <tr> <td><a href="/wiki/Voyager_1" title="Voyager 1">Voyager 1</a> (<span class="nowrap"><span data-sort-value="7013170000000000000♠"></span>17<span style="margin-left:0.25em;margin-right:0.15em;">×</span>10<sup>9</sup> km</span> from Earth)</td> <td>1 pm/s<sup>2</sup></td> <td>500 nm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>500 nm/s<sup>2</sup> </td></tr> <tr> <td>0.1 <a href="/wiki/Light-year" title="Light-year">light-year</a> from Earth</td> <td>400 am/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>200 pm/s<sup>2</sup></td> <td>up to 400 pm/s<sup>2</sup> </td></tr></tbody></table> <p>At a distance relatively close to Earth (less than 3000 km), gravity is only slightly reduced. As an object orbits a body such as the Earth, gravity is still attracting objects towards the Earth and the object is accelerated downward at almost 1g. Because the objects are typically moving laterally with respect to the surface at such immense speeds, the object will not lose altitude because of the curvature of the Earth. When viewed from an orbiting observer, other close objects in space appear to be floating because everything is being pulled towards Earth at the same speed, but also moving forward as the Earth's surface "falls" away below. All these objects are in <a href="/wiki/Free_fall" title="Free fall">free fall</a>, not zero gravity. </p><p>Compare the <a href="/wiki/Gravitational_potential#Numerical_values" title="Gravitational potential">gravitational potential at some of these locations</a>. </p> <div class="mw-heading mw-heading2"><h2 id="Health_effects">Health effects</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=15" title="Edit section: Health effects"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Effect_of_spaceflight_on_the_human_body" title="Effect of spaceflight on the human body">Effect of spaceflight on the human body</a> and <a href="/wiki/Space_medicine" title="Space medicine">Space medicine</a></div> <figure class="mw-default-size mw-halign-left" typeof="mw:File/Thumb"><a href="/wiki/File:Clayton_Anderson_zero_g.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Clayton_Anderson_zero_g.jpg/220px-Clayton_Anderson_zero_g.jpg" decoding="async" width="220" height="130" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Clayton_Anderson_zero_g.jpg/330px-Clayton_Anderson_zero_g.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b8/Clayton_Anderson_zero_g.jpg/440px-Clayton_Anderson_zero_g.jpg 2x" data-file-width="1322" data-file-height="780" /></a><figcaption>Astronaut <a href="/wiki/Clayton_Anderson" title="Clayton Anderson">Clayton Anderson</a> as a large drop of water floats in front of him on the Discovery. <a href="/wiki/Cohesion_(chemistry)" title="Cohesion (chemistry)">Cohesion</a> plays a bigger role in space.</figcaption></figure> <p>Following the advent of space stations that can be inhabited for long periods, exposure to weightlessness has been demonstrated to have some deleterious effects on human health.<sup id="cite_ref-NYT-20140127_23-0" class="reference"><a href="#cite_note-NYT-20140127-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> Humans are well-adapted to the physical conditions at the surface of the Earth. In response to an extended period of weightlessness, various physiological systems begin to change and atrophy. Though these changes are usually temporary, long-term health issues can result. </p><p>The most common problem experienced by humans in the initial hours of weightlessness is known as <a href="/wiki/Space_adaptation_syndrome" title="Space adaptation syndrome">space adaptation syndrome</a> or SAS, commonly referred to as space sickness. Symptoms of SAS include <a href="/wiki/Nausea" title="Nausea">nausea</a> and <a href="/wiki/Vomiting" title="Vomiting">vomiting</a>, <a href="/wiki/Vertigo_(medical)" class="mw-redirect" title="Vertigo (medical)">vertigo</a>, <a href="/wiki/Headache" title="Headache">headaches</a>, <a href="/wiki/Lethargy" title="Lethargy">lethargy</a>, and overall malaise.<sup id="cite_ref-spp22_15_25-0" class="reference"><a href="#cite_note-spp22_15-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> The first case of SAS was reported by <a href="/wiki/Cosmonaut" class="mw-redirect" title="Cosmonaut">cosmonaut</a> <a href="/wiki/Gherman_Titov" title="Gherman Titov">Gherman Titov</a> in 1961. Since then, roughly 45% of all people who have flown in space have suffered from this condition. The duration of space sickness varies, but in no case has it lasted for more than 72 hours, after which the body adjusts to the new environment. NASA jokingly measures SAS using the "Garn scale", named for <a href="/wiki/United_States_Senator" class="mw-redirect" title="United States Senator">United States Senator</a> <a href="/wiki/Jake_Garn" title="Jake Garn">Jake Garn</a>, whose SAS during <a href="/wiki/STS-51-D" title="STS-51-D">STS-51-D</a> was the worst on record. Accordingly, one "Garn" is equivalent to the most severe possible case of SAS.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p><p>The most significant adverse effects of long-term weightlessness are <a href="/wiki/Muscle_atrophy" title="Muscle atrophy">muscle atrophy</a> (see <a href="/wiki/Reduced_muscle_mass,_strength_and_performance_in_space" class="mw-redirect" title="Reduced muscle mass, strength and performance in space">Reduced muscle mass, strength and performance in space</a> for more information) and deterioration of the <a href="/wiki/Skeleton" title="Skeleton">skeleton</a>, or <a href="/wiki/Spaceflight_osteopenia" title="Spaceflight osteopenia">spaceflight osteopenia</a>.<sup id="cite_ref-spp22_15_25-1" class="reference"><a href="#cite_note-spp22_15-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> These effects can be minimized through a regimen of exercise,<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> such as cycling for example. Astronauts subject to long periods of weightlessness wear pants with elastic bands attached between waistband and cuffs to compress the leg bones and reduce osteopenia.<sup id="cite_ref-hl_28-0" class="reference"><a href="#cite_note-hl-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> Other significant effects include fluid redistribution (causing the "moon-face" appearance typical of pictures of astronauts in weightlessness),<sup id="cite_ref-hl_28-1" class="reference"><a href="#cite_note-hl-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> changes in the <a href="/wiki/Cardiovascular_system" class="mw-redirect" title="Cardiovascular system">cardiovascular system</a> as blood pressures and flow velocities change in response to a lack of gravity, a decreased production of <a href="/wiki/Red_blood_cell" title="Red blood cell">red blood cells</a>, balance disorders, and a weakening of the <a href="/wiki/Immune_system" title="Immune system">immune system</a>.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess <a href="/wiki/Flatulence" title="Flatulence">flatulence</a>, and puffiness of the face. These effects begin to reverse quickly upon return to the Earth. </p><p>In addition, after long <a href="/wiki/Space_flight" class="mw-redirect" title="Space flight">space flight</a> missions, astronauts may experience <a href="/wiki/Visual_system" title="Visual system">vision</a> changes.<sup id="cite_ref-Mader-2011_31-0" class="reference"><a href="#cite_note-Mader-2011-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Puiu-20111109_32-0" class="reference"><a href="#cite_note-Puiu-20111109-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-CNN-20120109_33-0" class="reference"><a href="#cite_note-CNN-20120109-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Space-20120313_34-0" class="reference"><a href="#cite_note-Space-20120313-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Radiology-20120313_35-0" class="reference"><a href="#cite_note-Radiology-20120313-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> Such eyesight problems may be a major concern for future deep space flight missions, including a <a href="/wiki/Crewed_mission" class="mw-redirect" title="Crewed mission">crewed mission</a> to the planet <a href="/wiki/Mars" title="Mars">Mars</a>.<sup id="cite_ref-Mader-2011_31-1" class="reference"><a href="#cite_note-Mader-2011-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Puiu-20111109_32-1" class="reference"><a href="#cite_note-Puiu-20111109-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-CNN-20120109_33-1" class="reference"><a href="#cite_note-CNN-20120109-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Space-20120313_34-1" class="reference"><a href="#cite_note-Space-20120313-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-WIRED-20140212_36-0" class="reference"><a href="#cite_note-WIRED-20140212-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> Exposure to high levels of radiation may influence the development of atherosclerosis.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> Clots in the internal jugular vein have recently been detected inflight.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p><p>On December 31, 2012, a <a href="/wiki/NASA" title="NASA">NASA</a>-supported study reported that <a href="/wiki/Human_spaceflight" title="Human spaceflight">human spaceflight</a> may harm the <a href="/wiki/Brain" title="Brain">brains</a> of <a href="/wiki/Astronauts" class="mw-redirect" title="Astronauts">astronauts</a> and accelerate the onset of <a href="/wiki/Alzheimer%27s_disease" title="Alzheimer's disease">Alzheimer's disease</a>.<sup id="cite_ref-PLOS-20121231_39-0" class="reference"><a href="#cite_note-PLOS-20121231-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-SpaceRef-20130101_40-0" class="reference"><a href="#cite_note-SpaceRef-20130101-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NasaWatch-20130103_41-0" class="reference"><a href="#cite_note-NasaWatch-20130103-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> In October 2015, the <a href="/wiki/NASA_Office_of_Inspector_General" title="NASA Office of Inspector General">NASA Office of Inspector General</a> issued a <a href="/wiki/Effect_of_spaceflight_on_the_human_body" title="Effect of spaceflight on the human body">health hazards report</a> related to <a href="/wiki/Human_spaceflight" title="Human spaceflight">human spaceflight</a>, including a <a href="/wiki/Human_mission_to_Mars" title="Human mission to Mars">human mission</a> to <a href="/wiki/Mars" title="Mars">Mars</a>.<sup id="cite_ref-AP-20151029_42-0" class="reference"><a href="#cite_note-AP-20151029-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-NASA-20151029oig_43-0" class="reference"><a href="#cite_note-NASA-20151029oig-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Space_motion_sickness">Space motion sickness</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=16" title="Edit section: Space motion sickness"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Space_adaptation_syndrome" title="Space adaptation syndrome">Space adaptation syndrome</a></div><figure typeof="mw:File/Thumb"><a href="/wiki/File:Astronauts_in_weightlessness.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Astronauts_in_weightlessness.jpg/288px-Astronauts_in_weightlessness.jpg" decoding="async" width="288" height="215" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Astronauts_in_weightlessness.jpg/432px-Astronauts_in_weightlessness.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Astronauts_in_weightlessness.jpg/576px-Astronauts_in_weightlessness.jpg 2x" data-file-width="2807" data-file-height="2091" /></a><figcaption>Six astronauts who had been in training at the Johnson Space Center for almost a year are getting a sample of a micro-g environment</figcaption></figure> <p>Space motion sickness (SMS) is thought to be a subtype of <a href="/wiki/Motion_sickness" title="Motion sickness">motion sickness</a> that plagues nearly half of all astronauts who venture into space.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> SMS, along with facial stuffiness from headward shifts of fluids, headaches, and back pain, is part of a broader complex of symptoms that comprise <i>space adaptation syndrome</i> (SAS).<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> SMS was first described in 1961 during the second orbit of the fourth crewed spaceflight when the cosmonaut <a href="/wiki/Gherman_Titov" title="Gherman Titov">Gherman Titov</a> aboard the <a href="/wiki/Vostok_2" title="Vostok 2">Vostok 2</a>, described feeling disoriented with physical complaints mostly consistent with motion sickness. It is one of the most studied physiological problems of spaceflight but continues to pose a significant difficulty for many astronauts. In some instances, it can be so debilitating that astronauts must sit out from their scheduled occupational duties in space – including missing out on a spacewalk they have spent months training to perform.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> In most cases, however, astronauts will work through the symptoms even with degradation in their performance.<sup id="cite_ref-:03_47-0" class="reference"><a href="#cite_note-:03-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> </p><p>Despite their experiences in some of the most rigorous and demanding physical maneuvers on earth, even the most seasoned astronauts may be affected by SMS, resulting in symptoms of severe <a href="/wiki/Nausea" title="Nausea">nausea</a>, projectile <a href="/wiki/Vomiting" title="Vomiting">vomiting</a>, <a href="/wiki/Fatigue_(medical)" class="mw-redirect" title="Fatigue (medical)">fatigue</a>, malaise (feeling sick), and <a href="/wiki/Headache" title="Headache">headache</a>.<sup id="cite_ref-:03_47-1" class="reference"><a href="#cite_note-:03-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> These symptoms may occur so abruptly and without any warning that space travelers may vomit suddenly without time to contain the emesis, resulting in strong odors and liquid within the cabin which may affect other astronauts.<sup id="cite_ref-:03_47-2" class="reference"><a href="#cite_note-:03-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> Some changes to eye movement behaviors might also occur as a result of SMS.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> Symptoms typically last anywhere from one to three days upon entering weightlessness, but may recur upon reentry to Earth's gravity or even shortly after landing. SMS differs from terrestrial motion sickness in that sweating and pallor are typically minimal or absent and gastrointestinal findings usually demonstrate absent bowel sounds indicating reduced <a href="/wiki/Gastrointestinal_motility" class="mw-redirect" title="Gastrointestinal motility">gastrointestinal motility</a>.<sup id="cite_ref-:13_49-0" class="reference"><a href="#cite_note-:13-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> </p><p>Even when the nausea and vomiting resolve, some central nervous system symptoms may persist which may degrade the astronaut's performance.<sup id="cite_ref-:13_49-1" class="reference"><a href="#cite_note-:13-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> Graybiel and Knepton proposed the term "<a href="/wiki/Sopite_syndrome" title="Sopite syndrome">sopite syndrome</a>" to describe symptoms of lethargy and drowsiness associated with motion sickness in 1976.<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> Since then, their definition has been revised to include "...a symptom complex that develops as a result of exposure to real or apparent motion and is characterized by excessive drowsiness, lassitude, lethargy, mild depression, and reduced ability to focus on an assigned task."<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> Together, these symptoms may pose a substantial threat (albeit temporary) to the astronaut who must remain attentive to life and death issues at all times. </p><p>SMS is most commonly thought to be a disorder of the <a href="/wiki/Vestibular_system" title="Vestibular system">vestibular system</a> that occurs when sensory information from the visual system (sight) and the <a href="/wiki/Proprioception" title="Proprioception">proprioceptive</a> system (posture, position of the body) conflicts with misperceived information from the semicircular canals and the otoliths within the inner ear. This is known as the 'neural mismatch theory' and was first suggested in 1975 by Reason and Brand.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> Alternatively, the fluid shift hypothesis suggests that weightlessness reduces the hydrostatic pressure on the lower body causing fluids to shift toward the head from the rest of the body. These fluid shifts are thought to increase cerebrospinal fluid pressure (causing back aches), intracranial pressure (causing headaches), and inner ear fluid pressure (causing vestibular dysfunction).<sup id="cite_ref-Heer_77–79_53-0" class="reference"><a href="#cite_note-Heer_77–79-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> </p><p>Despite a multitude of studies searching for a solution to the problem of SMS, it remains an ongoing problem for space travel. Most non-pharmacological countermeasures such as training and other physical maneuvers have offered minimal benefit. Thornton and Bonato noted, "Pre- and inflight adaptive efforts, some of them mandatory and most of them onerous, have been, for the most part, operational failures."<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> To date, the most common intervention is <a href="/wiki/Promethazine" title="Promethazine">promethazine</a>, an injectable <a href="/wiki/Antihistamine" title="Antihistamine">antihistamine</a> with <a href="/wiki/Antiemetic" title="Antiemetic">antiemetic</a> properties, but sedation can be a problematic side effect.<sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> Other common pharmacological options include <a href="/wiki/Metoclopramide" title="Metoclopramide">metoclopramide</a>, as well as oral and transdermal application of <a href="/wiki/Scopolamine" title="Scopolamine">scopolamine</a>, but drowsiness and sedation are common side effects for these medications as well.<sup id="cite_ref-Heer_77–79_53-1" class="reference"><a href="#cite_note-Heer_77–79-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Musculoskeletal_effects">Musculoskeletal effects</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=17" title="Edit section: Musculoskeletal effects"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>In the space (or microgravity) environment the effects of unloading varies significantly among individuals, with sex differences compounding the variability.<sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> Differences in mission duration, and the small sample size of astronauts participating in the same mission also adds to the variability to the <a href="/wiki/Musculoskeletal_disorder" title="Musculoskeletal disorder">musculoskeletal disorders</a> that are seen in space.<sup id="cite_ref-:23_57-0" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> In addition to muscle loss, microgravity leads to increased <a href="/wiki/Bone_resorption" title="Bone resorption">bone resorption</a>, decreased <a href="/wiki/Bone_mineral_density" class="mw-redirect" title="Bone mineral density">bone mineral density</a>, and increased fracture risks. Bone resorption leads to increased urinary levels of <a href="/wiki/Calcium_in_biology" title="Calcium in biology">calcium</a>, which can subsequently lead to an increased risk of <a href="/wiki/Nephrolithiasis" class="mw-redirect" title="Nephrolithiasis">nephrolithiasis</a>.<sup id="cite_ref-:33_58-0" class="reference"><a href="#cite_note-:33-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>In the first two weeks that the muscles are unloaded from carrying the weight of the human frame during space flight, whole muscle atrophy begins. Postural muscles contain more slow fibers, and are more prone to atrophy than non-postural muscle groups.<sup id="cite_ref-:23_57-1" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> The loss of muscle mass occurs because of imbalances in protein synthesis and breakdown. The loss of muscle mass is also accompanied by a loss of muscle strength, which was observed after only 2–5 days of spaceflight during the <a href="/wiki/Soyuz_3" title="Soyuz 3">Soyuz-3</a> and <a href="/wiki/Soyuz_8" title="Soyuz 8">Soyuz-8</a> missions.<sup id="cite_ref-:23_57-2" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> Decreases in the generation of contractile forces and whole muscle power have also been found in response to microgravity. </p><p>To counter the effects of microgravity on the musculoskeletal system, aerobic exercise is recommended. This often takes the form of in-flight cycling.<sup id="cite_ref-:23_57-3" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> A more effective regimen includes resistive exercises or the use of a penguin suit<sup id="cite_ref-:23_57-4" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> (contains sewn-in elastic bands to maintain a stretch load on antigravity muscles), centrifugation, and vibration.<sup id="cite_ref-:33_58-1" class="reference"><a href="#cite_note-:33-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> Centrifugation recreates Earth's gravitational force on the space station, in order to prevent <a href="/wiki/Muscle_atrophy" title="Muscle atrophy">muscle atrophy</a>. Centrifugation can be performed with centrifuges or by cycling along the inner wall of the space station.<sup id="cite_ref-:23_57-5" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> Whole body vibration has been found to reduce bone resorption through mechanisms that are unclear. Vibration can be delivered using exercise devices that use vertical displacements juxtaposed to a fulcrum, or by using a plate that oscillates on a vertical axis.<sup id="cite_ref-59" class="reference"><a href="#cite_note-59"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> The use of <a href="/wiki/Beta2-adrenergic_agonist" title="Beta2-adrenergic agonist">beta-2 adrenergic agonists</a> to increase muscle mass, and the use of essential amino acids in conjunction with resistive exercises have been proposed as pharmacologic means of combating muscle atrophy in space.<sup id="cite_ref-:23_57-6" class="reference"><a href="#cite_note-:23-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Cardiovascular_effects">Cardiovascular effects</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=18" title="Edit section: Cardiovascular effects"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure typeof="mw:File/Thumb"><span><video id="mwe_player_1" poster="//upload.wikimedia.org/wikipedia/commons/thumb/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/569px--StationLIFE_-_Cardiovascular_%28January_2016%29.webm.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="569" height="320" data-durationhint="1392" data-mwtitle="StationLIFE_-_Cardiovascular_(January_2016).webm" data-mwprovider="wikimediacommons" resource="/wiki/File:StationLIFE_-_Cardiovascular_(January_2016).webm"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.480p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="480p.vp9.webm" data-width="854" data-height="480" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.720p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="720p.vp9.webm" data-width="1280" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.1080p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="1080p.vp9.webm" data-width="1920" data-height="1080" /><source src="//upload.wikimedia.org/wikipedia/commons/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm" type="video/webm; codecs="vp9, opus"" data-width="1920" data-height="1080" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="426" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.360p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="360p.vp9.webm" data-width="640" data-height="360" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/0/03/StationLIFE_-_Cardiovascular_%28January_2016%29.webm/StationLIFE_-_Cardiovascular_%28January_2016%29.webm.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="640" data-height="360" /></video></span><figcaption>Astronaut Tracy Dyson talks about studies into cardiovascular health aboard the International Space Station.</figcaption></figure> <p>Next to the skeletal and muscular system, the cardiovascular system is less strained in weightlessness than on Earth and is de-conditioned during longer periods spent in space.<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> In a regular environment, gravity exerts a downward force, setting up a vertical hydrostatic gradient. When standing, some 'excess' fluid resides in vessels and tissues of the legs. In a micro-g environment, with the loss of a <a href="/wiki/Hydrostatic_pressure" class="mw-redirect" title="Hydrostatic pressure">hydrostatic gradient</a>, some fluid quickly redistributes toward the chest and upper body; sensed as 'overload' of circulating blood volume.<sup id="cite_ref-:42_61-0" class="reference"><a href="#cite_note-:42-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> In the micro-g environment, the newly sensed excess blood volume is adjusted by expelling excess fluid into tissues and cells (12-15% volume reduction) and <a href="/wiki/Red_blood_cell" title="Red blood cell">red blood cells</a> are adjusted downward to maintain a normal concentration (relative <a href="/wiki/Anemia" title="Anemia">anemia</a>).<sup id="cite_ref-:42_61-1" class="reference"><a href="#cite_note-:42-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> In the absence of gravity, venous blood will rush to the <a href="/wiki/Atrium_(heart)" title="Atrium (heart)">right atrium</a> because the force of gravity is no longer pulling the blood down into the vessels of the legs and abdomen, resulting in increased <a href="/wiki/Stroke_volume" title="Stroke volume">stroke volume</a>.<sup id="cite_ref-62" class="reference"><a href="#cite_note-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> These fluid shifts become more dangerous upon returning to a regular gravity environment as the body will attempt to adapt to the reintroduction of gravity. The reintroduction of gravity again will pull the fluid downward, but now there would be a deficit in both circulating fluid and red blood cells. The decrease in cardiac filling pressure and stroke volume during the orthostatic stress due to a decreased blood volume is what causes <a href="/wiki/Orthostatic_intolerance" title="Orthostatic intolerance">orthostatic intolerance</a>.<sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> Orthostatic intolerance can result in temporary loss of consciousness and posture, due to the lack of pressure and stroke volume.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> Some animal species have evolved physiological and anatomical features (such as high hydrostatic blood pressure and closer heart place to head) which enable them to counteract orthostatic blood pressure.<sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-66" class="reference"><a href="#cite_note-66"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> More chronic orthostatic intolerance can result in additional symptoms such as nausea, <a href="/wiki/Sleep_disorder" title="Sleep disorder">sleep problems</a>, and other vasomotor symptoms as well.<sup id="cite_ref-67" class="reference"><a href="#cite_note-67"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup> </p><p>Many studies on the physiological effects of weightlessness on the cardiovascular system are done in parabolic flights. It is one of the only feasible options to combine with human experiments, making parabolic flights the only way to investigate the true effects of the micro-g environment on a body without traveling into space.<sup id="cite_ref-:0_68-0" class="reference"><a href="#cite_note-:0-68"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> Parabolic flight studies have provided a broad range of results regarding changes in the cardiovascular system in a micro-g environment. Parabolic flight studies have increased the understanding of orthostatic intolerance and decreased peripheral blood flow suffered by astronauts returning to Earth. Due to the loss of blood to pump, the heart can atrophy in a micro-g environment. A weakened heart can result in low blood volume, low blood pressure and affect the body's ability to send oxygen to the brain without the individual becoming dizzy.<sup id="cite_ref-69" class="reference"><a href="#cite_note-69"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> <a href="/wiki/Heart_arrhythmia" class="mw-redirect" title="Heart arrhythmia">Heart rhythm disturbances</a> have also been seen among astronauts, but it is unclear whether this was a result of pre-existing conditions or an effect of the micro-g environment.<sup id="cite_ref-:1_70-0" class="reference"><a href="#cite_note-:1-70"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup> One current countermeasure includes drinking a salt solution, which increases the viscosity of blood and would subsequently increase blood pressure, which would mitigate post micro-g environment orthostatic intolerance. Another countermeasure includes administration of <a href="/wiki/Midodrine" title="Midodrine">midodrine</a>, which is a selective <a href="/wiki/Alpha-1_adrenergic_receptor" title="Alpha-1 adrenergic receptor">alpha-1</a> adrenergic agonist. Midodrine produces arterial and venous constriction resulting in an increase in blood pressure by <a href="/wiki/Baroreflex" title="Baroreflex">baroreceptor reflexes</a>.<sup id="cite_ref-:2_71-0" class="reference"><a href="#cite_note-:2-71"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Effects_on_non-human_organisms">Effects on non-human organisms</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=19" title="Edit section: Effects on non-human organisms"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Effect_of_spaceflight_on_the_human_body" title="Effect of spaceflight on the human body">Effect of spaceflight on the human body</a>, <a href="/wiki/Infection" title="Infection">Infection</a>, <a href="/wiki/Medical_treatment_during_spaceflight" title="Medical treatment during spaceflight">Medical treatment during spaceflight</a>, and <a href="/wiki/Space_medicine" title="Space medicine">Space medicine</a></div> <p>Russian scientists have observed differences between cockroaches conceived in space and their terrestrial counterparts. The space-conceived cockroaches grew more quickly, and also grew up to be faster and tougher.<sup id="cite_ref-72" class="reference"><a href="#cite_note-72"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup> </p><p>Chicken eggs that are put in microgravity two days after fertilization appear not to develop properly, whereas eggs put in microgravity more than a week after fertilization develop normally.<sup id="cite_ref-73" class="reference"><a href="#cite_note-73"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> </p><p>A 2006 Space Shuttle experiment found that <i><a href="/wiki/Salmonella_typhimurium" class="mw-redirect" title="Salmonella typhimurium">Salmonella typhimurium</a></i>, a bacterium that can cause food poisoning, became more virulent when cultivated in space.<sup id="cite_ref-ASU-20070923_74-0" class="reference"><a href="#cite_note-ASU-20070923-74"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> On April 29, 2013, scientists in Rensselaer Polytechnic Institute, funded by NASA, reported that, during <a href="/wiki/Spaceflight" title="Spaceflight">spaceflight</a> on the International Space Station, <a href="/wiki/Microbe" class="mw-redirect" title="Microbe">microbes</a> seem to adapt to the <a href="/wiki/Space_environment" title="Space environment">space environment</a> in ways "not observed on Earth" and in ways that "can lead to increases in growth and <a href="/wiki/Virulence" title="Virulence">virulence</a>".<sup id="cite_ref-PLos-20130429_75-0" class="reference"><a href="#cite_note-PLos-20130429-75"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> </p><p>Under certain test conditions, microbes have been observed to thrive in the near-weightlessness of space<sup id="cite_ref-GZM-20170913_76-0" class="reference"><a href="#cite_note-GZM-20170913-76"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> and to <a href="/wiki/Panspermia#Research_in_outer_space" title="Panspermia">survive in the vacuum of outer space</a>.<sup id="cite_ref-Dose_77-0" class="reference"><a href="#cite_note-Dose-77"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Horneck_78-0" class="reference"><a href="#cite_note-Horneck-78"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Commercial_applications">Commercial applications</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=20" title="Edit section: Commercial applications"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951" /><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Commercial_use_of_space" title="Commercial use of space">Commercial use of space</a>, <a href="/wiki/Scientific_research_on_the_International_Space_Station" title="Scientific research on the International Space Station">Scientific research on the International Space Station</a>, and <a href="/wiki/ESA_Scientific_Research_on_the_International_Space_Station" title="ESA Scientific Research on the International Space Station">ESA Scientific Research on the International Space Station</a></div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:Space_Fire.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/180px-Space_Fire.jpg" decoding="async" width="180" height="140" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/270px-Space_Fire.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/360px-Space_Fire.jpg 2x" data-file-width="2250" data-file-height="1750" /></a><figcaption><a href="/wiki/Candle" title="Candle">Candle</a> flame on Earth (left) versus in orbital conditions (right) </figcaption></figure> <div class="mw-heading mw-heading3"><h3 id="High-quality_crystals">High-quality crystals</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=21" title="Edit section: High-quality crystals"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>While not yet a commercial application, there has been interest in growing <a href="/wiki/Crystal" title="Crystal">crystals</a> in micro-g, as in a <a href="/wiki/Space_station" title="Space station">space station</a> or automated artificial <a href="/wiki/Satellite" title="Satellite">satellite</a> through <a href="/wiki/Low-gravity_process_engineering" title="Low-gravity process engineering">Low-gravity process engineering</a>, in an attempt to reduce crystal lattice defects.<sup id="cite_ref-79" class="reference"><a href="#cite_note-79"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> Such defect-free crystals may prove useful for certain microelectronic applications and also to produce crystals for subsequent <a href="/wiki/X-ray_crystallography" title="X-ray crystallography">X-ray crystallography</a>. </p><p>In 2017, an experiment on the ISS was conducted to crystallize the <a href="/wiki/Monoclonal_antibody" title="Monoclonal antibody">monoclonal antibody</a> therapeutic <a href="/wiki/Pembrolizumab" title="Pembrolizumab">Pembrolizumab</a>, where results showed more uniform and homogenous crystal particles compared to ground controls.<sup id="cite_ref-80" class="reference"><a href="#cite_note-80"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> Such uniform crystal particles can allow for the formulation of more concentrated, low-volume antibody therapies, something which can make them suitable for <a href="/wiki/Subcutaneous_administration" title="Subcutaneous administration">subcutaneous administration</a>, a less invasive approach compared to the current prevalent method of <a href="/wiki/Intravenous_therapy" title="Intravenous therapy">intravenous</a> administration.<sup id="cite_ref-Reichert_Prosise_Fischmann_Scapin_2019_p._81-0" class="reference"><a href="#cite_note-Reichert_Prosise_Fischmann_Scapin_2019_p.-81"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> </p> <ul class="gallery mw-gallery-traditional"> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Comparison2.jpg" class="mw-file-description" title="Comparison of boiling of water under Earth's gravity (1 g, left) and microgravity (right). The source of heat is in the lower part of the photograph."><img alt="Comparison of boiling of water under Earth's gravity (1 g, left) and microgravity (right). The source of heat is in the lower part of the photograph." src="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Comparison2.jpg/120px-Comparison2.jpg" decoding="async" width="120" height="39" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Comparison2.jpg/180px-Comparison2.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/5/5c/Comparison2.jpg/240px-Comparison2.jpg 2x" data-file-width="540" data-file-height="176" /></a></span></div> <div class="gallerytext">Comparison of boiling of water under Earth's gravity (1 g, left) and microgravity (right). The source of heat is in the lower part of the photograph.</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Space_Fire.jpg" class="mw-file-description" title="A comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found on the ISS (right)."><img alt="A comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found on the ISS (right)." src="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/120px-Space_Fire.jpg" decoding="async" width="120" height="93" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/180px-Space_Fire.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/74/Space_Fire.jpg/240px-Space_Fire.jpg 2x" data-file-width="2250" data-file-height="1750" /></a></span></div> <div class="gallerytext">A comparison between the combustion of a candle on Earth (left) and in a microgravity environment, such as that found on the <a href="/wiki/ISS" class="mw-redirect" title="ISS">ISS</a> (right).</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Crystals_grown_in_microgravity.jpg" class="mw-file-description" title="Protein crystals grown by American scientists on the Russian Space Station Mir in 1995.[82]"><img alt="Protein crystals grown by American scientists on the Russian Space Station Mir in 1995.[82]" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Crystals_grown_in_microgravity.jpg/120px-Crystals_grown_in_microgravity.jpg" decoding="async" width="120" height="90" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Crystals_grown_in_microgravity.jpg/180px-Crystals_grown_in_microgravity.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d1/Crystals_grown_in_microgravity.jpg/240px-Crystals_grown_in_microgravity.jpg 2x" data-file-width="926" data-file-height="698" /></a></span></div> <div class="gallerytext">Protein crystals grown by American scientists on the Russian Space Station <i><a href="/wiki/Mir" title="Mir">Mir</a></i> in 1995.<sup id="cite_ref-82" class="reference"><a href="#cite_note-82"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup></div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><a href="/wiki/File:Insulin_crystals_comparison.jpg" class="mw-file-description" title="Comparison of insulin crystals growth in outer space (left) and on Earth (right)."><img alt="Comparison of insulin crystals growth in outer space (left) and on Earth (right)." src="//upload.wikimedia.org/wikipedia/commons/thumb/a/af/Insulin_crystals_comparison.jpg/120px-Insulin_crystals_comparison.jpg" decoding="async" width="120" height="84" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/af/Insulin_crystals_comparison.jpg/180px-Insulin_crystals_comparison.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/af/Insulin_crystals_comparison.jpg/240px-Insulin_crystals_comparison.jpg 2x" data-file-width="300" data-file-height="210" /></a></span></div> <div class="gallerytext">Comparison of <a href="/wiki/Insulin" title="Insulin">insulin</a> crystals growth in outer space (left) and on Earth (right).</div> </li> <li class="gallerybox" style="width: 155px"> <div class="thumb" style="width: 150px; height: 150px;"><span typeof="mw:File"><span><video id="mwe_player_0" poster="//upload.wikimedia.org/wikipedia/commons/thumb/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/120px--ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.jpg" controls="" preload="none" data-mw-tmh="" class="mw-file-element" width="120" height="68" data-durationhint="242" data-mwtitle="ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm" data-mwprovider="wikimediacommons"><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.480p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="480p.vp9.webm" data-width="854" data-height="480" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.720p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="720p.vp9.webm" data-width="1280" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm" type="video/webm; codecs="vp9, opus"" data-width="1280" data-height="720" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.144p.mjpeg.mov" type="video/quicktime" data-transcodekey="144p.mjpeg.mov" data-width="256" data-height="144" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.240p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="240p.vp9.webm" data-width="426" data-height="240" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.360p.vp9.webm" type="video/webm; codecs="vp9, opus"" data-transcodekey="360p.vp9.webm" data-width="640" data-height="360" /><source src="//upload.wikimedia.org/wikipedia/commons/transcoded/d/dc/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm/ScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm.360p.webm" type="video/webm; codecs="vp8, vorbis"" data-transcodekey="360p.webm" data-width="640" data-height="360" /><track src="https://commons.wikimedia.org/w/api.php?action=timedtext&title=File%3AScienceCasts-_The_Zero_Gravity_Coffee_Cup.webm&lang=en&trackformat=vtt&origin=%2A" kind="subtitles" type="text/vtt" srclang="en" label="English ‪(en)‬" data-dir="ltr" /></video></span></span></div> <div class="gallerytext">Liquids may also behave differently than on Earth, as demonstrated in this video</div> </li> </ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Weightlessness&action=edit&section=22" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1266661725">.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}</style><ul role="navigation" aria-label="Portals" class="noprint portalbox portalborder portalright"> <li class="portalbox-entry"><span class="portalbox-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/28px-RocketSunIcon.svg.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/42px-RocketSunIcon.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d6/RocketSunIcon.svg/56px-RocketSunIcon.svg.png 2x" data-file-width="128" data-file-height="128" /></span></span></span><span class="portalbox-link"><a href="/wiki/Portal:Spaceflight" title="Portal:Spaceflight">Spaceflight portal</a></span></li></ul> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output 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Research on the International Space Station">ESA Scientific Research on the International Space Station</a></li> <li><a href="/wiki/European_Low_Gravity_Research_Association" title="European Low Gravity Research Association">European Low Gravity Research Association</a> (ELGRA)</li> <li><a href="/wiki/G-jitter" title="G-jitter">G-jitter</a></li> <li><a href="/wiki/Microgravity_University" title="Microgravity University">Microgravity University</a></li> <li><a href="/wiki/Parabolic_Flight" class="mw-redirect" title="Parabolic Flight">Reduced-gravity aircraft</a></li> <li><a href="/wiki/Scientific_research_on_the_International_Space_Station" title="Scientific research on the International Space Station">Scientific research on the International Space Station</a></li> <li><a href="/wiki/Space_adaptation_syndrome" title="Space adaptation syndrome">Space adaptation syndrome</a></li> <li><a href="/wiki/Space_manufacturing" title="Space manufacturing">Space manufacturing</a></li> <li><a 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.id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" 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Herbert Utz Verlag. p. 57. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9783896755001" title="Special:BookSources/9783896755001"><bdi>9783896755001</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Conceptual+Design+and+Flight+Simulation+of+Space+Stations&rft.pages=57&rft.pub=Herbert+Utz+Verlag&rft.date=1998&rft.isbn=9783896755001&rft.aulast=Bertrand&rft.aufirst=Reinhold&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DtqpqB5LPxygC%26q%3Dmicrogravity%2Btidal%2Bequations%26pg%3DPA57&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBaird2013" class="citation web cs1">Baird, Christopher S. (4 October 2013). <a rel="nofollow" class="external text" href="https://www.wtamu.edu/~cbaird/sq/2013/10/04/what-would-happen-if-you-fell-into-a-hole-that-went-through-the-center-of-the-earth/">"What would happen if you fell into a hole that went through the center of the earth?"</a>. <i>Science Questions with Surprising Answers</i><span class="reference-accessdate">. Retrieved <span class="nowrap">8 May</span> 2024</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Science+Questions+with+Surprising+Answers&rft.atitle=What+would+happen+if+you+fell+into+a+hole+that+went+through+the+center+of+the+earth%3F&rft.date=2013-10-04&rft.aulast=Baird&rft.aufirst=Christopher+S.&rft_id=https%3A%2F%2Fwww.wtamu.edu%2F~cbaird%2Fsq%2F2013%2F10%2F04%2Fwhat-would-happen-if-you-fell-into-a-hole-that-went-through-the-center-of-the-earth%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text">Depending on distance, "stationary" is meant relative to Earth or the Sun.</span> </li> <li id="cite_note-NYT-20140127-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-NYT-20140127_23-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFChang2014" class="citation news cs1">Chang, Kenneth (27 January 2014). <a rel="nofollow" class="external text" href="https://www.nytimes.com/2014/01/28/science/bodies-not-made-for-space.html">"Beings Not Made for Space"</a>. <i><a href="/wiki/New_York_Times" class="mw-redirect" title="New York Times">New York Times</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140128040558/http://www.nytimes.com/2014/01/28/science/bodies-not-made-for-space.html">Archived</a> from the original on 28 January 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">27 January</span> 2014</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+York+Times&rft.atitle=Beings+Not+Made+for+Space&rft.date=2014-01-27&rft.aulast=Chang&rft.aufirst=Kenneth&rft_id=https%3A%2F%2Fwww.nytimes.com%2F2014%2F01%2F28%2Fscience%2Fbodies-not-made-for-space.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFStepanekBlueParazynski2019" class="citation journal cs1">Stepanek, Jan; Blue, Rebecca S.; Parazynski, Scott (2019-03-14). Longo, Dan L. (ed.). <a rel="nofollow" class="external text" href="http://www.nejm.org/doi/10.1056/NEJMra1609012">"Space Medicine in the Era of Civilian Spaceflight"</a>. <i>New England Journal of Medicine</i>. <b>380</b> (11): <span class="nowrap">1053–</span>1060. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1056%2FNEJMra1609012">10.1056/NEJMra1609012</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0028-4793">0028-4793</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/30865799">30865799</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:76667295">76667295</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=New+England+Journal+of+Medicine&rft.atitle=Space+Medicine+in+the+Era+of+Civilian+Spaceflight&rft.volume=380&rft.issue=11&rft.pages=%3Cspan+class%3D%22nowrap%22%3E1053-%3C%2Fspan%3E1060&rft.date=2019-03-14&rft.issn=0028-4793&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A76667295%23id-name%3DS2CID&rft_id=info%3Apmid%2F30865799&rft_id=info%3Adoi%2F10.1056%2FNEJMra1609012&rft.aulast=Stepanek&rft.aufirst=Jan&rft.au=Blue%2C+Rebecca+S.&rft.au=Parazynski%2C+Scott&rft_id=http%3A%2F%2Fwww.nejm.org%2Fdoi%2F10.1056%2FNEJMra1609012&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-spp22_15-25"><span class="mw-cite-backlink">^ <a href="#cite_ref-spp22_15_25-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-spp22_15_25-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKanasManzey2008" class="citation book cs1">Kanas, Nick; Manzey, Dietrich (2008). "Basic Issues of Human Adaptation to Space Flight". <i>Space Psychology and Psychiatry</i>. Space Technology Library. Vol. 22. pp. <span class="nowrap">15–</span>48. <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/2008spp..book.....K">2008spp..book.....K</a>. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2F978-1-4020-6770-9_2">10.1007/978-1-4020-6770-9_2</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4020-6769-3" title="Special:BookSources/978-1-4020-6769-3"><bdi>978-1-4020-6769-3</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Basic+Issues+of+Human+Adaptation+to+Space+Flight&rft.btitle=Space+Psychology+and+Psychiatry&rft.series=Space+Technology+Library&rft.pages=%3Cspan+class%3D%22nowrap%22%3E15-%3C%2Fspan%3E48&rft.date=2008&rft_id=info%3Adoi%2F10.1007%2F978-1-4020-6770-9_2&rft_id=info%3Abibcode%2F2008spp..book.....K&rft.isbn=978-1-4020-6769-3&rft.aulast=Kanas&rft.aufirst=Nick&rft.au=Manzey%2C+Dietrich&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.jsc.nasa.gov/history/oral_histories/StevensonRE/RES_5-13-99.pdf">"NASA - Johnson Space Center History"</a> <span class="cs1-format">(PDF)</span>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120406090045/http://www.jsc.nasa.gov/history/oral_histories/StevensonRE/RES_5-13-99.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 2012-04-06<span class="reference-accessdate">. Retrieved <span class="nowrap">2012-05-10</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=NASA+-+Johnson+Space+Center+History&rft_id=http%3A%2F%2Fwww.jsc.nasa.gov%2Fhistory%2Foral_histories%2FStevensonRE%2FRES_5-13-99.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span>, pg 35, Johnson Space Center Oral History Project, interview with Dr. Robert Stevenson:<blockquote><p>"Jake Garn was sick, was pretty sick. I don't know whether we should tell stories like that. But anyway, Jake Garn, he has made a mark in the Astronaut Corps because he represents the maximum level of space sickness that anyone can ever attain, and so the mark of being totally sick and totally incompetent is one Garn. Most guys will get maybe to a tenth Garn, if that high. And within the Astronaut Corps, he forever will be remembered by that."</p></blockquote></span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFKelly2017" class="citation book cs1"><a href="/wiki/Scott_Kelly_(astronaut)" title="Scott Kelly (astronaut)">Kelly, Scott</a> (2017). <i><a href="/wiki/Endurance:_A_Year_in_Space,_a_Lifetime_of_Discovery" title="Endurance: A Year in Space, a Lifetime of Discovery">Endurance: A Year in Space, a Lifetime of Discovery</a></i>. With Margaret Lazarus Dean. Alfred A. Knopf, a division of Penguin Random House. p. 174. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/9781524731595" title="Special:BookSources/9781524731595"><bdi>9781524731595</bdi></a>. <q>One of the nice things about living in space is that exercise is part of your job ... If I don't exercise six days a week for at least a couple of hours a day, my bones will lose significant mass - 1 percent each month ... Our bodies are smart about getting rid of what's not needed, and my body has started to notice that my bones are not needed in zero gravity. Not having to support our weight, we lose muscle as well.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Endurance%3A+A+Year+in+Space%2C+a+Lifetime+of+Discovery&rft.pages=174&rft.pub=Alfred+A.+Knopf%2C+a+division+of+Penguin+Random+House&rft.date=2017&rft.isbn=9781524731595&rft.aulast=Kelly&rft.aufirst=Scott&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></span> </li> <li id="cite_note-hl-28"><span class="mw-cite-backlink">^ <a href="#cite_ref-hl_28-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-hl_28-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.spacefuture.com/habitat/healthfitness.shtml">Health Fitness</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120519042326/http://www.spacefuture.com/habitat/healthfitness.shtml">Archived</a> 2012-05-19 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>", <a href="/wiki/Space_Future" title="Space Future">Space Future</a></span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text">"<a rel="nofollow" class="external text" href="http://www.spacefuture.com/archive/the_pleasure_of_spaceflight.shtml">The Pleasure of Spaceflight</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20120221232737/http://www.spacefuture.com/archive/the_pleasure_of_spaceflight.shtml">Archived</a> 2012-02-21 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>", Toyohiro Akiyama, <i>Journal of Space Technology and Science</i>, Vol.9 No.1 spring 1993, pp.21-23</span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFBuckey2006" class="citation book cs1">Buckey, Jay C. 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(June 2021)">page needed</span></a></i>]</sup></span> </li> <li id="cite_note-72"><span class="mw-cite-backlink"><b><a href="#cite_ref-72">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.newscientist.com/blog/space/2008/01/mutant-super-cockroaches-from-space.html">"Mutant super-cockroaches from space"</a>. New Scientist. 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SpaceResearch - Human Physiology Research and the ISS: Staying Fit Along the Journey</a></li> <li>"<a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=iQOHRKKNNLQ">Why are astronauts weightless?</a>" Video explanation of the fallacy of "zero gravity".</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20160809074250/http://www.labflight.com/">Overview of microgravity applications and methods</a><sup><a href="/wiki/Template:Usurped/doc" title="Template:Usurped/doc">[usurped]</a></sup></li> <li><a rel="nofollow" class="external text" href="https://groups.google.com/group/sci.space.station/msg/8878d0bc915ae768?dmode=source">Criticism of the terms "Zero Gravity" and "Microgravity"</a>, a persuasion to use terminology that reflects accurate physics (sci.space post).</li> <li><a rel="nofollow" class="external text" href="http://libarchstor.uah.edu:8081/repositories/2/resources/147">Microgravity Collection, The University of Alabama in Huntsville Archives and Special Collections</a></li> <li><a rel="nofollow" class="external text" href="http://bio.au-kbc.org/faculty/suvro/space.htm">Space Biology Research at AU-KBC Research Centre</a></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFJhalaKaleSingh2014" class="citation journal cs1">Jhala, Dhwani; Kale, Raosaheb; Singh, Rana (2014). "Microgravity Alters Cancer Growth and Progression". <i>Current Cancer Drug Targets</i>. <b>14</b> (4): <span class="nowrap">394–</span>406. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2174%2F1568009614666140407113633">10.2174/1568009614666140407113633</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/24720362">24720362</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Current+Cancer+Drug+Targets&rft.atitle=Microgravity+Alters+Cancer+Growth+and+Progression&rft.volume=14&rft.issue=4&rft.pages=%3Cspan+class%3D%22nowrap%22%3E394-%3C%2Fspan%3E406&rft.date=2014&rft_id=info%3Adoi%2F10.2174%2F1568009614666140407113633&rft_id=info%3Apmid%2F24720362&rft.aulast=Jhala&rft.aufirst=Dhwani&rft.au=Kale%2C+Raosaheb&rft.au=Singh%2C+Rana&rfr_id=info%3Asid%2Fen.wikipedia.org%3AWeightlessness" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222" /><cite id="CITEREFTirumalaiKarouiaTranStepanov2017" class="citation journal cs1">Tirumalai, Madhan R.; Karouia, Fathi; Tran, Quyen; Stepanov, Victor G.; Bruce, Rebekah J.; Ott, C. Mark; Pierson, Duane L.; Fox, George E. (December 2017). <a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460176">"The adaptation of Escherichia coli cells grown in simulated microgravity for an extended period is both phenotypic and genomic"</a>. <i>npj Microgravity</i>. <b>3</b> (1): 15. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1038%2Fs41526-017-0020-1">10.1038/s41526-017-0020-1</a>. <a href="/wiki/PMC_(identifier)" class="mw-redirect" title="PMC (identifier)">PMC</a> <span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460176">5460176</a></span>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/28649637">28649637</a>.</cite><span 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.navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Space_medicine" title="Template:Space medicine"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Space_medicine" title="Template talk:Space medicine"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Space_medicine" title="Special:EditPage/Template:Space medicine"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Space_medicine73" style="font-size:114%;margin:0 4em"><a href="/wiki/Space_medicine" title="Space medicine">Space medicine</a></div></th></tr><tr><th scope="row" class="navbox-group" style="text-align:center;;width:1%">Main areas</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Artificial_gravity" title="Artificial gravity">Artificial gravity</a></li> <li><a href="/wiki/Astronautical_hygiene" title="Astronautical hygiene">Astronautical hygiene</a></li> <li><a href="/wiki/Bioastronautics" title="Bioastronautics">Bioastronautics</a></li> <li><a href="/wiki/Neuroscience_in_space" title="Neuroscience in space">Neuroscience in space</a></li> <li><a href="/wiki/Space_exposure" class="mw-redirect" title="Space exposure">Space exposure</a></li> <li><a href="/wiki/Space_food" title="Space food">Space food</a></li> <li><a href="/wiki/Space_nursing" title="Space nursing">Space nursing</a></li> <li><a href="/wiki/Space_weather" title="Space weather">Space weather</a></li> <li><a class="mw-selflink selflink">Weightlessness</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align:center;;width:1%">Illness and injuries</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Asthenization" class="mw-redirect" title="Asthenization">Asthenization</a></li> <li><a href="/wiki/Ebullism" title="Ebullism">Ebullism</a></li> <li><a href="/wiki/Illness_and_injuries_during_spaceflight" title="Illness and injuries during spaceflight">Illness and injuries during spaceflight</a></li> <li><a href="/wiki/Medical_treatment_during_spaceflight" title="Medical treatment during spaceflight">Medical treatment during spaceflight</a></li> <li><a href="/wiki/Space_adaptation_syndrome" title="Space adaptation syndrome">Space adaptation syndrome</a></li> <li><a href="/wiki/Space_and_survival" title="Space and survival">Space and survival</a></li> <li><a href="/wiki/Spaceflight_osteopenia" title="Spaceflight osteopenia">Spaceflight osteopenia</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align:center;;width:1%">Organizations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Aerospace_Medical_Association" title="Aerospace Medical Association">Aerospace Medical Association</a></li> <li><a href="/wiki/National_Space_Biomedical_Research_Institute" title="National Space Biomedical Research Institute">National Space Biomedical Research Institute</a></li> <li><a href="/wiki/Rubicon_Foundation" title="Rubicon Foundation">Rubicon Foundation</a></li> <li><a href="/wiki/Space_Nursing_Society" title="Space Nursing Society">Space Nursing Society</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align:center;;width:1%">Other topics</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Adverse_health_effects_from_lunar_dust_exposure" class="mw-redirect" title="Adverse health effects from lunar dust exposure">Adverse health effects from lunar dust exposure</a></li> <li><a href="/wiki/Cardiac_rhythm_problems_during_space_flight" class="mw-redirect" title="Cardiac rhythm problems during space flight">Cardiac rhythm problems during space flight</a></li> <li><a href="/wiki/Central_nervous_system_effects_from_radiation_exposure_during_spaceflight" title="Central nervous system effects from radiation exposure during spaceflight">Central nervous system effects from radiation exposure during spaceflight</a></li> <li><a href="/wiki/Effect_of_spaceflight_on_the_human_body" title="Effect of spaceflight on the human body">Effect of spaceflight on the human body</a></li> <li><a href="/wiki/Effects_of_sleep_deprivation_in_space" title="Effects of sleep deprivation in space">Effects of sleep deprivation in space</a></li> <li><a href="/wiki/Epidemiology_data_for_low-linear_energy_transfer_radiation" title="Epidemiology data for low-linear energy transfer radiation">Epidemiology data for low-linear energy transfer radiation</a></li> <li><a href="/wiki/Sleep_in_space" title="Sleep in space">Sleep in space</a></li> <li><a href="/wiki/Health_threat_from_cosmic_rays" class="mw-redirect" title="Health threat from cosmic rays">Health threat from cosmic rays</a></li> <li><a href="/wiki/Intervertebral_disc_damage_and_spaceflight" title="Intervertebral disc damage and spaceflight">Intervertebral disc damage and spaceflight</a></li> <li><a href="/wiki/List_of_microorganisms_tested_in_outer_space" title="List of microorganisms tested in outer space">List of microorganisms tested in outer space</a></li> <li><a href="/wiki/Psychological_and_sociological_effects_of_spaceflight" title="Psychological and sociological effects of spaceflight">Psychological and sociological effects of spaceflight</a></li> <li><a href="/wiki/Radiobiology_evidence_for_protons_and_HZE_nuclei" title="Radiobiology evidence for protons and HZE nuclei">Radiobiology evidence for protons and HZE nuclei</a></li> <li><a href="/wiki/Reduced_muscle_mass,_strength_and_performance_in_space" class="mw-redirect" title="Reduced muscle mass, strength and performance in space">Reduced muscle mass, strength and performance in space</a></li> <li><a href="/wiki/Renal_stone_formation_in_space" title="Renal stone formation in space">Renal stone formation in space</a></li> <li><a href="/wiki/Spaceflight_radiation_carcinogenesis" class="mw-redirect" title="Spaceflight radiation carcinogenesis">Spaceflight radiation carcinogenesis</a></li> <li><a href="/wiki/Team_composition_and_cohesion_in_spaceflight_missions" class="mw-redirect" title="Team composition and cohesion in spaceflight missions">Team composition and cohesion in spaceflight missions</a></li> <li><a href="/wiki/Visual_impairment_due_to_intracranial_pressure" class="mw-redirect" title="Visual impairment due to intracranial pressure">Visual impairment due to intracranial pressure</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374" /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235" /></div><div role="navigation" class="navbox" aria-labelledby="Spaceflight370" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2" style="text-align: center;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374" /><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231" /><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Spaceflight" title="Template:Spaceflight"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Spaceflight" title="Template talk:Spaceflight"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Spaceflight" title="Special:EditPage/Template:Spaceflight"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Spaceflight370" style="font-size:114%;margin:0 4em"><a href="/wiki/Spaceflight" title="Spaceflight">Spaceflight</a></div></th></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">General</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Orbital_mechanics" title="Orbital mechanics">Astrodynamics</a></li> <li><a href="/wiki/History_of_spaceflight" title="History of spaceflight">History</a> <ul><li><a href="/wiki/Timeline_of_spaceflight" title="Timeline of spaceflight">Timeline</a></li> <li><a href="/wiki/Space_Race" title="Space Race">Space Race</a></li> <li><a href="/wiki/List_of_spaceflight_records" title="List of spaceflight records">Records</a></li> <li><a href="/wiki/List_of_spaceflight-related_accidents_and_incidents" title="List of spaceflight-related accidents and incidents">Accidents and incidents</a></li></ul></li> <li><a href="/wiki/Space_launch" title="Space launch">Space launch</a></li> <li><a href="/wiki/Space_policy" title="Space policy">Space policy</a> <ul><li><a href="/wiki/Category:Space_programme_of_Australia" title="Category:Space programme of Australia">Australia</a></li> <li><a href="/wiki/Chinese_space_program" title="Chinese space program">China</a></li> <li><a href="/wiki/European_Space_Agency_Science_Programme" title="European Space Agency Science Programme">European Space Agency</a></li> <li><a href="/wiki/European_Union_Space_Programme" title="European Union Space Programme">European Union</a></li> <li><a href="/wiki/ISRO" title="ISRO">India</a></li> <li><a href="/wiki/Japanese_space_program" title="Japanese space program">Japan</a></li> <li><a href="/wiki/North_Korean_space_program" title="North Korean space program">North Korea</a></li> <li><a href="/wiki/South_Korean_space_program" title="South Korean space program">South Korea</a></li> <li><a href="/wiki/Roscosmos" title="Roscosmos">Russia</a></li> <li><a href="/wiki/Soviet_space_program" title="Soviet space program">Soviet Union</a></li> <li><a href="/wiki/Space_policy_of_the_United_States" title="Space policy of the United States">United States</a></li></ul></li> <li><a href="/wiki/Space_law" title="Space law">Space law</a> <ul><li><a href="/wiki/Outer_Space_Treaty" title="Outer Space Treaty">Outer Space Treaty</a></li> <li><a href="/wiki/Rescue_Agreement" title="Rescue Agreement">Rescue Agreement</a></li> <li><a href="/wiki/Space_Liability_Convention" title="Space Liability Convention">Space Liability Convention</a></li> <li><a href="/wiki/Registration_Convention" title="Registration Convention">Registration Convention</a></li> <li><a href="/wiki/Moon_Treaty" title="Moon Treaty">Moon Treaty</a></li></ul></li> <li><a href="/wiki/Space_warfare" title="Space warfare">Space warfare</a> <ul><li><a href="/wiki/Space_command" title="Space command">Space command</a></li> <li><a href="/wiki/Space_force" title="Space force">Space force</a></li> <li><a href="/wiki/Militarisation_of_space" title="Militarisation of space">Militarisation of space</a></li></ul></li> <li><a href="/wiki/Private_spaceflight" title="Private spaceflight">Private spaceflight</a> <ul><li><a href="/wiki/Billionaire_space_race" title="Billionaire space race">Billionaire space race</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="/wiki/Outline_of_space_science" title="Outline of space science">Applications</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Astronomy" title="Astronomy">Astronomy</a></li> <li><a href="/wiki/Earth_observation_satellite" title="Earth observation satellite">Earth observation</a> <ul><li><a href="/wiki/Remote_sensing_(archaeology)" class="mw-redirect" title="Remote sensing (archaeology)">Archaeology</a></li> <li><a href="/wiki/Satellite_imagery" title="Satellite imagery">Imagery and mapping</a></li> <li><a href="/wiki/Reconnaissance_satellite" title="Reconnaissance satellite">Reconnaissance</a></li> <li><a href="/wiki/Weather_satellite" title="Weather satellite">Weather and environment monitoring</a></li></ul></li> <li><a href="/wiki/Communications_satellite" title="Communications satellite">Communications satellite</a> <ul><li><a href="/wiki/Satellite_Internet_access" title="Satellite Internet access">Internet</a></li> <li><a href="/wiki/Satellite_radio" title="Satellite radio">Radio</a></li> <li><a href="/wiki/Satellite_phone" title="Satellite phone">Telephone</a></li> <li><a href="/wiki/Satellite_television" title="Satellite television">Television</a></li></ul></li> <li><a href="/wiki/Satellite_navigation" title="Satellite navigation">Satellite navigation</a></li> <li><a href="/wiki/Commercial_use_of_space" title="Commercial use of space">Commercial use of space</a></li> <li><a href="/wiki/Space_launch_market_competition" title="Space launch market competition">Space launch market competition</a></li> <li><a href="/wiki/Space_architecture" title="Space architecture">Space architecture</a></li> <li><a href="/wiki/Space_exploration" title="Space exploration">Space exploration</a></li> <li><a href="/wiki/Space_research" title="Space research">Space research</a></li> <li><a href="/wiki/Space_technology" title="Space technology">Space technology</a></li> <li><a href="/wiki/Space_weather" title="Space weather">Space weather</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="/wiki/Human_spaceflight" title="Human spaceflight">Human spaceflight</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">General</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Astronaut" title="Astronaut">Astronaut</a> <ul><li><a href="/wiki/Commercial_astronaut" title="Commercial astronaut">commercial</a></li></ul></li> <li><a href="/wiki/Life-support_system" title="Life-support system">Life-support system</a> <ul><li><a href="/wiki/Animals_in_space" title="Animals in space">Animals in space</a></li> <li><a href="/wiki/Bioastronautics" title="Bioastronautics">Bioastronautics</a></li> <li><a href="/wiki/Space_suit" title="Space suit">Space suit</a></li></ul></li> <li><a href="/wiki/Extravehicular_activity" title="Extravehicular activity">Extravehicular activity</a></li> <li><a href="/wiki/Overview_effect" title="Overview effect">Overview effect</a></li> <li><a class="mw-selflink selflink">Weightlessness</a></li> <li><a href="/wiki/Space_toilet" title="Space toilet">Space toilet</a></li> <li><a href="/wiki/Space_tourism" title="Space tourism">Space tourism</a></li> <li><a href="/wiki/Space_colonization" title="Space colonization">Space colonization</a></li> <li><a href="/wiki/Space_diving" title="Space diving">Space diving</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Programs</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Vostok_programme" title="Vostok programme">Vostok</a></li> <li><a href="/wiki/Project_Mercury" title="Project Mercury">Mercury</a></li> <li><a href="/wiki/Voskhod_programme" title="Voskhod programme">Voskhod</a></li> <li><a href="/wiki/Project_Gemini" title="Project Gemini">Gemini</a></li> <li><a href="/wiki/Soyuz_programme" title="Soyuz programme">Soyuz</a></li> <li><a href="/wiki/Apollo_program" title="Apollo program">Apollo</a> <ul><li><a href="/wiki/Skylab" title="Skylab">Skylab</a></li> <li><a href="/wiki/Apollo%E2%80%93Soyuz" title="Apollo–Soyuz">Apollo–Soyuz</a></li></ul></li> <li><a href="/wiki/Space_Shuttle_program" title="Space Shuttle program">Space Shuttle</a></li> <li><a href="/wiki/Mir" title="Mir">Mir</a> <ul><li><a href="/wiki/Shuttle%E2%80%93Mir_program" title="Shuttle–Mir program">Shuttle–Mir</a></li></ul></li> <li><a href="/wiki/International_Space_Station" title="International Space Station">International Space Station</a></li> <li><a href="/wiki/China_Manned_Space_Program" title="China Manned Space Program">Shenzhou</a></li> <li><a href="/wiki/Tiangong_program" title="Tiangong program">Tiangong</a></li> <li><a href="/wiki/New_Shepard" title="New Shepard">New Shepard</a></li> <li><a href="/wiki/Artemis_program" title="Artemis program">Artemis</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%;text-align: center;">Health issues</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Effect_of_spaceflight_on_the_human_body" title="Effect of spaceflight on the human body">Effect of spaceflight on the human body</a> <ul><li><a href="/wiki/Space_adaptation_syndrome" title="Space adaptation syndrome">Space adaptation syndrome</a></li></ul></li> <li><a href="/wiki/Health_threat_from_cosmic_rays" class="mw-redirect" title="Health threat from cosmic rays">Health threat from cosmic rays</a></li> <li><a href="/wiki/Space_psychology" title="Space psychology">Space psychology</a> <ul><li><a href="/wiki/Psychological_and_sociological_effects_of_spaceflight" title="Psychological and sociological effects of spaceflight">Psychological and sociological effects</a></li></ul></li> <li><a href="/wiki/Space_and_survival" title="Space and survival">Space and survival</a></li> <li><a href="/wiki/Space_medicine" title="Space medicine">Space medicine</a></li> <li><a href="/wiki/Space_nursing" title="Space nursing">Space nursing</a></li> <li><a href="/wiki/Space_sexology" title="Space sexology">Space sexology</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="/wiki/Spacecraft" title="Spacecraft">Spacecraft</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Launch_vehicle" title="Launch vehicle">Launch vehicle</a></li> <li><a href="/wiki/Rocket" title="Rocket">Rocket</a></li> <li><a href="/wiki/Space_capsule" title="Space capsule">Space capsule</a> <ul><li><a href="/wiki/Orbital_module" title="Orbital module">Orbital module</a></li> <li><a href="/wiki/Reentry_capsule" title="Reentry capsule">Reentry capsule</a></li> <li><a href="/wiki/Service_module" title="Service module">Service module</a></li></ul></li> <li><a href="/wiki/Spaceplane" title="Spaceplane">Spaceplane</a></li> <li><a href="/wiki/Robotic_spacecraft" class="mw-redirect" title="Robotic spacecraft">Robotic spacecraft</a> <ul><li><a href="/wiki/Satellite" title="Satellite">Satellite</a></li> <li><a href="/wiki/Space_probe" class="mw-redirect" title="Space probe">Space probe</a></li> <li><a href="/wiki/Lander_(spacecraft)" title="Lander (spacecraft)">Lander</a></li> <li><a href="/wiki/Rover_(space_exploration)" title="Rover (space exploration)">Rover</a></li> <li><a href="/wiki/Self-replicating_spacecraft" title="Self-replicating spacecraft">Self-replicating spacecraft</a></li> <li><a href="/wiki/Space_telescope" title="Space telescope">Space telescope</a></li></ul></li> <li><a href="/wiki/Spacecraft_propulsion" title="Spacecraft propulsion">Spacecraft propulsion</a> <ul><li><a href="/wiki/Rocket_engine" title="Rocket engine">Rocket engine</a></li> <li><a href="/wiki/Spacecraft_electric_propulsion" title="Spacecraft electric propulsion">Electric propulsion</a></li> <li><a href="/wiki/Solar_sail" title="Solar sail">Solar sail</a></li> <li><a href="/wiki/Gravity_assist" title="Gravity assist">Gravity assist</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%">Destinations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Sub-orbital_spaceflight" title="Sub-orbital spaceflight">Sub-orbital</a></li> <li><a href="/wiki/Orbital_spaceflight" title="Orbital spaceflight">Orbital</a> <ul><li><a href="/wiki/Geocentric_orbit" title="Geocentric orbit">Geocentric</a></li> <li><a href="/wiki/Geosynchronous_orbit" title="Geosynchronous orbit">Geosynchronous</a></li></ul></li> <li><a href="/wiki/Interplanetary_spaceflight" title="Interplanetary spaceflight">Interplanetary</a></li> <li><a href="/wiki/Interstellar_travel" title="Interstellar travel">Interstellar</a></li> <li><a href="/wiki/Intergalactic_travel" title="Intergalactic travel">Intergalactic</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="text-align: center;;width:1%"><a href="/wiki/Space_launch" title="Space launch">Space launch</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Direct_ascent" title="Direct ascent">Direct ascent</a></li> <li><a href="/wiki/Escape_velocity" title="Escape velocity">Escape velocity</a></li> <li><a href="/wiki/Expendable_launch_system" title="Expendable launch system">Expendable</a> and <a href="/wiki/Reusable_launch_vehicle" title="Reusable launch vehicle">reusable launch systems</a></li> <li><a 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