Editing Atmospheric entry (section)

==Uncontrolled and unprotected entries==
{{See also|List of reentering space debris}}
Of satellites that reenter, approximately 10–40% of the mass of the object may reach the surface of the Earth.<ref>{{Cite web|url=http://www.aerospace.org/cords/spacecraft-reentry/how-much-material-from-a-satellite-will-survive-reentry/|archive-url=https://web.archive.org/web/20140302115307/http://www.aerospace.org/cords/spacecraft-reentry/how-much-material-from-a-satellite-will-survive-reentry/ |url-status=dead |title=Spacecraft Reentry FAQ: How much material from a satellite will survive reentry?|archive-date=March 2, 2014}}</ref> On average, about one catalogued object reentered per day {{asof|2014|lc=y}}.<ref>{{Cite web|url=https://www.nasa.gov/news/debris_faq.html|archive-url=https://web.archive.org/web/20140311033244/http://www.nasa.gov/news/debris_faq.html |url-status=dead |title=NASA - Frequently Asked Questions: Orbital Debris|archive-date=March 11, 2014|website=www.nasa.gov}}</ref>

Because the Earth's surface is predominantly water, most objects that survive reentry land in one of the world's oceans. The estimated chance that a given person would get hit and injured during their lifetime is around 1 in a trillion.<ref>{{cite web|url=http://www.aerospace.org/cords/spacecraft-reentry/|title=Animation52-desktop|website=www.aerospace.org|access-date=2013-03-04|archive-url=https://web.archive.org/web/20140302150713/http://www.aerospace.org/cords/spacecraft-reentry/|archive-date=2014-03-02|url-status=dead}}</ref>

On January 24, 1978, the [[Soviet Union|Soviet]] [[Kosmos 954]] ({{convert|3800|kg|disp=sqbr}}) reentered and crashed near [[Great Slave Lake]] in the [[Northwest Territories]] of Canada. The satellite was nuclear-powered and left radioactive debris near its impact site.<ref name="jaxa">{{cite web|url=http://www.jaxa.jp/library/space_law/chapter_3/3-2-2-1_e.html|title=3-2-2-1 Settlement of Claim between Canada and the Union of Soviet Socialist Republics for Damage Caused by "Cosmos 954" (Released on April 2, 1981)|website=www.jaxa.jp|access-date=December 28, 2010|archive-date=September 30, 2019|archive-url=https://web.archive.org/web/20190930070151/http://www.jaxa.jp/library/space_law/chapter_3/3-2-2-1_e.html|url-status=live}}</ref>

On July 11, 1979, the US [[Skylab]] space station ({{convert|77100|kg|disp=sqbr}}) reentered and spread debris across the Australian [[Outback]].<ref>{{cite book|last=Hanslmeier|first=Arnold|title=The sun and space weather|date=2002|publisher=Kluwer Academic Publishers|location=Dordrecht; Boston|isbn=9781402056048|page=269}}</ref> The reentry was a major media event largely due to the Cosmos 954 incident, but not viewed as much as a potential disaster since it did not carry toxic nuclear or [[hydrazine]] fuel. NASA had originally hoped to use a [[Space Shuttle]] mission to either extend its life or enable a controlled reentry, but delays in the Shuttle program, plus unexpectedly high solar activity, made this impossible.<ref>{{cite book|last=Lamprecht|first=Jan|title=Hollow planets : a feasibility study of possible hollow worlds|date=1998|publisher=World Wide Pub.|location=Austin, Texas|isbn=9780620219631|page=326}}</ref><ref>{{cite book|last=Elkins-Tanton|first=Linda|title=The Sun, Mercury, and Venus|date=2006|publisher=Chelsea House|location=New York|isbn=9780816051939|page=56}}</ref>

On February 7, 1991, the Soviet [[Salyut 7]] space station ({{convert|19820|kg|disp=sqbr}}), with the [[Kosmos 1686]] module ({{convert|20000|kg|disp=sqbr}}) attached, reentered and scattered debris over the town of [[Capitán Bermúdez]], Argentina.<ref>{{Cite web|url=http://www.aero.org/capabilities/cords/faq8.html|archive-url=https://web.archive.org/web/20120513052250/http://www.aero.org/capabilities/cords/faq8.html |url-status=dead |title=aero.org, ''Spacecraft Reentry FAQ:''|archive-date=May 13, 2012}}</ref><ref name="auto"/><ref>[https://www.nytimes.com/1991/02/07/world/salyut-7-soviet-station-in-space-falls-to-earth-after-9-year-orbit.html "Salyut 7, Soviet Station in Space, Falls to Earth After 9-Year Orbit"] {{Webarchive|url=https://web.archive.org/web/20161118131918/http://www.nytimes.com/1991/02/07/world/salyut-7-soviet-station-in-space-falls-to-earth-after-9-year-orbit.html |date=November 18, 2016 }} ''New York Times''</ref> The station had been boosted to a higher orbit in August 1986 in an attempt to keep it up until 1994, but in a scenario similar to Skylab, the planned [[Buran programme|Buran shuttle]] was cancelled and high solar activity caused it to come down sooner than expected.

On September 7, 2011, NASA announced the impending uncontrolled reentry of the [[Upper Atmosphere Research Satellite]] ({{convert|6540|kg|disp=sqbr}}) and noted that there was a small risk to the public.<ref>{{cite news | title=Huge Defunct Satellite to Plunge to Earth Soon, NASA Says | work=Space.com | url=http://www.space.com/12859-nasa-satellite-falling-space-debris-uars.html | author=David, Leonard | date=7 September 2011 | access-date=10 September 2011 | archive-date=May 6, 2021 | archive-url=https://web.archive.org/web/20210506183208/https://www.space.com/12859-nasa-satellite-falling-space-debris-uars.html | url-status=live }}</ref> The decommissioned satellite reentered the atmosphere on September 24, 2011, and some pieces are presumed to have crashed into the South [[Pacific Ocean]] over a debris field {{convert|500|mi}} long.<ref name="finalupdate">{{cite web |url=http://www.nasa.gov/mission_pages/uars/index.html |title=Final Update: NASA's UARS Re-enters Earth's Atmosphere |access-date=2011-09-27 |archive-date=February 25, 2018 |archive-url=https://web.archive.org/web/20180225204106/https://www.nasa.gov/mission_pages/uars/index.html |url-status=live }}</ref>

On April 1, 2018, the Chinese [[Tiangong-1]] space station ({{convert|8510|kg|disp=sqbr}}) reentered over the Pacific Ocean, halfway between Australia and South America.<ref>{{Cite web |url=http://www.aerospace.org/cords/reentry-predictions/tiangong-1-reentry/ |title=aerospace.org ''Tiangong-1 Reentry'' |access-date=2018-04-02 |archive-url=https://web.archive.org/web/20180404003614/http://www.aerospace.org/cords/reentry-predictions/tiangong-1-reentry/ |archive-date=2018-04-04 |url-status=dead }}</ref> The [[China Manned Space Engineering Office]] had intended to control the reentry, but lost [[telemetry]] and control in March 2017.<ref name="rogue">{{cite news|last=Jones|first=Morris|date=30 March 2016|title=Has Tiangong 1 gone rogue|url=http://www.spacedaily.com/reports/Has_Tiangong_1_gone_rogue_999.html|newspaper=Space Daily|access-date=22 September 2016|archive-date=September 13, 2017|archive-url=https://web.archive.org/web/20170913231010/http://www.spacedaily.com/reports/Has_Tiangong_1_gone_rogue_999.html|url-status=live}}</ref>

On May 11, 2020, the core stage of Chinese [[Long March 5|Long March 5B]] ([[COSPAR ID]] 2020-027C) weighing roughly {{convert|20000|kg|disp=sqbr||abbr=}}) made an uncontrolled reentry over the Atlantic Ocean, near West African coast.<ref>{{cite tweet|user=18SPCS |number=1259891636189839360|date=11 May 2020|title=#18SPCS has confirmed the reentry of the CZ-5B R/B (#45601, 2020-027C) at 08:33 PDT on 11 May, over the Atlantic Ocean. The #CZ5B launched China's test crew capsule on 5 May 2020. #spaceflightsafety|author-link=|access-date=11 May 2020 |language=en|author=((18 Space Control Squadron)) |url-status=live |archive-url=https://web.archive.org/web/20200514104807/https://twitter.com/18SPCS/status/1259891636189839360 |archive-date= May 14, 2020 }}</ref><ref>{{Cite web|title=China's massive Long March 5B's rocket falls out of orbit over Atlantic Ocean |website=Spaceflight Now |date=May 11, 2020 |url=https://spaceflightnow.com/2020/05/11/chinas-massive-long-march-5bs-rocket-falls-out-of-orbit-over-ocean/|last=Clark|first=Stephen|language=en-US|access-date=2020-05-12|archive-date=May 14, 2020|archive-url=https://web.archive.org/web/20200514211903/https://spaceflightnow.com/2020/05/11/chinas-massive-long-march-5bs-rocket-falls-out-of-orbit-over-ocean/|url-status=live}}</ref> Few pieces of rocket debris reportedly survived reentry and fell over at least two villages in [[Ivory Coast]].<ref>{{Cite web|title=Bridenstine Criticizes Uncontrolled Long March 5B Stage Reentry |website=Parabolic Arc |first1=Doug |last1=Messier |date=May 15, 2020 |url=http://www.parabolicarc.com/2020/05/15/bridenstine-criticizes-uncontrolled-long-march-5b-stage-reentry/|language=en-US|access-date=2020-05-16|archive-date=May 21, 2020|archive-url=https://web.archive.org/web/20200521234307/http://www.parabolicarc.com/2020/05/15/bridenstine-criticizes-uncontrolled-long-march-5b-stage-reentry/|url-status=dead }}</ref><ref>{{Cite web|title=Chinese Rocket Debris May Have Fallen On Several African Villages After An Uncontrolled Re-Entry|url=https://www.forbes.com/sites/jonathanocallaghan/2020/05/12/parts-of-a-chinese-rocket-may-have-fallen-on-an-african-village/ |url-access=subscription |date=May 12, 2020 |last=O'Callaghan|first=Jonathan|website=Forbes|language=en|access-date=2020-05-13|archive-date=May 12, 2020|archive-url=https://web.archive.org/web/20200512235929/https://www.forbes.com/sites/jonathanocallaghan/2020/05/12/parts-of-a-chinese-rocket-may-have-fallen-on-an-african-village/|url-status=live}}</ref>

On May 8, 2021, the core stage of Chinese [[Long March 5|Long March 5B]] ([[COSPAR ID]] 2021-0035B) weighing {{convert|23000|kg|disp=sqbr||abbr=}}) made an uncontrolled reentry, just west of the Maldives in the Indian Ocean (approximately 72.47°E longitude and 2.65°N latitude).<ref>{{Cite web|title=CZ-5B R/B |website=N2YO.com |url=https://www.n2yo.com/satellite/?s=48275|language=en-US|access-date=2021-05-09|archive-date=July 23, 2021|archive-url=https://web.archive.org/web/20210723163817/https://www.n2yo.com/satellite/?s=48275|url-status=live}}</ref> Witnesses reported rocket debris as far away as the Arabian peninsula.<ref>{{Cite web|title=Huge Chinese rocket booster falls to Earth over Arabian Peninsula |url=https://www.space.com/chinese-rocket-booster-long-march-5b-space-junk-crash|last=Wall|first=Mike|website=[[Space.com]]|date=May 9, 2021|language=en-US|access-date=2021-05-09|archive-date=July 23, 2021|archive-url=https://web.archive.org/web/20210723163815/https://www.space.com/chinese-rocket-booster-long-march-5b-space-junk-crash|url-status=live}}</ref>

===Deorbit disposal===
[[Salyut 1]], the world's first space station, was deliberately de-orbited into the Pacific Ocean in 1971 following the [[Soyuz 11]] accident. Its successor, [[Salyut 6]], was de-orbited in a controlled manner as well.

On June 4, 2000, the [[Compton Gamma Ray Observatory]] was deliberately de-orbited after one of its gyroscopes failed. The debris that did not burn up fell harmlessly into the Pacific Ocean. The observatory was still operational, but the failure of another gyroscope would have made de-orbiting much more difficult and dangerous. With some controversy, NASA decided in the interest of public safety that a controlled crash was preferable to letting the craft come down at random.

In 2001, the Russian ''[[Mir]]'' space station was deliberately de-orbited, and broke apart in the fashion expected by the command center during atmospheric reentry. Mir entered the Earth's atmosphere on March 23, 2001, near [[Nadi]], [[Fiji]], and fell into the South Pacific Ocean.

On February 21, 2008, a disabled U.S. [[spy satellite]], [[USA-193]], was hit at an altitude of approximately {{convert|246|km|sp=us}} with an [[SM-3]] missile fired from the U.S. Navy [[cruiser]] {{USS|Lake Erie|CG-70|2}} off the coast of [[Hawaii]]. The satellite was inoperative, having failed to reach its intended orbit when it was launched in 2006. Due to its rapidly deteriorating orbit it was destined for uncontrolled reentry within a month. [[U.S. Department of Defense]] expressed concern that the {{convert|1000|lb|adj=on}} fuel tank containing highly toxic [[hydrazine]] might survive reentry to reach the Earth's surface intact. Several governments including those of Russia, China, and [[Belarus]] protested the action as a thinly-veiled demonstration of US anti-satellite capabilities.<ref>{{cite news |first=Andrew |last=Gray |title= U.S. has high confidence it hit satellite fuel tank |url= https://www.reuters.com/article/scienceNews/idUSN1930844420080222 |work=Reuters |date=2008-02-21 |access-date=2008-02-23| archive-url= https://web.archive.org/web/20080225204300/https://www.reuters.com/article/scienceNews/idUSN1930844420080222| archive-date= 25 February 2008 | url-status= live}}</ref> China had previously caused an international incident when it [[2007 Chinese anti-satellite missile test|tested an anti-satellite missile]] in 2007.

<gallery>
File:Closeup of Gemini 2 heatshield.jpg|Closeup of [[Gemini 2]] heat shield
File:Cross section of Gemini 2 heatshield.jpg|Cross section of Gemini 2 heat shield
</gallery>