Editing Skylab (section)

== After departure ==
<!-- [[File:USNS Vanguard.jpg|thumb|left|[[USNS Mission San Fernando|''Vanguard'' (T-AGM-19)]] seen here as a NASA Skylab tracking ship. Note the tracking radar and telemetry antennas.]] -->
[[File:Skylab 4 undocking.jpg|thumb|right|Skylab in February 1974, as Skylab 4 departs]]

After a boost of {{convert|6.8|mi}} by Skylab 4's Apollo CSM before its departure in 1974, Skylab was left in a [[parking orbit]] of {{convert|269|mi}} by {{convert|283|mi}}<ref name=benson361/> that was expected to last until at least the early 1980s, based on estimates of the 11-year [[sunspot cycle]] that began in 1976.<ref name="harvp|Edelson|1979|p=65">{{harvp|Edelson|1979|p=65}}.</ref>{{r|ap19790704}} In 1962, NASA first considered the potential risks of a space station reentry, but decided not to incorporate a [[retrorocket]] system in Skylab due to cost and acceptable risk.<ref>{{harvp|Benson|Compton|1983|pp=127–129}}.</ref>

The spent 49-ton Saturn V [[S-II]] stage which had launched Skylab in 1973 remained in orbit for almost two years, and made a controlled reentry on January 11, 1975.<ref>{{citation |url=https://www.space.com/40098-chinese-space-station-crash-like-nasa-skylab.html|title=Chinese Space Station May Crash Like NASA's Skylab|date=March 27, 2018}}</ref> The second stage's reentry was mistimed however and deorbited slightly earlier in the orbit than planned.<ref>{{cite news |url=http://archives.chicagotribune.com/1975/01/11/page/6/article/skylab-rocket-debris-falls-in-indian-ocean|title=Skylab Rocket Debris Falls in Indian Ocean|date=January 11, 1975|publisher=Chicago Tribune |page=6|access-date= October 22, 2014}}</ref>

=== Solar activity ===
[[File:Skylab Solar flare.jpg|left|thumb|Skylab captured this view of the Sun]]
[[File:False Color Isophote of a Solar Eruption.jpg|thumb|right|Solar prominence recorded by Skylab on August 21, 1973<ref>{{cite web |url=http://mix.msfc.nasa.gov/abstracts.php?p=1375|archive-url=https://web.archive.org/web/20131112194856/http://mix.msfc.nasa.gov/abstracts.php?p=1375|url-status=dead|archive-date=2013-11-12|title=A Solar Prominence Taken by the Skylab Telescope}} {{PD-notice}}</ref>]]

British mathematician [[Desmond King-Hele]] of the [[Royal Aircraft Establishment]] (RAE) predicted in 1973 that Skylab would de-orbit and crash to Earth in 1979, sooner than NASA's forecast, because of increased [[solar cycle|solar activity]].<ref name="ap19790704">{{cite news |url=https://news.google.com/newspapers?nid=1876&dat=19790704&id=Bj8sAAAAIBAJ&pg=5468,1065536|title=Foreign Astrologers, Soothsayers Make Skylab Predictions|work=Spartanburg Herald|date=July 4, 1979|agency=Associated Press|page=B8|access-date=September 1, 2016}}</ref> Greater-than-expected solar activity<ref>{{harvp|Benson|Compton|1983|p=362}}.</ref> heated the outer layers of Earth's atmosphere and increased drag on Skylab. By late 1977, [[NORAD]] also forecast a reentry in mid-1979;<ref name="harvp|Edelson|1979|p=65"/> a [[National Oceanic and Atmospheric Administration]] (NOAA) scientist criticized NASA for using an inaccurate model for the second most-intense sunspot cycle in a century, and for ignoring NOAA predictions published in 1976.<ref>{{harvp|Benson|Compton|1983|pp=362–363}}.</ref>

The reentry of the USSR's nuclear powered [[Cosmos 954]] in January 1978, and the resulting radioactive debris fall in [[northern Canada]], drew more attention to Skylab's orbit. Although Skylab did not contain radioactive materials, the [[United States Department of State|State Department]] warned NASA about the potential diplomatic repercussions of station debris.<ref>{{harvp|Benson|Compton|1983|p=363}}.</ref> [[Battelle Memorial Institute]] forecast that up to 25 tons of metal debris could land in 500 pieces over an area {{convert|4000|mi}} long and {{convert|1000|mi}} wide. The lead-lined film vault, for example, might land intact at {{convert|400|ft/s|m/s}}.<ref name="lewis1984">{{cite book |title=The Voyages of Columbia: The First True Spaceship |publisher=Columbia University Press |last=Lewis |first=Richard S. |year=1984 |url=https://books.google.com/books?id=v0cG1SdLkP0C |isbn=0-231-05924-8 |pages=80–82 |via=Google Books}}</ref>

Ground controllers re-established contact with Skylab in March 1978<ref>{{harvp|Edelson|1979|pp=65-66}}.</ref> and recharged its batteries.<ref name="time19790716"/> Although NASA worked on plans to reboost Skylab with the Space Shuttle through 1978 and the [[Teleoperator Retrieval System|TRS]] was almost complete, the agency gave up in December 1978 when it became clear that the shuttle would not be ready in time;<ref name="time19790101">{{cite news |url= http://www.time.com/time/magazine/article/0,9171,916583,00.html|archive-url= https://web.archive.org/web/20101022031830/http://www.time.com/time/magazine/article/0,9171,916583,00.html|url-status= dead|archive-date= October 22, 2010|title=Science: Skylab Will Come Tumbling Down|magazine=Time|date=January 1, 1979|page=72}}</ref><ref>{{harvp|Benson|Compton|1983|pp=363–367}}.</ref> its first flight, [[STS-1]], did not occur until April 1981. Also rejected were proposals to launch the TRS using one or two uncrewed rockets<ref name="oberg199202">{{cite magazine|author-link=James Oberg|last=Oberg|first=James |url=http://www.astronautix.com/s/skylabsuntimelyfate.html|title=Skylab's Untimely Fate|magazine=Air & Space|date=February–March 1992|pages=73–79 |url-status=dead |archiveurl=https://web.archive.org/web/20200807043634/http://www.astronautix.com/s/skylabsuntimelyfate.html|archivedate=2020-08-07}}</ref> or to attempt to destroy the station with missiles.<ref name=lewis1984/>

=== Re-entry and debris ===
{{further|List of reentering space debris}}
[[File:Skylab reentry map.svg|thumb|[[Equirectangular projection]] relief map of the Skylab [[Atmospheric entry|re-entry]] site and final orbits, as predicted by [[NASA]]]]
[[File:Skylab O2 Tank Fragment - US Space & Rocket Center - Alabama - USA.jpg|thumb|right|Fragment of Skylab recovered after its re-entry through [[Atmosphere of Earth|Earth's atmosphere]], on display at the [[U.S. Space & Rocket Center]]]]

Skylab's impending demise in 1979 was an international media event,<ref>{{cite news |last=Shales |first=Tom |author-link=Tom Shales |title=Please, Mr. Skylab: The Greatest Hits on Earth |url=https://www.washingtonpost.com/archive/lifestyle/1979/07/10/please-mr-skylab-the-greatest-hits-on-earth/7fd747aa-e503-43e4-aa12-d402c688fb40/ |newspaper=The Washington Post |date=July 10, 1979}}</ref> with T-shirts and hats with bullseyes<ref name=lewis1984/> and "Skylab Repellent" with a money-back guarantee,{{r|carrier19790708}} wagering on the time and place of re-entry, and nightly news reports. The ''[[San Francisco Examiner]]'' offered a US$10,000 prize (equivalent to ${{Formatprice|{{Inflation|US|10000|1979|r=-3}}}} today){{Inflation-fn|US}} for the first piece of Skylab delivered to its offices; the rival ''[[San Francisco Chronicle]]'' offered US$200,000 (${{Formatprice|{{Inflation|US|200000|1979|r=-3}}}} today){{Inflation-fn|US}} if a subscriber suffered personal or property damage.<ref name="time19790716"/> A Nebraska neighborhood painted a target so that the station would have "something to aim for", a resident said.<ref name="carrier19790708">{{cite news |url=https://www.newspapers.com/clip/6466603//|title=Some find Skylab good for 'Skylaughs'|publisher=The Kokomo Tribune|date=July 8, 1979|agency=Associated Press|access-date=September 1, 2016|author=Carrier, Jim|pages=37}}</ref>

The ''Examiner'' created the prize to compete with the ''Chronicle'' and its popular columnist [[Herb Caen]]. Publisher [[Reg Murphy]] was reluctant to pay the money, [[Jeff Jarvis]] recalled, but NASA assured Jarvis—Caen's counterpart at the ''Examiner''—that the station would not hit land.<ref name="chamings20230504">{{Cite news |last=Chamings |first=Andrew |date=2023-05-04 |title=A space station fell to Earth. An Australian boy brought it to San Francisco |language=en |work=SFGATE |url=https://www.sfgate.com/sfhistory/article/the-skylab-race-to-san-francisco-18074888.php |access-date=2023-11-20}}</ref> A report commissioned by NASA calculated that the odds were 1 in 152 of debris hitting any human, and odds of 1 in 7 of debris hitting a city of 100,000 people or more.<ref>{{cite news|first=James|last=Coates |url= https://news.google.com/newspapers?nid=1291&dat=19790701&id=h9gPAAAAIBAJ&pg=6094,67904&hl=en|title=Skylab Danger Isn't as Small as NASA Hints|publisher=Boca Raton News|page=7|date=July 1, 1979|via=Google News}}</ref> Special teams were readied to head to any country hit by debris.<ref name="time19790716">{{cite news |url=http://www.time.com/time/printout/0,8816,920502,00.html|archive-url=https://web.archive.org/web/20070213023709/http://www.time.com/time/printout/0,8816,920502,00.html|url-status=dead|archive-date=February 13, 2007|title=Skylab's Fiery Fall|publisher=Time|date=July 16, 1979|page=20}}</ref> The event caused so much panic in the [[Philippines]] that President [[Ferdinand Marcos]] appeared on national television to reassure the public.{{r|ap19790704}}

A week before re-entry, NASA forecast that it would occur between July 10 and 14, with the 12th the most likely date, and the [[Royal Aircraft Establishment]] (RAE) predicted the 14th.{{r|ap19790704}} In the hours before the event, ground controllers adjusted Skylab's orientation to minimize the risk of re-entry on a populated area.<ref name="time19790716"/> They aimed the station at a spot {{convert|810|mi}} south-southeast of [[Cape Town]], South Africa, and re-entry began at approximately 16:37 UTC, July 11, 1979.<ref name="benson371">{{harvp|Benson|Compton|1983|p=371}}.</ref> The station did not burn up as fast as NASA expected. Debris landed about {{convert|300|mi}} east of [[Perth]], Western Australia due to a four-percent calculation error,<ref name=benson371/> and was found between [[Esperance, Western Australia]] and [[Rawlinna]], from 31° to 34° S and 122° to 126° E, about 130–150&nbsp;km (81–93 miles) radius around [[Balladonia, Western Australia]]. Residents and an airline pilot saw dozens of colorful flares as large pieces broke up in the atmosphere;<ref name= lewis1984/> the debris landed in an almost unpopulated area, but the sightings still caused NASA to fear human injury or property damage. Don Lind, in a 2005 interview, reports no human injuries or deaths.<ref name="lindoh"/>

Stan Thornton found 24 pieces of Skylab at his home in Esperance. After obtaining his first passport, Thornton flew to [[San Francisco]]. After waiting one week for Marshall Space Flight Center to authenticate the wreckage, he collected the ''Examiner'' prize and another US$1,000 from a Philadelphia businessman who had flown Thornton's family and girlfriend there.{{r|chamings20230504}}<ref name=benson371/><ref name=lewis1984/> Analysis of the debris showed that the station had disintegrated {{convert|10|mi}} above the Earth, much lower than expected.<ref name=lewis1984/>

The [[Shire of Esperance]] light-heartedly fined NASA A$400 for [[litter]]ing,<ref>{{cite web |last=O'Neill |first=Ian |date=July 14, 2009 |title=Celebrating July 13, "Skylab-Esperance Day" |url=http://www.seeker.com/celebrating-july-13-skylab-esperance-day-1764710421.html |url-status=deviated |archive-url=https://web.archive.org/web/20230720074217/https://www.seeker.com/celebrating-july-13-skylab-esperance-day-1764710421.html |archive-date=July 20, 2023 |access-date=July 27, 2019 |website=seeker.com |publisher=Group Nine Media, Inc.}}</ref> and while the fine was indeed [[written off]] three months later, it was nonetheless eventually paid on behalf of NASA in April 2009, after Scott Barley of Highway Radio raised the funds from his morning show listeners.<ref>{{cite news|first=Hannah|last=Siemer |url=http://esperance.yourguide.com.au/news/local/news/general/littering-fine-paid/1488319.aspx?storypage=1 |title=Littering Fine Paid|publisher=The Esperance Express|date= April 17, 2009 |url-status=dead|archive-url=https://archive.today/20120711163508/http://esperance.yourguide.com.au/news/local/news/general/littering-fine-paid/1488319.aspx?storypage=1|archive-date=July 11, 2012}}</ref><ref>{{cite news |last=Sutherland |first=Paul |date=July 5, 2009 |title=NASA's Litter Bill Paid 30 Years On |url=http://www.skymania.com/wp/2009/07/nasas-litter-bill-paid-30-years-on.html/691/ |archive-url=https://web.archive.org/web/20230720074217/http://www.seeker.com/celebrating-july-13-skylab-esperance-day-1764710421.html |archive-date=July 20, 2023 |publisher=Skymania News}}</ref>

After the demise of Skylab, NASA focused on the reusable [[Spacelab]] module, an orbital workshop that could be deployed with the Space Shuttle and returned to Earth. The next American major space station project was [[Space Station Freedom]], which was merged into the International Space Station in 1993 and launched starting in 1998. [[Shuttle-Mir]] was another project and led to the US funding [[Spektr]], [[Priroda]], and the [[Mir Docking Module]] in the 1990s.