View source for Skylab 4

{{Short description|Third crewed mission to Skylab}}
{{Use mdy dates|date=August 2020}}
{{Use American English|date=January 2014}}
{{Infobox spaceflight
 |name                  = Skylab 4
 |image                 = Skylab and Earth Limb - GPN-2000-001055.jpg
 |image_size            = 250px
 |image_caption         = The final view of [[Skylab]], from the departing mission 4 crew<!--, with Earth in the background-->
 |insignia              = Skylab3-Patch.png
 |insignia_caption      = Due to a NASA management error, crewed Skylab mission patches were designed in conflict with the official mission numbering scheme.
 |mission_type          = 
 |operator              = [[NASA]]
 |COSPAR_ID             = 1973-090A
 |SATCAT                = 6936
 |mission_duration      = 84&nbsp;days, 1&nbsp;hour, 15&nbsp;minutes, 30&nbsp;seconds
 |orbits_completed      = 1214
 |distance_travelled    = {{convert|55500000|km|abbr=on|sp=us}}
 |spacecraft            = [[Apollo command and service module|Apollo CSM]]-118
 |manufacturer          = [[Rockwell International|North American Rockwell]]
 |launch_mass           = {{convert|20847|kg|abbr=on}}
 |landing_mass          =
 |launch_date           = {{start-date|November 16, 1973, 14:01:23|timezone=yes}}&nbsp;[[Coordinated Universal Time|UTC]]
 |launch_rocket         = [[Saturn IB]] SA-208
 |launch_site           = [[Kennedy Space Center|Kennedy]] [[Kennedy Space Center Launch Complex 39|LC-39B]]
 |landing_date          = {{end-date|February 8, 1974, 15:16:53|timezone=yes}}&nbsp;UTC
 |landing_site          = {{coord|31|18|N|119|48|W|type:event}}
 |recovery_by           = {{USS|New Orleans|LPH-11|6}}
 |orbit_epoch           = January 21, 1974<ref name=satcat>{{cite web|last=McDowell|first=Jonathan|title=SATCAT|url=http://planet4589.org/space/log/satcat.txt|publisher=Jonathan's Space Pages|access-date=March 23, 2014}}</ref>
 |orbit_reference       = [[geocentric orbit|Geocentric]]
 |orbit_regime          = [[low Earth orbit|Low Earth]]
 |orbit_periapsis       = {{convert|422|km|abbr=on|sp=us}}
 |orbit_apoapsis        = {{convert|437|km|abbr=on|sp=us}}
 |orbit_inclination     = 50.04&nbsp;degrees
 |orbit_period          = 93.11&nbsp;minutes
 |apsis                 = gee
 |docking               = 
 {{Infobox spaceflight/Dock
   |docking_target     = Skylab
   |docking_type       = dock
   |docking_port       = Forward
   |docking_date       = November 16, 1973, 21:55:00&nbsp;UTC
   |undocking_date     = February 8, 1974, 02:33:12&nbsp;UTC
   |time_docked        = 83&nbsp;days, 4&nbsp;hours, 38&nbsp;minutes, 12&nbsp;seconds
 }}
 |crew_size             = 3
 |crew_members          = {{Unbulleted list
  |[[Gerald P. Carr]]
  |[[Edward Gibson|Edward G. Gibson]]
  |[[William R. Pogue]]
}}
 |crew_EVAs             = 4
 |crew_EVA_time         = 
 |crew_photo            = Skylab4 crew.jpg
 |crew_photo_caption    = Left to right: Carr, Gibson and Pogue
 |previous_mission      = [[Skylab 3]]
 |programme             = [[Skylab]] program
}}

'''Skylab 4''' (also '''SL-4''' and '''SLM-3'''<ref name=numbering>{{cite web |url=http://williampogue.com/skylab-numbering-mixup.html |title=Skylab Numbering Fiasco |access-date=February 7, 2009 |year=2007 |work=Living in Space |publisher=William Pogue Official WebSite |archive-url=https://web.archive.org/web/20090202194734/http://williampogue.com/skylab-numbering-mixup.html |url-status=live |archive-date=February 2, 2009}}</ref>) was the third crewed [[Skylab]] mission and placed the third and final [[human spaceflight|crew]] aboard the first American [[space station]].

The mission began on November 16, 1973, with the launch of [[Gerald P. Carr]], [[Edward Gibson]], and [[William R. Pogue]] in an [[Apollo command and service module]] on a [[Saturn IB]] rocket from the [[Kennedy Space Center]], Florida,<ref name=thrkie>{{cite news |url=https://news.google.com/newspapers?id=MDJWAAAAIBAJ&sjid=l-cDAAAAIBAJ&pg=2398%2C3622960 |work=Eugene Register-Guard |location=(Oregon) |agency=Associated Press |title='Three happy rookies' off on longest space voyage |date=November 16, 1973 |page=1A}}</ref> and lasted 84 days, one hour and 16 minutes. A total of 6,051 astronaut-utilization hours were tallied by the Skylab 4 astronauts performing scientific experiments in the areas of medical activities, solar observations, Earth resources, observation of the [[Comet Kohoutek]] and other experiments.

The crewed Skylab missions were officially designated [[Skylab 2]], [[Skylab 3|3]], and 4. Miscommunication about the numbering resulted in the mission emblems reading "Skylab I", "Skylab II", and "Skylab 3" respectively.<ref name=numbering /><ref>{{cite web|url=http://www.collectspace.com/resources/naming_spacecraft.html|title=Naming Spacecraft: Confusion Reigns|last=Pogue|first=William|publisher=collectSPACE|access-date=April 24, 2011}}</ref>

==Launch==
[[File:The Skylab 4 Saturn 1B space vehicle is launched from Pad B, Launch Complex 39.jpg|thumb|The Skylab 4 Saturn 1B space vehicle is launched from Pad B, Launch Complex 39.]]

NASA's launch center was located in an area called [[Cape Kennedy]] since November 28, 1963<!-- May 15, 1964 -->.<ref name=icknwdb>{{cite news |url=https://news.google.com/newspapers?id=U38eAAAAIBAJ&sjid=RMoEAAAAIBAJ&pg=1484%2C5225048 |work=Daytona Beach Morning Journal |location=(Florida) |agency=Associated Press |title=It's Cape Kennedy now |date=November 29, 1963 |page=1}}</ref> Cape Kennedy was restored to its former name of Cape Canaveral officially on October 9, 1973.<ref name=leth>Lethbridge, Clifford J. [http://www.spaceline.org/capehistory/3a.html Spaceline.org "Cape History"]. Spaceline.org. Retrieved on March 23, 2011.</ref><ref name=ckisncc>{{cite news |url=https://news.google.com/newspapers?id=n41OAAAAIBAJ&sjid=fPoDAAAAIBAJ&pg=7245%2C2691579 |work=Lakeland Ledger |location=(Florida) |agency=(Washington Post) |title=Cape Kennedy is now Cape Canaveral |date=October 10, 1973 |page=8A}}</ref> The [[Saturn V]] launch facilities at LC-39A and LC-39B were still located at the [[Kennedy Space Center]] on [[Merritt Island, Florida|Merritt Island]].<ref name=leth/> The Skylab 4 mission was the first crewed launch since the area changed its name back to Cape Canaveral;<ref name=sasetfo>{{cite news |url=https://news.google.com/newspapers?id=Z-MpAAAAIBAJ&pg=3778%2C4892 |work=Daytona Beach Morning Journal |location=(Florida) |title=Skylab astronauts set for 9:01 launch today |date=November 16, 1973 |page=1A}}</ref> it launched from the Kennedy Space Center's LC-39B pad on November 16, 1973.<ref name=sdcthrd>{{cite news |url=https://news.google.com/newspapers?id=36dYAAAAIBAJ&pg=6498%2C5079|work=[[Spokane Daily Chronicle]] |location=(Washington)|agency=Associated Press |title=Third Skylab crew fired aloft |date=November 16, 1973 |page=1}}</ref>

==Crew==
{{Spaceflight crew
|terminology      = Astronaut
|position1        = Commander
|crew1_up         = [[Gerald P. Carr]]
|flights1_up      = Only
|position2        = Science Pilot
|crew2_up         = [[Edward Gibson|Edward G. Gibson]]
|flights2_up      = Only
|position3        = Pilot
|crew3_up         = [[William R. Pogue]]
|flights3_up      = Only
}}

With three rookies, Skylab 4 was the largest all-rookie crew launched by [[NASA]]. Following the all rookie [[Mercury program]], there were only four all-rookie NASA flights – [[Gemini 4]], [[Gemini 7]], [[Gemini 8]], and Skylab 4.

===Backup crew===
{{Spaceflight crew
|terminology      = Astronaut
|position1        = Commander
|crew1_up         = [[Vance Brand|Vance D. Brand]]
|position2        = Science Pilot
|crew2_up         = [[William B. Lenoir|William Lenoir]]
|position3        = Pilot
|crew3_up         = [[Don Lind|Don L. Lind]]
}}

===Support crew===
*[[Robert Crippen|Robert L. Crippen]]
*[[Henry Hartsfield|Henry W. Hartsfield, Jr]]
*[[Bruce McCandless II]]
*[[F. Story Musgrave]]
*[[Russell L. Schweickart]]
*[[William E. Thornton]]
*[[Richard Truly|Richard H. Truly]]

==Mission parameters==
{{Bar graph
| title       = Days in Space
| float       = right
| bar_width   = 10
| width_units = em
| data_max    = 100
| label_type  = Mission
| data_type   = #
| label1      = [[Skylab 2]]
| data1       = 28
| label2      = [[Skylab 3]]
| data2       = 60
| label3      = Skylab 4
| data3       = 84
}}
*'''[[Mass]]:''' {{convert|20847|kg|lb|abbr=on}}
*'''Maximum altitude:''' {{convert|440|km|mi|abbr=on|sigfig=3}} (November 16, 1973)
*'''Total distance traveled:''' 34.5 million miles (55,500,000&nbsp;km)
*'''Launch Vehicle:''' [[Saturn IB]] SA-208
*'''Spacecraft:''' [[Apollo CSM]]-118
*'''[[Epoch (astronomy)|Epoch]]:''' January 21, 1974
*'''[[Perigee]]:''' {{convert|422|km|mi|abbr=on}}
*'''[[Apogee]]:''' {{convert|437|km|mi|abbr=on}}
*'''[[Inclination]]:''' 50.04°
*'''[[Orbital period|Period]]:''' 93.11 min

===Docking===
*'''Docked''': November 16, 1973 – 21:55:00 UTC
*'''Undocked''': February 8, 1974 – 02:33:12 UTC
*'''Time Docked''': 83 days, 4 hours, 38 minutes, 12 seconds

===Space walks===
;''Gibson and Pogue'' – EVA 1
:'''Start''': November 22, 1973, 17:42 UTC
:'''End''': November 23, 00:15 UTC
:'''Duration''': 6 hours, 33 minutes
;''Carr and Pogue'' – EVA 2
:'''Start''': December 25, 1973, 16:00 UTC
:'''End''': December 25, 23:01 UTC
:'''Duration''': 7 hours, 01 minute
;''Carr and Gibson'' – EVA 3
:'''Start''': December 29, 1973, 17:00 UTC
:'''End''': December 29, 20:29 UTC
:'''Duration''': 3 hours, 29 minutes
;''Carr and Gibson'' – EVA 4
:'''Start''': February 3, 1974, 15:19 UTC
:'''End''': February 3, 20:38 UTC
:'''Duration''': 5 hours, 19 minutes

==Mission highlights==
[[File:Sl3-113-1587.jpg|thumb|upright|One of the dummies left behind by the Skylab 3 crew to be found by the Skylab 4 crew]]
[[File:Skylab 4 trash.jpg|thumb|upright|Bill Pogue (left) and Gerald Carr pass trash through an airlock to Skylab's waste disposal tank.]]
[[File:Kohoutek-uv.jpg|thumb|upright|alt=Kohoutek-uv|False color image of Comet Kohoutek photographed with the far-ultraviolet electrographic camera during a Skylab spacewalk on December 25, 1973]]
[[File:Skylab Solar flare.jpg|right|thumb|Solar prominence photographed December 19, 1973, by the [[Apollo Telescope Mount]]]]

The all-rookie astronaut crew arrived aboard Skylab to find three figures dressed in flight suits. Upon closer inspection, they found these were dummies with Skylab 4 mission emblems and name tags which had been left there by [[Al Bean]], [[Jack Lousma]], and [[Owen Garriott]] at the end of [[Skylab 3]].<ref>{{cite web|title = Photo-sl3-113-1587|url = http://spaceflight.nasa.gov/gallery/images/skylab/skylab3/html/sl3-113-1587.html|archive-url = https://web.archive.org/web/20150508042241/http://spaceflight.nasa.gov/gallery/images/skylab/skylab3/html/sl3-113-1587.html|url-status = dead|archive-date = May 8, 2015|website = spaceflight.nasa.gov|access-date = May 21, 2015}}</ref>

Things got off to a bad start after the crew attempted to hide Pogue's early [[space sickness]] from flight surgeons, a fact discovered by mission controllers after downloading onboard voice recordings.  Astronaut office chief [[Alan B. Shepard]] reprimanded them for this omission, saying they "had made a fairly serious error in judgement."<ref>{{Cite news |url=https://www.nytimes.com/1973/11/18/archives/skylab-astronauts-are-reprimanded-in-1st-day-aboard-learned-from.html |title=Skylab Astronauts Are Reprimanded In 1st Day Aboard |last=Wilford |first=John Noble |date=November 18, 1973 |work=The New York Times |access-date=July 11, 2018}}</ref>

The crew had problems adjusting to the same workload level as their predecessors when activating the workshop. The crew's initial task of unloading and stowing the thousands of items needed for their lengthy mission also proved to be overwhelming.<ref>{{Cite news |url=https://www.nytimes.com/1973/11/19/archives/astronauts-try-to-make-up-time-skylab-3-lehind-schedule-as-result.html |title=Astronauts Try to Make Up Time |date=November 19, 1973| agency=Associated Press |work=[[The New York Times]] |access-date=July 11, 2018}}</ref> The schedule for the activation sequence dictated lengthy work periods with a large variety of tasks to be performed, and the crew soon found themselves tired and behind schedule.

Seven days into their mission, a problem developed in the Skylab [[Control moment gyroscope|gyroscopic]] [[Spacecraft attitude control|attitude control]] system, which threatened to bring an early end to the mission. Skylab depended upon three large gyroscopes, sized so that any two of them could provide sufficient control and maneuver Skylab as desired. The third acted as a backup in the event of failure of one of the others.<ref>{{Cite news |url=https://www.nytimes.com/1973/11/24/archives/a-skylab-gyroscope-fails-leaving-only-2-for-control.html |title=A Skylab Gyroscope Fails, Leaving Only 2 for Control |date=November 24, 1973 |work=The New York Times |access-date=July 11, 2018 |agency=Associated Press}}</ref> The gyroscope failure was attributed to insufficient [[lubrication]]. Later in the mission, a second gyroscope showed similar problems,<ref>{{Cite news |url=https://www.nytimes.com/1973/12/08/archives/gyro-on-skylab-is-erratic-officials-are-not-alarmed.html |title=Gyro on Skylab Is Erratic; Officials Are Not Alarmed |date=December 8, 1973 |work=The New York Times |access-date=July 11, 2018 |agency=Associated Press }}</ref><ref>{{Cite news |url=https://www.nytimes.com/1974/01/04/archives/skylab-gyroscope-falters-puzzling-ground-engineers.html |title=Skylab Gyroscope Falters, Puzzling Ground Engineers |date=January 4, 1974 |work=The New York Times |access-date=July 11, 2018 |agency=United Press International}}</ref> but special temperature control and load reduction procedures kept the second one operating, and no further problems occurred.

On [[Thanksgiving (United States)|Thanksgiving Day]], Gibson and Pogue accomplished a 6{{frac|2}} hour spacewalk. The first part of their spacewalk was spent deploying experiments and replacing film in the solar observatory. The remainder of the time was used to repair a malfunctioning antenna.  During the experience, Gibson remarked, "Boy if this isn't the great outdoors!  Inside, you're just looking out through a window.  Here, you're right in it."<ref>{{Cite news |url=https://www.nytimes.com/1973/11/23/archives/2-astronauts-fix-skylab-antenna-space-walk-for-repairs-and.html |title=Two Astronauts fix Skylab Antenna |date=November 23, 1973 |work=The New York Times |access-date=July 11, 2018 |agency=Associated Press }}</ref> The crew reported that the food was good, but slightly bland. The quantity and type of food consumed was rigidly controlled because of their strict diet. Although the crew would have preferred to use more condiments to enhance the taste of the food, and the amount of salt they could use was restricted for medical purposes, by the third mission the NASA kitchen had increased the availability of condiments, and salt and pepper were in liquid solutions (granular salt and pepper brought aboard by the second crew was little more than "air pollution").<ref>Erling, John (2013) [http://www.voicesofoklahoma.com/wp-content/uploads/2013/10/Pogue_Transcript.pdf Interview with William Pogue] {{Webarchive|url=https://web.archive.org/web/20200531033357/http://www.voicesofoklahoma.com/wp-content/uploads/2013/10/Pogue_Transcript.pdf |date=May 31, 2020 }}. Voices of Oklahoma. p. 33.</ref>

On December 13, the crew sighted [[Comet Kohoutek]] and trained the solar observatory and hand-held cameras on it. They gathered spectra on it using the [[Far Ultraviolet Camera/Spectrograph]].<ref>{{cite web|title=SP-404 Skylab's Astronomy and Space Sciences|date=January 1979 |url=https://history.nasa.gov/SP-404/ch4.htm|access-date=May 14, 2013|archive-url=https://web.archive.org/web/20041113100704/https://history.nasa.gov/SP-404/ch4.htm|archive-date=November 13, 2004 |last1=Lundquist |first1=C. A. }}</ref>  They continued to photograph it as it approached the Sun. On December 30, as it swept out from behind the Sun, Carr and Gibson spotted it as they were performing a spacewalk.

As Skylab work progressed, the astronauts complained of being pushed too hard, and ground controllers complained they were not getting enough work done.  NASA determined major contributing factors were a large number of new tasks added shortly before launch with little or no training, and searches for equipment out of place on the station.<ref name="NatGeo74"/><ref>{{Cite news |url=https://www.nytimes.com/1973/12/12/archives/lethargy-of-skylab-3-crew-is-studied.html |title=Lethargy of Skylab 3 Crew Is Studied |work=The New York Times |agency=Reuters |date=December 12, 1973 |access-date=July 11, 2018}}</ref><ref>{{Cite news |url=https://www.nytimes.com/1973/11/25/archives/skylab-crew-takes-day-off-for-rest.html |title=Skylab Crew Takes Day Off for Rest |date=November 25, 1973 |work=The New York Times |access-date=July 11, 2018 |agency=Associated Press}}</ref>  There was a radio conference to air frustrations<ref>{{Cite news |url=https://www.nytimes.com/1973/12/31/archives/astronauts-debate-work-schedules-with-controllers.html |title=Astronauts Debate Work Schedules With Controllers |date=December 31, 1973 |work=The New York Times |access-date=July 11, 2018 |agency=Associated Press }}</ref> which led to the workload schedule being modified, and by the end of their mission the crew had completed more work than originally planned.

Skylab 4 involved several scientific observations. The crew spent many hours studying the Earth. Carr and Pogue alternately crewed controls, operating the sensing devices which measured and photographed selected features on the Earth's surface. Gibson and the other crew made solar observations, recording about 75,000 new telescopic images of the Sun. Images were taken in the [[X-ray]], [[ultraviolet]], and visible portions of the spectrum.<ref name="NatGeo74"/><ref>[https://web.archive.org/web/20090716025431/https://www.jsc.nasa.gov/Bios/htmlbios/gibson-eg.html Edward G. Gibson Biographical Data]. National Aeronautics and Space Administration, Lyndon B. Johnson Space Center</ref>

As the end of their mission drew closer, Gibson continued his watch of the solar surface. On January 21, 1974, an active region on the Sun's surface formed a bright spot which intensified and grew.<ref name="NatGeo74">{{Cite journal |last=Canby |first=Thomas |date=October 1974 |title=Skylab, Outpost on the Frontier of Space |url=https://archive.nationalgeographic.com/?iid=54304#folio=468 |journal=National Geographic Magazine |volume=146 |pages=441–493}}{{rp|468}}</ref> Gibson quickly began filming the sequence as the bright spot erupted. This film was the first recording from space of the birth of a [[solar flare]].

The crew also photographed the Earth from orbit. Despite instructions not to do so, the crew (perhaps inadvertently) photographed [[Area 51]], causing a minor dispute between various government agencies as to whether the photographs showing this secret facility should be released. In the end, the picture was published along with all others in NASA's Skylab image archive, but remained unnoticed for years.<ref>[http://www.thespacereview.com/article/1010/1 Secret Apollo]. ''The Space Review''. November 26, 2007</ref>

The Skylab 4 astronauts completed 1,214 Earth orbits and four EVAs totaling 22 hours, 13 minutes. They traveled 34.5 million miles (55,500,000&nbsp;km) in 84 days, 1 hour and 16 minutes in space. Skylab 4 was the last Skylab mission; the station fell from orbit in 1979.

The three astronauts had joined NASA in the mid-1960s, during the [[Apollo program]], with Pogue and Carr becoming part of the likely crew for the cancelled [[Apollo 19]]. Ultimately none of the crew of Skylab 4 flew in space again, as none of the three were selected for [[Apollo–Soyuz]] and all of them retired from NASA before the first [[Space Shuttle]] launch. Gibson, who had trained as a [[NASA Astronaut Group 4|scientist-astronaut]], resigned from NASA in December 1974 to do research on Skylab solar physics data, as a senior staff scientist with [[The Aerospace Corporation]] of Los Angeles, California.

==Communications break==
An unplanned communications break occurred during the Skylab 4 mission: its crew did not communicate with mission control for the portion of one orbit during which Skylab had line of sight to its tracking stations.<ref>{{cite news|last=Broad|first=William J.|title=On Edge in Outer Space? It Has Happened Before|newspaper=[[The New York Times]]|url=https://www.nytimes.com/1997/07/16/world/on-edge-in-outer-space-it-has-happened-before.html|date=July 16, 1997|accessdate=January 29, 2017}}</ref> Before the midpoint of the mission, the Skylab 4 crew had started to become fatigued and behind on the work. In order to catch up, they decided that only one crew member needed to be present for the daily briefing instead of all three, allowing the other two to complete ongoing tasks.<ref name="bbc gibson"/> At one point, according to both Carr and Gibson, the crew forgot to turn their radios on for the daily briefing, leading to a lack of communications between the crew and ground control during that orbit's period of communications availability. By the next planned period, the crew had reaffirmed radio contact with ground control.<ref name="bbc gibson">{{cite web |url = https://www.bbc.com/news/stories-56346001 |title = Skylab: The myth of the mutiny in space |first= Kirstie |last =Brewer |date = March 20, 2021 |accessdate= March 22, 2021 |publisher = [[BBC]] }}</ref><ref name="carr oral history">{{cite report |url = https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/oral_histories/CarrGP/GPC_10-25-00.pdf |title = Oral History Transcript - Gerald Carr |date = October 25, 2000 |accessdate = March 26, 2021 |first = Kevin |last = Rusnak |publisher = [[NASA Johnson Space Center]] }}</ref> Both Carr and Gibson stated that this event partially contributed to a discussion on December 30, 1973, in which the crew and ground control [[capsule communicator]] [[Richard H. Truly]] revisited the astronauts' schedule in light of their fatigue. Carr called this meeting "the first sensitivity session in space".<ref name="bbc gibson"/><ref name="carr oral history"/> NASA agreed to assign the crew a more relaxed schedule, and productivity for the remaining mission significantly increased, surpassing that of the prior [[Skylab 3]] mission.<ref name="nasa strike"/>

===Consequences===
[[File:HHPS Figure 3-2.jpg|thumb|Performance lapses for time in bed (TIB) over 14 days of sleep restriction<ref name="Van Dongen" />]]

NASA spent time studying the causes and effects of the unintentional lack of communications to avoid its replication in future missions.<ref name=":1" /> At the time, only the crew of Skylab 3 had spent six weeks in space. It was unknown what had happened psychologically. NASA carefully worked with crew's requests, reducing their workload for the next six weeks. The incident took NASA into an unknown realm of concern in the selection of astronauts, still a question as humanity considers human missions to Mars or returning to the Moon.<ref name="AutoFP-4" /> Among the complicating factors was the interplay between management and subordinates. On Skylab 4, one problem was that the crew was pushed even harder as they fell behind on their workload, creating an increasing level of stress.<ref name="AutoFP-5" /> Even though none of the astronauts returned to space, there was only one more NASA spaceflight in the decade and Skylab was the first and last American space station.<ref name="armaghplanet.com" /> NASA was planning larger space stations but its budget shrank considerably after the Moon landings, and the Skylab orbital workshop was the only major execution of [[Apollo Applications Program|Apollo Applications]] projects.<ref name="armaghplanet.com" />

The final Skylab mission became known for the incident, and also known for the large amount of work that was accomplished in the long mission.<ref name=":0" /> Skylab orbited for six more years before its orbit decayed in 1979 due to solar activity that was higher than expected.<ref name=":1" /> The next crewed U.S. spaceflights were the [[Apollo–Soyuz Test Project]] in July 1975, then the first Space Shuttle orbital flight [[STS-1]] in April 1981.

The event, which the involved astronauts have joked about,<ref name="nytimes pogue obit">{{cite news |last=Vitello |first=Paul |title=William Pogue, Astronaut Who Staged a Strike in Space, Dies at 84 |newspaper=The New York Times |url=https://www.nytimes.com/2014/03/11/science/space/william-r-pogue-astronaut-who-flew-longest-skylab-mission-is-dead-at-84.html |date=March 10, 2014 |accessdate=January 30, 2017}}</ref> has been a case study in various fields of endeavor including [[space medicine]], [[Team composition and cohesion in spaceflight missions|team management]], and [[Space psychology|psychology]]. According to ''[[Space Safety Magazine]]'', the incident affected the planning of future space missions, especially long-term missions.<ref name=":0" />

The described events were considered a significant example of "us versus them" syndrome in space medicine.<ref name="Clément" /> Crew psychology has been a point of study for Mars analog missions such as [[Mars-500]], with a particular focus on crew behavior triggering a mission failure or other issues.<ref name="Clément" /> One of the impacts of the incident is the requirement that at least one member of the International Space Station crew be a space veteran (not be on a first flight).<ref name="AutoFP-6" />

The 84-day stay of the Skylab 4 mission was a human spaceflight record that was not exceeded for over two decades by a NASA astronaut.<ref name=":3" /> The 96-day Soviet [[Salyut 6 EO-1]] mission broke Skylab 4's record in 1978.<ref>{{Cite web|url=http://www.globalsecurity.org/space/world/russia/soyuz_26_27_series.htm|title=Soyuz 26 and Soyuz 27|last=Pike|first=John|website= globalsecurity.org|access-date=2017-01-05}}</ref><ref>{{cite web |last1=Hollingham |first1=Richard |title=How the most expensive structure in the world was built |url=https://www.bbc.com/future/article/20151221-how-the-most-expensive-structure-in-the-world-was-built |website=BBC |date=December 21, 2015}}</ref>

===In the media===
{{anchor|Skylab strike}}
The communications failure has been interpreted by the media as a deliberate act<ref name="nasa strike"/><ref name="nytimes pogue obit"/><ref name="Hiltzik" /> and became known as the '''Skylab strike''' or '''Skylab mutiny'''. One of the first accounts reporting that a strike aboard Skylab had occurred was published in ''[[The New Yorker]]'' on August 22, 1976, by [[Henry S. F. Cooper Jr.|Henry S. F. Cooper]], who claimed that the crew were alleged to have stopped working on December 28, 1973.<ref>{{cite news |last=Cooper |first=Henry S. F. |author-link=Henry S. F. Cooper Jr. |title=Life in a Space Station |newspaper=[[The New Yorker]] |url=http://www.newyorker.com/magazine/1976/09/06/life-in-a-space-station-ii|date=August 30, 1976|accessdate=January 30, 2017}}</ref><ref name="nasa strike"/> Cooper also published similar claims in his book ''A House in Space'' that same year.<ref name="nasa strike"/> The [[Harvard Business School]] published a 1980 report, "Strike in Space", also claiming that the astronauts had gone on strike, but without citing any sources.<ref name="nasa strike"/>

NASA, the astronauts involved, and spaceflight historians have stated that no strike occurred. NASA has suggested the events of December 28 may have been confused with a day off that was given to the crew on December 26 following the completion of a long spacewalk by Carr and Pogue the day before.<ref name="bbc gibson"/><ref name="nasa strike">{{cite web |url = https://www.nasa.gov/feature/the-real-story-of-the-skylab-4-strike-in-space/ |title = The Real Story of the Skylab 4 "Strike" in Space |first = John |last= Uri |date = November 16, 2020 |accessdate = March 22, 2021 |publisher = [[NASA]] }}</ref> NASA added that there may also have been confusion with a known ground equipment failure on December 25; this left them unable to track Skylab for one orbit, but the crew were notified of this issue ahead of time.<ref name="nasa strike"/> Both Carr and Gibson have stated that it was a series of misjudgments and not the crew's intent that caused them to miss the briefing.<ref name="bbc gibson"/><ref name="carr oral history"/><ref name="gibson oral history">{{cite web |url =https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/oral_histories/GibsonEG/GibsonEG_12-1-00.htm |title = Oral History Transcript - Edward G. Gibson |first = Carol |last= Butler |date = December 1, 2000 |accessdate = March 26, 2021 |publisher = [[NASA Johnson Space Center]] }}</ref> Spaceflight history author [[David Hitt]] also disputed that the crew deliberately ended contact with mission control, in a book written with former astronauts [[Owen K. Garriott]] and [[Joseph P. Kerwin]].<ref name="HS">{{cite book |last=Hitt |first=David |author-link=David Hitt |title=Homesteading Space: The Skylab Story|publisher=[[University of Nebraska Press]]|url=https://books.google.com/books?id=sR5Cm_zeIekC |date=2008|accessdate=January 29, 2017 |isbn=978-0803219014}}</ref>

==Gallery==
<gallery class="center">
File:S74-17305.jpg|Commander Gerald Carr flies a [[Manned Maneuvering Unit]] prototype.
File:Carr i Pogue..jpg|Carr "balances" Bill Pogue as a demonstration of [[zero-G]].
File:SL4-150-5074.jpg|Ed Gibson floats out of the Multiple Docking Adapter connecting the station to the crew's Command Module.
File:Skylab looking down.jpg|Carr and Gibson look through the length of the station from the trash airlock.
File:SL4-150-5075.jpg|Carr floats with limbs outstretched to show the effects of zero-G.
File:Seiko Automatic-Chronograph Cal. 6139 mit gelbem Zifferblatt, die sogenannte „Pogue Seiko“.jpg|The ''[[Seiko|Pogue Seiko]]'', a 'Seiko Automatic-Chronograph' Cal. 6139, the first automatic chronograph in space, used by Bill Pogue<ref>[http://historical.ha.com/itm/explorers/space-exploration/william-pogue-s-seiko-6139-watch-flown-on-board-the-skylab-4-mission-from-his-personal-collection/a/6007-41138.s William Pogue's Seiko 6139 Watch Flown on Board the Skylab 4 Mission, from his Personal Collection... The First Automatic Chronograph to be Worn in Space.] Heritage Auctions</ref><ref>[http://blog.dreamchrono.com/2013/11/seiko-6139-pogue/ The "Colonel Pogue" Seiko 6139]. dreamchrono.com.</ref>
File:Gibson przy ATM.jpg|Gibson at the controls of the Apollo Telescope Mount
File:S74-15064 Lobus Kohoutek.jpg|Dr. Lubos Kohoutek, discoverer of the Comet Kohoutek, speaks to the Skylab 4 crew via radio-telephone in the Mission Operations Control Room in the Mission Control Center during a visit to JSC.
File:Skylab4 - February 1974 astronaut Edward Gibson.jpg|Gibson during an EVA
</gallery>

==Command Module legacy==
[[File:Skylab 4.tif|thumb|The Skylab 4 command module on display at the National Air and Space Museum]]
[[File:SKYLAB4.jpg|thumb|The Skylab 4 command module as displayed in the Oklahoma History Center in 2024]]

The Skylab 4 command module was transferred to the [[National Air and Space Museum]] in 1975.<ref>[https://airandspace.si.edu/collection-objects/command-module-skylab-4 Skylab 4 Command Module] {{Webarchive|url=https://web.archive.org/web/20180519032308/https://airandspace.si.edu/collection-objects/command-module-skylab-4 |date=May 19, 2018 }}. U.S. National Air and Space Museum. Retrieved on August 5, 2020.</ref> This module is the Command and Service Modules CSM-118 and it spent 84 days in Earth orbit as part of the Skylab mission.<ref name="Command Module, Skylab 4">{{cite web|url=http://www.collectspace.com/news/news-082820a-skylab-4-command-module-oklahoma-exhibit.html|title=Command Module, Skylab 4|website=collectSPACE|access-date=August 28, 2020}}</ref>

The module rolled upside down after splashdown, which happened in about half the Apollo CSM splashdowns; in this situation spheres were inflated on top of the CSM to right the module.<ref>{{cite web|url=https://www.nasa.gov/vision/space/features/upside_down_astronauts.html|title=Upside-Down Astronauts|publisher=NASA |access-date=December 23, 2018}}</ref>

The windows of the Skylab 3 and 4 spacecraft modules were studied for [[micrometeoroid]] impacts.<ref>{{Cite conference|title= Results of the examination of the Skylab/Apollo windows for micrometeoroid impacts. |page=1665|bibcode = 1979LPSC...10.1665C |conference=10th Lunar and Planetary Science Conference |date=March 1979 |last1=Cour-Palais |first1=B. G. |volume=2 |location=Houston, Texas }}</ref>

The module was painted white on half its side to help with [[Spacecraft thermal control|spacecraft thermal management]].<ref name="spaceflightblunders.wordpress.com">{{cite web|url=https://spaceflightblunders.wordpress.com/2017/03/03/making-the-command-modules-heat-shield/|title=Making The Command Module's Heat Shield|date=March 4, 2017|website=Spaceflight Blunders & Greatness|access-date=December 23, 2018}}</ref> Whereas Block II Apollo CSM had [[Kapton]] coated with [[aluminium]] and [[silicon monoxide]], later Skylab modules had white paint for the sunward side.<ref name="spaceflightblunders.wordpress.com"/>

The Skylab 4 Command Module held the record for the longest single spaceflight for an American spacecraft for nearly 50 years until it was broken by [[Crew Dragon Resilience]] flying the [[SpaceX Crew-1]] mission on February 7, 2021. To commemorate the event, the four person crew of Crew-1 spoke live with Edward Gibson from the [[International Space Station]].<ref>{{cite web |url=http://www.collectspace.com/ubb/Forum30/HTML/001501.html |title = US crewed spacecraft flight duration record - collectSPACE: Messages}}</ref>

As of September 2020 the capsule is on display at the [[Oklahoma History Center]].<ref name="Command Module, Skylab 4"/><ref>{{cite web|url= http://www.collectspace.com/news/news-082820a-skylab-4-command-module-oklahoma-exhibit.html |title = Skylab 4 capsule to land in new exhibit at Oklahoma History Center -collectSPACE}}</ref>

==Mission insignia==
The triangular emblem features a large number ''3'' and a rainbow circling three areas of study the astronauts pursued. At the time of the flight, the astronauts issued the following description:

"The symbols in the patch refer to the three major areas of investigation in the mission. The tree represents man's natural environment and refers to the objective of advancing the study of earth resources. The hydrogen atom, as the basic building block of the universe, represents man's exploration of the physical world, his application of knowledge, and his development of technology. Since the sun is composed primarily of hydrogen, the hydrogen symbol also refers to the Solar Physics mission objectives. The human silhouette represents mankind and the human capacity to direct technology with a wisdom tempered by his regard for his natural environment. It also relates to the Skylab medical studies of man himself. The rainbow, adopted from the Biblical story of the Flood, symbolizes the promise that is offered to man. It embraces man and extends to the tree and hydrogen atom, emphasizing man's pivotal role in the conciliation of technology with nature by a humanistic application of our scientific knowledge."

Some versions of the patch included a comet in the top curve because of studies made of the comet Kohoutek.
{{Clear}}

== See also ==
{{Portal|Spaceflight}}
* [[Extra-vehicular activity]]
* [[List of spacewalks]]
* [[Splashdown (spacecraft landing)]]
* [[Timeline of longest spaceflights]]
* [[Psychological and sociological effects of spaceflight]]
* [[Team composition and cohesion in spaceflight missions]]
* [[Effects of sleep deprivation in space]]
{{Clear}}

== References ==
{{reflist|1=30em|refs=
<ref name="Van Dongen">{{cite journal |pmid=12683469 |year=2003 |last1=Van Dongen |first1=HP |last2=Maislin |first2=G |last3=Mullington |first3=JM |last4=Dinges |first4=DF |title=The cumulative cost of additional wakefulness: Dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation |volume=26 |issue=2 |pages=117–26 |journal=Sleep|doi=10.1093/sleep/26.2.117|doi-access=free }}</ref>

<ref name="Hiltzik">{{Cite news|url=http://www.latimes.com/business/hiltzik/la-fi-mh-that-day-three-nasa-astronauts-20151228-column.html|title=The day when three NASA astronauts staged a strike in space|last=Hiltzik|first=Michael|website=[[Los Angeles Times]]|access-date=2017-01-29}}</ref>

<ref name=":0">{{Cite news|url=http://www.spacesafetymagazine.com/space-exploration/skylab/kings-horses-final-mission-skylab-part-3/|title=All the King's Horses: The Final Mission to Skylab (Part 3)|date=2013-12-05|newspaper=Space Safety Magazine|language=en-US|access-date=2017-01-04}}</ref>

<ref name="armaghplanet.com">{{cite web|url=http://www.armaghplanet.com/blog/skylab-everything-you-need-to-know.html|title=Skylab: Everything You Need to Know|website=www.armaghplanet.com|access-date=2017-01-04|archive-date=December 14, 2016|archive-url=https://web.archive.org/web/20161214152234/http://www.armaghplanet.com/blog/skylab-everything-you-need-to-know.html|url-status=dead}}</ref>

<ref name=":1">{{Cite news|url=http://www.space.com/19607-skylab.html|title=Skylab: First U.S. Space Station|newspaper=Space.com|access-date=2017-01-04}}</ref>

<ref name="Clément">{{Cite book|url=https://books.google.com/books?id=Z5VTZGRQvFoC&pg=PA225|title=Fundamentals of Space Medicine|last=Clément|first=Gilles|date=2011-07-15|publisher=Springer Science & Business Media|isbn=978-1-4419-9905-4}}</ref>

<ref name="AutoFP-4">{{Cite news|url=http://www.seeker.com/why-space-madness-fears-haunted-nasas-past-1765739692.html|title=Why 'Space Madness' Fears Haunted NASA's Past|last=DNews|date=2012-04-16|newspaper=Seeker – Science. World. Exploration.|access-date=2017-01-04}}</ref>

<ref name="AutoFP-5">{{Cite news|url=https://www.wired.com/2013/05/skylab-40th-anniversary/|title=Skylab: America's First Home in Space Launched 40 Years Ago Today|author=<!--Staff writer(s); no by-line.-->|newspaper=WIRED|language=en-US|access-date=2017-01-04}}</ref>

<ref name="AutoFP-6">{{cite book|author=Gilles Clément|title=Fundamentals of Space Medicine|url=https://books.google.com/books?id=Z5VTZGRQvFoC&pg=PA225|year=2011|publisher=Springer Science & Business Media|isbn=978-1-4419-9905-4|page=255}}</ref>

<ref name=":3">{{cite web
| url=https://hypertextbook.com/facts/2006/KieshaHarding.shtml
| title=Duration of the longest space flight
| first=Kiesha
| last=Harding
| year=2006
| website=The Physics Factbook
| editor-last=Elert
| editor-first=Glenn
| accessdate=2022-01-24
}}</ref>

}}

== Further reading ==
* Gilles Clement, ''Fundamentals of Space Medicine,'' Microcosm Press, 2003. pp.&nbsp;212.
* Lattimer, Dick (1985). ''All We Did was Fly to the Moon''. Whispering Eagle Press. {{ISBN|0-9611228-0-3}}.

== External links ==
{{commons|Skylab 4}}
{{wikiquote}}
* [https://web.archive.org/web/20060103143522/http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720067844_1972067844.pdf Skylab: Command service module systems handbook, CSM 116 – 119 (PDF) April 1972]
* [https://ntrs.nasa.gov/citations/19740021163 Skylab Saturn 1B flight manual (PDF) September 1972]
* [https://history.nasa.gov/SP-4011/contents.htm NASA Skylab Chronology]
* [https://history.nasa.gov/SP-4011/app2.htm Marshall Space Flight Center Skylab Summary]
* [https://history.nasa.gov/SP-4012/vol3/table2.51.htm Skylab 4 Characteristics SP-4012 NASA HISTORICAL DATA BOOK]
* [https://web.archive.org/web/20060111083032/http://www.thespacereview.com/article/531/1 Astronauts and Area 51: the Skylab Incident]
* [https://history.nasa.gov/SP-400/ch9.htm Skylab, "The Third Manned Period"], NASA History ([https://web.archive.org/web/20000302040519/http://history.nasa.gov/ History.nasa.gov ])
*[https://web.archive.org/web/20130224083415/http://www.voicesofoklahoma.com/william_pogue.html Voices of Oklahoma interview with William Pogue.] First person interview conducted with William Pogue on August 8, 2012. Original audio and transcript archived with [https://web.archive.org/web/20100729022003/http://voicesofoklahoma.com/index.html Voices of Oklahoma oral history project.]

{{Skylab |before=[[Skylab 3]] |after=[[Apollo–Soyuz Test Project|ASTP]]}}
{{Apollo program}}
{{Orbital launches in 1973}}
{{NASA space program}}

[[Category:1973 in spaceflight]]
[[Category:Extravehicular activity]]
[[Category:Human spaceflights]]
[[Category:Skylab program]]
[[Category:Spacecraft launched in 1973]]
[[Category:Spacecraft which reentered in 1974]]
[[Category:Individual spacecraft in the Smithsonian Institution]]
[[Category:Spacecraft launched by Saturn rockets]]
[[Category:Saturn IB]]
[[Category:Successful space missions]]