Editing Skylab 2

{{short description|First crewed mission to Skylab}}
{{about|the first crewed mission to Skylab|the backup Skylab space station|Skylab B|the NASA L2 space station concept|Skylab II|other uses|Skylab Two (disambiguation){{!}}Skylab Two}}
{{Use mdy dates|date=April 2012}}
{{Infobox spaceflight
| name               = Skylab 2
| image              = 40 Years Ago, Skylab Paved Way for International Space Station.jpg
| image_caption      = Skylab, seen from the departing Skylab 2 spacecraft
| insignia           = Skylab1-Patch.png
| insignia_caption   = Mission patch. Due to a NASA management error, crewed Skylab mission patches were designed in conflict with the official mission numbering scheme.
| mission_type       = Crewed mission to [[Skylab]]
| operator           = [[NASA]]
| mission_duration   = 28&nbsp;days, 49&nbsp;minutes, 49&nbsp;seconds
| orbits_completed   = 404
| distance_travelled = {{cvt|18500000|km|mi nmi}}
| spacecraft         = [[Apollo Command/Service Module|Apollo CSM]]-116
| manufacturer       = [[Rockwell International|North American Rockwell]]
| launch_mass        = {{cvt|19979|kg}}
| launch_date        = {{End date|1973|05|25|13|00|00|Z}}
| launch_rocket      = [[Saturn IB]] SA-206
| launch_site        = [[Kennedy Space Center|Kennedy]], [[Kennedy Space Center Launch Complex 39|LC-39B]]
| landing_date       = {{End date|1973|06|22|13|49|48|Z}}
| landing_site       = {{coord|24|45|N|127|2|W|type:event}}
| recovery_by        = {{USS|Ticonderoga|CV-14|6}}
| orbit_epoch        = June 4, 1973<ref name="satcat">{{Cite web |last=McDowell |first=Jonathan |title=SATCAT |url=http://planet4589.org/space/log/satcat.txt |access-date=March 23, 2014 |publisher=Jonathan's Space Pages}}</ref>
| orbit_reference    = [[Geocentric orbit]]
| orbit_regime       = [[Low Earth orbit]]
| orbit_periapsis    = {{cvt|428|km|mi nmi}}
| orbit_apoapsis     = {{cvt|438|km|mi nmi}}
| orbit_inclination  = 50°
| orbit_period       = 93.2&nbsp;minutes
| apsis              = gee
| docking            = {{Infobox spaceflight/Dock
   | docking_target     = [[Skylab]]
   | docking_type       = dock
   | docking_port       = Forward
   | docking_date       = May 26, 1973, 09:56&nbsp;UTC
   | undocking_date     = May 26, 1973, 10:45&nbsp;UTC
   | time_docked        = 49&nbsp;minutes<ref name="chronMay26">{{Cite book |url=https://history.nasa.gov/SP-4011/part3c.htm |title=Skylab: A Chronology |publisher=NASA |chapter=PART III: Skylab Development and Operations: February 1970-November 1974 (continued) |access-date=March 26, 2023}}</ref>
 }}
 {{Infobox spaceflight/Dock
   | docking_target     = Skylab
   | docking_type       = dock
   | docking_port       = Forward
   | docking_date       = May 26, 1973, 15:50&nbsp;UTC<ref name="chronMay26" />
   | undocking_date     = June 22, 1973, 08:58&nbsp;UTC<ref name="Gatland">{{Cite book |last=Gatland |first=Kenneth |title=Manned Spacecraft |publisher=MacMillan |year=1976 |isbn=0-02-542820-9 |edition=Second |location=New York |page=223}}</ref>
   | time_docked        = 26&nbsp;days, 11&nbsp;hours, 2&nbsp;minutes
 }}
| crew_size          = 3
| crew_members       = {{Unbulleted list
  |[[Pete Conrad]]
  |[[Joseph P. Kerwin]]
  |[[Paul J. Weitz]]
}}
| crew_EVAs          = 3
| crew_EVA_duration  = 5&nbsp;hours, 41&nbsp;minutes
| crew_photo         = Skylab 2 crew.jpg
| crew_photo_caption = From left: [[Joseph P. Kerwin|Kerwin]], [[Pete Conrad|Conrad]] and [[Paul J. Weitz|Weitz]]
| programme          = [[Skylab]] program
| previous_mission   = [[Skylab#Completion and launch|Skylab 1]]
| next_mission       = [[Skylab 3]]
}}

'''Skylab 2''' (also '''SL-2''' and '''SLM-1'''<ref name="Skylab Numbering Fiasco">{{Cite web |year=2007 |title=Skylab Numbering Fiasco |url=http://williampogue.com/skylab-numbering-mixup.html |url-status=dead |archive-url=https://web.archive.org/web/20090202194734/http://williampogue.com/skylab-numbering-mixup.html |archive-date=February 2, 2009 |access-date=February 7, 2009 |website=Living in Space |publisher=William Pogue Official WebSite |df=mdy-all}}</ref>) was the first [[human spaceflight|crewed]] mission to [[Skylab]], the first American orbital [[space station]]. The mission was launched on an [[Apollo command and service module]] by a [[Saturn IB]] rocket on May 25, 1973,<ref>{{Cite web |title=Skylab 2 (1973) |url=https://texasarchive.org/2015_01854 |access-date=November 29, 2019 |website=Texas Archive of the Moving Image}}</ref> and carried NASA astronauts [[Pete Conrad]], [[Joseph P. Kerwin]], [[Paul J. Weitz]] to the station. The name Skylab 2 also refers to the vehicle used for that mission. The Skylab 2 mission established a twenty-eight-day record for human spaceflight duration. Its crew was the first space station occupants ever to return safely to Earth – the only previous space station occupants, the crew of the 1971 [[Soyuz 11]] mission that had crewed the [[Salyut 1]] station for twenty-four days, died upon reentry due to unexpected cabin [[depressurization]].

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

==Crew==
{{Spaceflight crew
|terminology      = Astronaut
|position1        = Commander
|crew1_up         = [[Pete Conrad|Charles "Pete" Conrad, Jr.]]
|flights1_up      = Fourth and last
|position2        = Science Pilot
|crew2_up         = [[Joseph P. Kerwin]]
|flights2_up      = Only
|position3        = Pilot
|crew3_up         = [[Paul J. Weitz]]
|flights3_up      = First
|notes=Kerwin became the first medical doctor in space. NASA chose a doctor as the first Skylab scientist to better understand the [[effect of spaceflight on the human body]] during a long-duration mission.<ref name="evans2011">{{Cite book |last=Evans |first=Ben |url=https://books.google.com/books?id=IWht0brbIfEC&pg=PA136 |title=At Home in Space : The Late Seventies into the Eighties |publisher=Springer |year=2011 |isbn=978-1-4419-8810-2 |location=New York |pages=136–139, 142 |oclc=756509282}}</ref>}}

===Backup crew===
{{Spaceflight crew
|terminology      = Astronaut
|position1        = Commander
|crew1_up         = [[Rusty Schweickart|Russell L. Schweickart]]
|position2        = Science Pilot
|crew2_up         = [[Story Musgrave|F. Story Musgrave]]
|position3        = Pilot
|crew3_up         = [[Bruce McCandless II]]
}}

===Support crew===
*[[Robert Crippen|Robert L. Crippen]]
*[[Henry Hartsfield|Henry W. Hartsfield, Jr]]
*[[William E. Thornton]]
*[[Richard H. Truly]]

==Mission parameters==
{{div col|colwidth=25em}}
*'''Mass:''' 19,979&nbsp;kg  <!--- of Apollo CSM ? -->
*'''Maximum altitude:''' 440&nbsp;km
*'''Distance:'''  18,536,730.9&nbsp;km
*'''Launch vehicle:''' [[Saturn IB]] SA-206
*'''Spacecraft:''' [[Apollo Command/Service Module|Apollo CSM]]-116
*'''[[Perigee]]:''' 428&nbsp;km
*'''[[Apogee]]:''' 438&nbsp;km
*'''[[Inclination]]:''' 50°
*'''[[Orbital period|Period]]:''' 93.2 min
*'''Soft dock''': May 26, 1973 – 09:56 UTC
*'''Undocked''': May 26, 1973 – 10:45 UTC
*'''Time docked''': 49 minutes
*'''Hard dock''': May 26, 1973 – 15:50 UTC
*'''Undocked''': June 22, 1973 – 08:58 UTC
*'''Time docked''': 26 days, 17 hours, 2 minutes

===Space walks===
;''Weitz'' — EVA 1 (stand up EVA — CM side hatch)
:'''Start''': May 26, 1973, 00:40 UTC
:'''End''': May 26, 01:20 UTC
:'''Duration''': 40 minutes
;''Conrad and Kerwin'' — EVA 2
:'''Start''': June 7, 1973, 15:15 UTC
:'''End''': June 7, 18:40 UTC
:'''Duration''': 3 hours, 25 minutes
;''Conrad and Weitz'' — EVA 3
:'''Start''': June 19, 1973, 10:55 UTC
:'''End''': June 19, 12:31 UTC
:'''Duration''': 1 hour, 36 minutes
{{div col end}}

==Mission highlights==
[[File:Skylab 2 Crew Members.jpg|thumb|left|upright|Paul J. Weitz, (left) Charles Conrad Jr. (middle); and Joseph P. Kerwin (right); in front of Skylab station on its Saturn V]]
[[File:Skylab Station Viewed by Skylab 2 Command Module - GPN-2000-001709.jpg|thumb|View during a "fly around" inspection]]
{{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
}}
The [[Skylab]] station suffered significant damage on its May 14 launch: its micrometeorite shield, and one of its primary [[Photovoltaic module|solar array]]s had torn loose during launch, and the remaining primary solar array was jammed. Without the shield which was designed to also provide thermal protection, Skylab baked in the Sun, and rising temperatures inside the workshop released toxic materials into the station's atmosphere and endangered on-board film and food. The first crew was supposed to launch on May 15, but instead had to train practicing repair techniques as they were developed by the engineers.<ref name="livingandworking">{{Cite journal |last=Compton |first=W. D. |last2=Benson |first2=C. D. |date=1983-01-01 |title=Living and working in space. A history of Skylab |url=https://ntrs.nasa.gov/api/citations/19840017669/downloads/19840017669.pdf |journal=Scientific and Technical Information Branch |publisher=NASA |access-date=2010-05-22}}</ref>{{Reference page|pages=253–255, 259}} Ground controllers purged the atmosphere with pure nitrogen four times, before refilling it with the nitrogen/oxygen atmosphere for the crew.<ref>''Skylab: A Chronology'', May 14</ref> The secret [[National Reconnaissance Office]] used a [[KH-8 Gambit 3]] to photograph the damaged station.<ref name="day20130520">{{Cite web |last=Day |first=Dwayne |date=2013-05-20 |title=Those magnificent spooks and their spying machine: The spies help rescue Skylab |url=https://www.thespacereview.com/article/2299/1 |access-date=2020-07-10 |website=The Space Review}}</ref>

On May 25, Skylab 2 lifted from LC-39B, the first [[Saturn IB]] launch in almost five years and only the second-ever launch from Pad 39B. Booster performance was nominal except for one momentary glitch that could have threatened the mission – when the Commit signal was sent to the Saturn at ignition, the instrument unit sent a command to switch the launch vehicle from internal to external power. This would have shut down the Saturn's electrical system, but not the propulsion system, and likely cause the disaster scenario of an uncontrollable booster, requiring the Launch Escape System to be activated and the Command Module pulled away to safety, followed by Range Safety destroying the errant launch vehicle. However, the duration of the cutoff signal was less than one second, too short a time for the electrical relay in the booster to be activated, so nothing happened and the launch proceeded as planned. This glitch was traced to a modification of the pad electrical equipment and corrective steps were taken to prevent it from happening again.<ref name="livingandworking" />{{Reference page|page=269}}<ref>{{Cite report |url=https://ntrs.nasa.gov/api/citations/19730025087/downloads/19730025087.pdf |title=Saturn 1B launch vehicle flight evaluation report, SA-206, Skylab-2 |date=July 23, 1973 |publisher=NASA |access-date=May 5, 2015}}</ref> On reaching the station, Conrad flew their [[Apollo command and service module|Apollo Command and Service Module]] (CSM) around it to inspect the damage, then soft-docked with it to avoid the necessity of [[orbital station-keeping|station keeping]] while the crew ate, and flight controllers planned the first repair attempt. Then they undocked so that Conrad could position the CSM by the jammed solar panel, and Weitz could perform a stand-up [[Extravehicular activity|EVA]], trying to free the array by tugging at it with a 10-foot hooked pole, while Kerwin held onto his legs. This failed, and consumed a significant amount of the Skylab's nitrogen maneuvering fuel to keep it steady in the process.

The crew then attempted to perform the hard dock to Skylab, but the capture latches failed to operate. After eight failed attempts, they donned their pressure suits again and partially dis-assembled the CSM's docking probe; the next attempt worked. Once inside the station, the crew deployed a collapsible parasol through the small scientific airlock to act as a sunshade. (This approach was suggested and designed by NASA's "Mr. Fix It" [[Jack Kinzler]], who was awarded the [[NASA Distinguished Service Medal]] for the effort.)  Successful deployment of the sunshade dropped inside temperatures to sustainable levels.<ref name="SP400ch4">{{Cite web |last=<!--Staff writer(s); no by-line.--> |year=1977 |title=SP-400 Skylab, Our First Space Station |url=https://history.nasa.gov/SP-400/ch4.htm |access-date=May 8, 2013 |publisher=[[NASA]]}}</ref>

[[File:Skylab 2 Deorbiting.jpg|thumb|View of Skylab from the Skylab 2 Command/Service Module during the final flyaround inspection]]
Two weeks later, Conrad and Kerwin performed a second EVA, freeing the stuck solar panel and increasing the electrical power to the workshop. They had prepared for this repair by [[Neutral buoyancy simulation as a training aid|practicing]] in the [[Neutral Buoyancy Simulator]] at the [[Marshall Space Flight Center]]. Without power from the panel, the second and third Skylab missions would have been unable to perform their main experiments, and the station's critical battery system would have been seriously degraded.<ref name="livingandworking" />{{Reference page|pages=271–276}} During this EVA, the sudden deployment of the solar panel structure caused both astronauts to be flung from the station's hull, testing their nerves as well as the strength of their safety tethers. After recovering their composure, both astronauts returned to their positions on the station and completed the EVA.<ref>David J. Shayler, [[British Interplanetary Society|FBIS]], ''Walking in Space'', 2004, p. 213, Praxis Publishing Ltd.</ref>

For nearly a month they made further repairs to the workshop, conducted medical experiments, gathered solar and Earth science data, and performed a total of 392 hours of experiments. The mission tracked two minutes of a large [[solar flare]] with the [[Apollo Telescope Mount]]; they took and returned some 29,000 frames of film of the sun.<ref name="livingandworking" />{{Reference page|page=291}} The Skylab 2 astronauts spent 28 days in space, which doubled the previous U.S. record. The mission ended successfully on June 22, 1973, when Skylab 2  [[Splashdown (spacecraft landing)|splashing down]] in the Pacific Ocean 9.6&nbsp;km from the recovery ship [[USS Ticonderoga (CV-14)|USS ''Ticonderoga'']]. Skylab 2 set the records for the longest duration crewed spaceflight, greatest distance traveled and greatest mass docked in space. Conrad set the record for most time in space for an astronaut.

==Mission insignia==
The mission patch was designed by [[Frank Kelly Freas|Kelly Freas]], a well-known artist highly regarded in the science fiction community, who was suggested to NASA by science fiction author and editor [[Ben Bova]]. The insignia features Skylab above the earth with the sun in the background. In an article for ''[[Analog Science Fiction/Science Fact]]'' magazine, Freas said, "Among the suggestions the astronauts had made was the idea of a solar eclipse as seen from Skylab. It soon became clear that this idea would solve several problems at once: it pointed up the solar study function of Skylab, it would give me the large circular shape of the Earth as counterpoint to the angularity of the cluster, and it would establish firmly the connection of Skylab to the Earth. In addition, it would give a chance to get the necessary high contrast for good visibility of the tiny finished patch. ... I made several studies of cloud patterns on the planet, reducing them finally to very conventionalized swirls. The Skylab cluster was simplified and simplified again, till it became simply a black form with a white edgelight to set it off."

==Gallery==
<gallery>
Image:Skylab 2,Kerwin in OWS.jpg|Kerwin blows water droplets from a straw.
Image:Skylab 2 - Weitz assists Kerwin with blood pressure cuff.jpg|Weitz assists Kerwin with a [[Sphygmomanometer|blood pressure cuff]].
</gallery>

==Spacecraft location==
The Skylab 2 command module is displayed at the [[National Museum of Naval Aviation]], [[Pensacola, Florida]]. Different for earlier Apollo modules, Skylab ones had white paint on the sunward side to help with [[Spacecraft thermal control|spacecraft thermal management]].<ref name="spaceflightblunders.wordpress.com">{{cite web |date=March 4, 2017 |title=Making The Command Module's Heat Shield |url=https://spaceflightblunders.wordpress.com/2017/03/03/making-the-command-modules-heat-shield/ |access-date=December 23, 2018 |website=Spaceflight Blunders & Greatness}}</ref>
<gallery>
Image:Skylab2-1.jpg|Skylab 2 CM
Image:Skylab2-2.jpg|Skylab 2 CM
Image:Skylab2-3.jpg|Skylab 2 CM interior
</gallery>

==See also==
* [[Extra-vehicular activity]]
* [[List of spacewalks]]
*[[Timeline of longest spaceflights]]

==References==
{{Reflist}}

==External links==
{{Commons}}
* [https://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/archive/nasa/casi.ntrs.nasa.gov/19740021163_1974021163.pdf 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/table2.49.htm Skylab 2 Characteristics SP-4012 NASA HISTORICAL DATA BOOK]
* [http://genedorr.com/patches/Patchwork.html Analog interview with Frank Kelly Freas]

===Multimedia===
{{Commons category-inline|bullet=none|Skylab 2}}
* [https://web.archive.org/web/20110711015438/http://www.footagevault.com/search_results?q=SL-2&f=hd Onboard flight film from the Skylab 2 mission]

{{Skylab | before= [[Skylab 1]]| after=[[Skylab 3]]}}
{{Apollo program}}
{{Orbital launches in 1973}}
{{NASA space program}}
{{Portal bar|Spaceflight}}

{{Use American English|date=January 2014}}

[[Category:1973 in spaceflight]]
[[Category:Extravehicular activity]]
[[Category:Human spaceflights]]
[[Category:Skylab program]]
[[Category:Spacecraft launched in 1973]]
[[Category:Spacecraft which reentered in 1973]]
[[Category:Spacecraft launched by Saturn rockets]]
[[Category:Pete Conrad]]
[[Category:Saturn IB]]
[[Category:Successful space missions]]