The final view of Skylab, from the departing mission 4 crew, with Earth in the background
|Mission duration||84 days, 1 hour, 15 minutes, 30 seconds|
|Distance travelled||55,500,000 kilometers (34,500,000 mi)|
|Manufacturer||North American Rockwell|
|Launch mass||20,847 kilograms (45,960 lb)|
|Start of mission|
|Launch date||November 16, 1973, 14:01:23UTC|
|Rocket||Saturn IB SA-208|
|Launch site||Kennedy LC-39B|
|End of mission|
|Recovered by||USS New Orleans|
|Landing date||February 8, 1974, 15:16:53UTC|
|Perigee altitude||422 kilometers (262 mi)|
|Apogee altitude||437 kilometers (272 mi)|
|Epoch||January 21, 1974|
|Docking with Skylab|
|Docking date||November 16, 1973, 21:55:00 UTC|
|Undocking date||February 8, 1974, 02:33:12 UTC|
|Time docked||83 days, 4 hours, 38 minutes, 12 seconds|
Due to a NASA management error, crewed Skylab mission patches were designed in conflict with the official mission numbering scheme.
Left to right: Carr, Gibson and Pogue
The mission started on November 16, 1973 with the launch of three astronauts on an Apollo command and service module on a Saturn IB rocket from the Kennedy Space Center, Florida and lasted 84 days, one hour and 16 minutes. A total of 6,051 astronaut-utilization hours were tallied by 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, 3, and 4. Mis-communication about the numbering resulted in the mission emblems reading "Skylab I", "Skylab II", and "Skylab 3" respectively.
Cape Kennedy was named Cape Canaveral officially on October 9, 1973. The name restoration to Cape Canaveral became official on October 9, 1973. The first crewed launch under the name of "Cape Canaveral" was the Skylab 4 mission, on November 16, 1973.
|Commander||Gerald P. Carr|
|Science Pilot||Edward G. Gibson|
|Pilot||William R. Pogue|
With three rookies, Skylab 4 was the largest all-rookie crew launched by NASA. Following the all rookie Mercury program, there were only five more all-rookie NASA flights – Gemini 4, Gemini 7, Gemini 8, Skylab 4 and, in 1981, STS-2 (There is debate about STS-2 being an all-rookie crew. Commander Joe Engle had exceeded 50 miles altitude during the X-15 program. Under Air Force rules at the time, Engle was considered to have flown in space and thus had been awarded Astronaut Wings. Subsequently the international standard of 100 km altitude has taken precedence, which would have meant Engle did not officially fly in space. However, during the time of STS-2, Engle had been considered an Air Force spaceflight veteran, even though he was a NASA rookie).
|Commander||Vance D. Brand|
|Science Pilot||William Lenoir|
|Pilot||Don L. Lind|
Gibson and Pogue — EVA 1
Carr and Pogue — EVA 2
Carr and Gibson — EVA 3
Carr and Gibson — EVA 4
The all-rookie astronaut crew arrived aboard Skylab to find that they had company – three figures dressed in flight suits. Upon closer inspection, they found their companions were three dummies, complete 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.
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."
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. 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 gyroscopic 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. The gyroscope failure was attributed to insufficient lubrication. Later in the mission, a second gyroscope showed similar problems, but special temperature control and load reduction procedures kept the second one operating, and no further problems occurred.
On Thanksgiving Day, Gibson and Pogue accomplished a 61⁄2 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." 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 was in liquid solutions (granular salt and pepper brought aboard by the second crew was little more than "air pollution").
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. 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. There was a radio conference to air frustrations which led to the workload schedule being modified, and by the end of their mission the crew had completed even more work than originally planned.
Skylab 4 was noted for several important scientific contributions. 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.
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. 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.
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 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 had been selected for Apollo-Soyuz and all of them retired from NASA before the first Space Shuttle launch. Gibson, who had trained as a 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.
On December 28, 1973, NASA Mission Control in Houston, Texas, could not communicate with Skylab 4 for about 90 minutes, about one full orbit of Earth, when there should have been radio contact. Some claim this was a "strike" and that they turned off all communication with ground control, as they felt over-worked and had discontentment. Others dismiss these claims. Gibson later reported "simply failed to synchronize their radio response shifts, and that as a result, "one day we made a mistake and for a whole orbit we all had our radios off!"  To date, no evidence of this strike announcement has been located in mission transcripts or audio recordings of the flight. According to The New Yorker, the crew were alleged to have stopped working. The exact nature of what happened, or whether anything happened at all, is controversial. Spaceflight history author David Hitt disputed that the crew purposefully ended contact with mission control in a book written along with former astronauts Owen K. Garriott and Joseph P. Kerwin.
Mission Control planned extra work for the rookie crew, and placed considerable faith in measures to hasten their adaptation to working in space. The crew's days were scheduled at rates near the ending rate of the previous crew. The crew fell behind the aggressive schedule and worked through several planned days off. Other factors likely also contributed to crew frustration. The crew pushed back and got some schedule relief mid-December, then described their rest days as not especially restful near new year. Mission Control created a "shopping list" of tasks that could be worked any time, and allowed for a genuine rest day on January 10, and the mission proceeded smoothly afterward.
Though author H.S.F. Cooper, two years after the mission, interpreted events as a "strike" or "rebellion," several modern sources have disputed that characterization. This mission has been raised as case study in various fields of endeavor including space medicine, team management, and psychology. Man-hours in space were, and continued to be into the 21st century, profoundly expensive; a single day on Skylab was worth about $22.4 million in 2017 dollars. Difficulties on this mission also affected the planning of future space missions, especially long-term missions.
Behavioral problems during a spaceflight are of concern to mission planners because they can cause a mission to fail. NASA has studied matters that affect crew social dynamics such as morale, stress management, and how the crew solves problems as a group with missions like HI-SEAS. Each Skylab pushed farther into the unknown of space medicine, and it was difficult to make predictions about the reaction of the human body to prolonged weightlessness. The first crewed Skylab mission set a spaceflight record with its 28-day mission, and Skylab 3 roughly doubled that to 59 days; no one had spent this long in orbit.
Possible contributing factors to the incident include:
Skylab 3 had finished all their work and asked for more work—this may have led NASA to have a higher expectation for the next crew. However, the next crew were all "rookies" (they had not been in space before) and may not have had the same concept of workload as the previous crew. Both previous crews had veteran members and both previous crews had one member that had been to the Moon and back. Another factor was that the rookie astronauts were in denial about their problems and hid the issues they were having with mission control, leading to even higher mental strain. The crew increasingly became bothered by having every hour of their trip duration scheduled.
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.
After the incident, there were many attempts to either determine the cause or downplay what happened. Nevertheless, lessons learned focused on balancing workload with crew psychology and stress level. One factor that affects disaster planning is the process of lessons learned from past incidents. Two contrasting pressures are the desire to hide a problem to avoid issues such as reprimands versus the honest evaluation of the issue to prevent future occurrences.
Among the complicating factors was the interplay between management and subordinates (see also Apollo 1 fire and Challenger disaster). 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. 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. 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 application projects.
Though the final Skylab mission became known for the incident, it was also known for the large amount of work that was accomplished in the long mission. Skylab orbited for six more years before decaying in 1979 due to higher-than-anticipated solar activity. The next U.S. spaceflight was the Apollo–Soyuz Test Project conducted in July 1975, and after a human spaceflight gap, the first Space Shuttle orbital flight STS-1.
The described events were considered a significant example of "us" versus "them" syndrome in space medicine. 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. 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).
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. The 96-day Soviet Salyut 6 EO-1 mission broke Skylab 4's record in 1978.
Commander Gerald Carr flies a Manned Maneuvering Unit prototype.
Carr "balances" Bill Pogue as a demonstration of zero-G.
Ed Gibson floats out of the Multiple Docking Adapter connecting the station to the crew's Command Module.
Carr and Gibson look through the length of the station from the trash airlock.
Carr floats with limbs outstretched to show the effects of zero-G.
Gibson at the controls of the Apollo Telescope Mount.
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.
Gibson during an EVA.
The Skylab 4 command module was transferred to the National Air and Space Museum in 1975. This module is the Command and Service Modules CSM-118 and it spent 84 days in Earth orbit as part of the Skylab mission. As of September 2020 it is on display at the Oklahoma History Center.
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.
The module was painted white on half its side to help with spacecraft thermal management. Whereas Block II Apollo CSM had Kapton coated with aluminium and silicon monoxide, later Skylab modules had white paint for the sunward side.
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.
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.
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