Skylab 4
Skylab 4 was the fourth Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

 mission and placed the third and final crew
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....

 on board the space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...

. The mission started November 16, 1973 with the launch of three astronauts on a Saturn IB
Saturn IB
The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration for use in the Apollo program...

 rocket, and lasted 84 days, 1 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
Comet Kohoutek
Comet Kohoutek, formally designated C/1973 E1, 1973 XII, and 1973f, was first sighted on 7 March 1973 by Czech astronomer Luboš Kohoutek. It attained perihelion on 28 December that same year....

 and other experiments.

The manned 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.


Backup crew

Support crew

  • Robert L. Crippen
    Robert Crippen
    Robert Laurel Crippen is an engineer, retired United States Navy Captain and a former NASA astronaut. He flew on four Space Shuttle missions, including three as commander...

  • Richard H. Truly
  • Henry W. Hartsfield, Jr
    Henry Hartsfield
    Henry Warren "Hank" Hartsfield, Jr. is a retired United States Air Force officer and a former USAF and NASA astronaut who logged over 480 hours in space.-Personal:...

  • William E. Thornton
    William E. Thornton
    William Edgar Thornton is a former NASA Astronaut. Thornton was born in Faison, North Carolina, and is married with two sons to the former Elizabeth Jennifer Fowler of Hertfordshire, England.-Education:...

Mission parameters

  • Mass
    Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

    20847 kg (45,959.8 lb)
  • Maximum Altitude: 440 km (273.4 mi)
  • Distance: 34.5 million miles (55,500,000 km)
  • Launch Vehicle: Saturn IB
    Saturn IB
    The Saturn IB was an American launch vehicle commissioned by the National Aeronautics and Space Administration for use in the Apollo program...

  • Perigee
    Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...

    422 km (262.2 mi)
  • Apogee: 437 km (271.5 mi)
  • Inclination
    Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...

  • Period
    Orbital period
    The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...

    93.11 min


  • 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
  • EVA 1 Start: November 22, 1973, 17:42 UTC
  • EVA 1 End: November 23, 00:15 UTC
  • Duration: 6 hours, 33 minutes
  • Carr and Pogue - EVA 2
  • EVA 2 Start: December 25, 1973, 16:00 UTC
  • EVA 2 End: December 25, 23:01 UTC
  • Duration: 1 hour, 01 minute
  • Carr and Gibson - EVA 3
  • EVA 3 Start: December 29, 1973, 17:00 UTC
  • EVA 3 End: December 29, 20:29 UTC
  • Duration: 3 hours, 29 minutes
  • Carr and Gibson - EVA 4
  • EVA 4 Start: February 3, 1974, 15:19 UTC
  • EVA 4 End: February 3, 20:38 UTC
  • Duration: 5 hours, 19 minutes

Mission highlights

Skylab 4 was the last Skylab mission.

The crew arrived on Skylab to find that they had company up there - three figures dressed in flight suits. Upon closer inspection, they found their companions were three dummies, complete with Skylab 4 mission patches and name tags which had been left there by Al Bean, Jack Lousma, and Owen Garriott at the end of Skylab 3.

The all-rookie astronaut crew had problems adjusting to the same workload level as their predecessors when activating the workshop. Things got off to a bad start after the crew attempted to hide one astronaut's early space sickness from flight surgeons, a fact discovered by mission controllers after downloading onboard voice recordings. 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.

As the activation of Skylab progressed, the astronauts complained of being pushed too hard. Ground crews disagreed; they felt that the astronauts were not working long enough or hard enough. During the course of the mission, this culminated in a radio conference to air frustrations. Following this, the workload schedule was modified, and by the end of their mission the crew had completed even more work than had been planned before launch. The experiences of the crew and ground controllers provided important lessons in planning subsequent manned spaceflight work schedules.

On Thanksgiving Day
Thanksgiving (United States)
Thanksgiving, or Thanksgiving Day, is a holiday celebrated in the United States on the fourth Thursday in November. It has officially been an annual tradition since 1863, when, during the Civil War, President Abraham Lincoln proclaimed a national day of thanksgiving to be celebrated on Thursday,...

, Gibson and Pogue accomplished a 6 hour spacewalk. The first part of their spacewalk was spent replacing film in the solar observatory. The remainder of the time was used to repair a malfunctioning antenna.

The crew reported that the food was good, but slightly bland. The crew would have preferred to use more condiments to enhance the taste of the food. The amount of salt they could use was restricted for medical purposes. The quantity and type of food consumed was rigidly controlled because of their strict diet.

Seven days into their mission, a problem developed in the Skylab attitude control gyroscope
A gyroscope is a device for measuring or maintaining orientation, based on the principles of angular momentum. In essence, a mechanical gyroscope is a spinning wheel or disk whose axle is free to take any orientation...

 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
Lubrication is the process, or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each another, by interposing a substance called lubricant between the surfaces to carry or to help carry the load between the opposing surfaces. The interposed...

. 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.

The crew spent many hours studying the Earth. Carr and Pogue alternately manned controls, operating the sensing devices which measured and photographed selected features on the Earth's surface. The crew also made solar observations, recording about 75,000 new telescopic images of the Sun. Images were taken in the X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

, ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

, 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
Solar flare
A solar flare is a sudden brightening observed over the Sun surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy . The flare ejects clouds of electrons, ions, and atoms through the corona into space. These clouds typically reach Earth a day...


On December 13, the crew sighted Comet Kohoutek
Comet Kohoutek
Comet Kohoutek, formally designated C/1973 E1, 1973 XII, and 1973f, was first sighted on 7 March 1973 by Czech astronomer Luboš Kohoutek. It attained perihelion on 28 December that same year....

 and trained the solar observatory and hand-held cameras on it. 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.

The crew also photographed the Earth from orbit. Despite instructions not to do so, the crew (perhaps inadvertently) photographed Area 51
Area 51
Area 51 is a military base, and a remote detachment of Edwards Air Force Base. It is located in the southern portion of Nevada in the western United States, 83 miles north-northwest of downtown Las Vegas. Situated at its center, on the southern shore of Groom Lake, is a large military airfield...

, 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.

Skylab 4 completed 1,214 Earth orbits and four EVAs totalling 22 hours, 13 minutes.
They traveled 34.5 million miles (55,500,000 km) in 84 days, 1 hour and 16 minutes in space.

The three astronauts had joined NASA in the mid-60s, 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 all three retired from NASA before the first Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

 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.

Spacecraft location

The Skylab 4 command module is on display at the National Air & Space Museum in Washington DC.

Mission insignia

The triangular patch 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 insignia include a comet in the top curve because of studies made of the Comet Kohoutek
Comet Kohoutek
Comet Kohoutek, formally designated C/1973 E1, 1973 XII, and 1973f, was first sighted on 7 March 1973 by Czech astronomer Luboš Kohoutek. It attained perihelion on 28 December that same year....

 but these were not apparently worn during the flight.

See also

  • Extra-vehicular activity
    Extra-vehicular activity
    Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...

  • List of spacewalks
  • Splashdown (spacecraft landing)
    Splashdown (spacecraft landing)
    Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by American manned spacecraft prior to the Space Shuttle program. It is also possible for the Russian Soyuz spacecraft and Chinese Shenzhou spacecraft to land in water, though this is only a contingency...

Further reading

  • Gilles Clement, Fundamentals of Space Medicine, Microcosm Press, 2003. pp. 212.
  • Lattimer, Dick (1985). All We Did was Fly to the Moon. Whispering Eagle Press. ISBN 0-9611228-0-3.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.