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Tue May 14, 2019, 07:17 PM

46 Years Ago Today; Skylab is launched from Cape Canaveral

https://en.wikipedia.org/wiki/Skylab


Launch of the modified Saturn V rocket carrying the Skylab space station

Skylab was the first space station launched and operated by NASA, occupied for about 24 weeks between May 1973 and February 1974; it was the only space station that the United States has operated exclusively. It fell back to Earth amid worldwide media attention in 1979. Skylab included a workshop, a solar observatory, and several hundred life science and physical science experiments.

Skylab was launched unmanned into low Earth orbit by a modified Saturn V rocket, with a weight of 170,000 pounds (77,000 kg). This was the final mission for the Saturn V rocket, famous for carrying the manned Moon landing missions. Three subsequent missions delivered three-astronaut crews in the Apollo command and service module (Apollo CSM) launched by the smaller Saturn IB rocket. For the final two manned missions to Skylab, NASA assembled a backup Apollo CSM/Saturn IB in case an in-orbit rescue mission was needed, but this vehicle was never flown. The station was damaged during launch when the micrometeoroid shield tore away from the workshop, taking one of the main solar panel arrays with it and jamming the other main array. This deprived Skylab of most of its electrical power and also removed protection from intense solar heating, threatening to make it unusable. The first crew deployed a replacement heat shade and freed the jammed solar panels to save Skylab. This was the first time that a repair of this magnitude was performed in space.

Skylab included the Apollo Telescope Mount (a multi-spectral solar observatory), a multiple docking adapter with two docking ports, an airlock module with extravehicular activity (EVA) hatches, and the orbital workshop, the main habitable space inside Skylab. Electrical power came from solar arrays and fuel cells in the docked Apollo CSM. The rear of the station included a large waste tank, propellant tanks for maneuvering jets, and a heat radiator. Astronauts conducted numerous experiments aboard Skylab during its operational life. The telescope significantly advanced solar science, and observation of the sun was unprecedented. Astronauts took thousands of photographs of Earth, and the Earth Resources Experiment Package (EREP) viewed Earth with sensors that recorded data in the visible, infrared, and microwave spectral regions. The record for human time spent in orbit was extended beyond the 23 days set by the Soyuz 11 crew aboard Salyut 1 to 84 days by the Skylab 4 crew.

Later plans to reuse Skylab were stymied by delays in development of the Space Shuttle, and Skylab's decaying orbit could not be stopped. Skylab's atmospheric reentry began on July 11, 1979. Before re-entry, NASA ground controllers tried to adjust Skylab's orbit to minimize the risk of debris landing in populated areas, targeting the south Indian Ocean, which was partially successful. Debris showered Western Australia, and recovered pieces indicated that the station had disintegrated lower than expected. As the Skylab program drew to a close, NASA's focus had shifted to the development of the Space Shuttle. NASA space station and laboratory projects included Spacelab, Shuttle-Mir, and Space Station Freedom, which was merged into the International Space Station.

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Skylab configuration as planned

Operational history
Completion and launch

On August 8, 1969, the McDonnell Douglas Corporation received a contract for the conversion of two existing S-IVB stages to the Orbital Workshop configuration. One of the S-IV test stages was shipped to McDonnell Douglas for the construction of a mock-up in January 1970. The Orbital Workshop was renamed "Skylab" in February 1970 as a result of a NASA contest. The actual stage that flew was the upper stage of the AS-212 rocket (the S-IVB stage, S-IVB 212). The mission computer used aboard Skylab was the IBM System/4Pi TC-1, a relative of the AP-101 Space Shuttle computers. A Saturn V originally produced for the Apollo program—before the cancellation of Apollo 18, 19, and 20—was repurposed and redesigned to launch Skylab. The Saturn V's upper stage was removed, but with the controlling Instrument Unit remaining in its standard position.

Skylab was launched on May 14, 1973 by the modified Saturn V. The launch is sometimes referred to as Skylab 1, or SL-1. Severe damage was sustained during launch and deployment, including the loss of the station's micrometeoroid shield/sun shade and one of its main solar panels. Debris from the lost micrometeoroid shield further complicated matters by pinning the remaining solar panel to the side of the station, preventing its deployment and thus leaving the station with a huge power deficit.

Immediately following Skylab's launch, Pad A at Kennedy Space Center Launch Complex 39 was deactivated, and construction proceeded to modify it for the Space Shuttle program, originally targeting a maiden launch in March 1979. The manned missions to Skylab would occur using a Saturn IB rocket from Launch Pad 39B.

SL-1 was the last unmanned launch from LC-39A until February 19, 2017, when SpaceX CRS-10 was launched from there.

Manned missions

Skylab in orbit in 1973 as flown, docking ports in view

Three manned missions, designated SL-2, SL-3 and SL-4, were made to Skylab. The first manned mission, SL-2, launched on May 25, 1973 atop a Saturn IB and involved extensive repairs to the station. The crew deployed a parasol-like sunshade through a small instrument port from the inside of the station, bringing station temperatures down to acceptable levels and preventing overheating that would have melted the plastic insulation inside the station and released poisonous gases. This solution was designed by NASA's "Mr. Fix It" Jack Kinzler, who won the NASA Distinguished Service Medal for his efforts. The crew conducted further repairs via two spacewalks (extra-vehicular activity, or EVA). The crew stayed in orbit with Skylab for 28 days. Two additional missions followed, with the launch dates of July 28, 1973 (SL-3) and November 16, 1973 (SL-4), and mission durations of 59 and 84 days, respectively. The last Skylab crew returned to Earth on February 8, 1974.

In addition to the three manned missions, there was a rescue mission on standby that had a crew of two, but could take five back down.

Skylab 2: launched May 25, 1973
Skylab 3: launched July 28, 1973
Skylab 4: launched November 16, 1973
Skylab 5: cancelled
Skylab Rescue on standby


Also of note was the three-man crew of Skylab Medical Experiment Altitude Test, who spent 56 days at low-pressure in 1972 on Earth. This was a spaceflight analog test in full gravity, but Skylab hardware was tested and medical knowledge was gained.

Orbital operations
Days in Space
Mission
Skylab 2 - 28
Skylab 3 - 60
Skylab 4 - 84



Owen Garriott performing an EVA in 1973

Skylab orbited Earth 2,476 times during the 171 days and 13 hours of its occupation during the three manned Skylab expeditions. Each of these extended the human record of 23 days for amount of time spent in space set by the Soviet Soyuz 11 crew aboard the space station Salyut 1 on June 30, 1971. Skylab 2 lasted 28 days, Skylab 3 56 days, and Skylab 4 84 days. Astronauts performed ten spacewalks, totaling 42 hours and 16 minutes. Skylab logged about 2,000 hours of scientific and medical experiments, 127,000 frames of film of the Sun and 46,000 of Earth. Solar experiments included photographs of eight solar flares, and produced valuable results that scientists stated would have been impossible to obtain with unmanned spacecraft. The existence of the Sun's coronal holes were confirmed because of these efforts. Many of the experiments conducted investigated the astronauts' adaptation to extended periods of microgravity.

A typical day began at 6 a.m. Central Time Zone. Although the toilet was small and noisy, both veteran astronauts—who had endured earlier missions' rudimentary waste-collection systems—and rookies complimented it. The first crew enjoyed taking a shower once a week, but found drying themselves in weightlessness and vacuuming excess water difficult; later crews usually cleaned themselves daily with wet washcloths instead of using the shower. Astronauts also found that bending over in weightlessness to put on socks or tie shoelaces strained their stomach muscles.

Breakfast began at 7 am. Astronauts usually stood to eat, as sitting in microgravity also strained their stomach muscles. They reported that their food—although greatly improved from Apollo—was bland and repetitive, and weightlessness caused utensils, food containers, and bits of food to float away; also, gas in their drinking water contributed to flatulence. After breakfast and preparation for lunch, experiments, tests and repairs of spacecraft systems and, if possible, 90 minutes of physical exercise followed; the station had a bicycle and other equipment, and astronauts could jog around the water tank. After dinner, which was scheduled for 6 pm, crews performed household chores and prepared for the next day's experiments. Following lengthy daily instructions (some of which were up to 15 meters long) sent via teleprinter, the crews were often busy enough to postpone sleep.

The station offered what a later study called "a highly satisfactory living and working environment for crews", with enough room for personal privacy. Although it had a dart set, playing cards, and other recreational equipment in addition to books and music players, the window with its view of Earth became the most popular way to relax in orbit.

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Reply 46 Years Ago Today; Skylab is launched from Cape Canaveral (Original post)
Dennis Donovan Tuesday OP
RT Atlanta Tuesday #1

Response to Dennis Donovan (Original post)

Tue May 14, 2019, 07:39 PM

1. Last Saturn V Launch

Wouldve been a helluva launch to see in person. Thanks for posting this!

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