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Author
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Topic: Skylab's 1977 propellant level and re-entry
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Jim_Voce
Member Posts: 273
From:
Registered: Jul 2016
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posted 02-12-2017 01:13 PM
   
When the last Skylab crew left the station in 1974, NASA expected Skylab to remain in orbit until 1983. Solar activity expanded the earth's atmosphere in the late 1970s and as a consequence, it appeared that Skylab would prematurely enter Earth's atmosphere by 1979.So in 1977, NASA began planning a Skylab reboost mission using the space shuttle. The plan called for the second shuttle flight to rendezvous with Skylab in 1979 and attach an unmanned module to the station which would then boost Skylab up to a higher orbit. But the shuttle's construction was delayed and Skylab made an uncontrolled reentry into the earth’s atmosphere in 1979. So my question is: Did Skylab have enough propellant in its tanks in 1977 to make a "controlled" reentry? Or was Skylab so low on propellant even in 1977 that a controlled reentry was not possible? Hence, a rescue flight of some kind was necessary to either boost the station or help deorbit it. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 02-12-2017 01:55 PM
The cold gas system was not designed nor capable of imparting significant delta v to Skylab — it had low specific impulse (on the order of 10-100 pounds) and the positioning of the thruster nozzles was optimized for its principle function (attitude control). |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 02-12-2017 04:09 PM
Skylab was never capable of a controlled entry since it had no propulsion system. The cold gas ACS was basically used for CMG desaturation and backup attitude control. |
Chuckster01
Member Posts: 942
From: Orlando, FL
Registered: Jan 2014
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posted 02-12-2017 05:59 PM
Trivia question: Do you know the crew slated to boost Skylab back into orbit? And according to my memory that would have been the third shuttle mission (STS-3), not the second, scheduled to save Skylab. |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-12-2017 06:40 PM
Very vague but I seem to recall Fred Haise mentioned as the commander... but that's something I read somewhere long long ago. Could be totally wrong. |
MB
Member Posts: 156
From: Olmsted Falls, Ohio U.S.A.
Registered: Jul 2005
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posted 02-12-2017 07:24 PM
Fred Haise and Gordon Fullerton were the crew training to boost Skylab back into orbit. As preparations for the first shuttle launch kept being delayed past the point of being ready to boost Skylab, Haise retired and Jack Lousma replaced him as commander with Fullerton on STS-3. The Skylab reboots mission would have been an amazing start for the shuttle program! |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-12-2017 11:32 PM
Thanks for that ... brain cells still in order.  Fragments of that magnificent station are still strewn in parts of Western Australia. It dwarfed Salyut 1 in size and the attempts to rescue it from oblivion after launch were astonishing. Skylab was and still is a great part of the program. |
Hart Sastrowardoyo
Member Posts: 3446
From: Toms River, NJ
Registered: Aug 2000
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posted 02-12-2017 11:56 PM
We all agree it was Haise who was scheduled to do the Skylab Rescue (or Reboost) mission. But I seem to recall that Lousma was the original choice as pilot, not Fullerton — because if anything, Lousma had been to Skylab before. |
Chuckster01
Member Posts: 942
From: Orlando, FL
Registered: Jan 2014
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posted 02-13-2017 03:36 PM
We all agree it was Fred Haise as commander of STS-3 but it was Jack Lousma as his pilot for STS-3. Fred Haise (and I have this from Fred) personally quit the program shortly after Skylab's decent back to earth. According to Fred, "He did not want just a ride back to space but a mission like saving Skylab. After the reentry of Skylab he had no mission." After Fred stepped down, Jack Lousma took over as commander of STS-3 and Gordon Fullerton was moved from pilot of STS-4 to pilot of STS-3. Hank Hartsfield was moved from back up to pilot of STS-4. I believe this to be accurate. If anyone has a correction please feel free to chime in. |
Hart Sastrowardoyo
Member Posts: 3446
From: Toms River, NJ
Registered: Aug 2000
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posted 02-13-2017 09:28 PM
NASA photo s78-27531 lists the four OFT crews, including Haise as commander and Lousma as pilot (and Brand as commander and Fullerton as pilot for OFT-4.) |
Jim_Voce
Member Posts: 273
From:
Registered: Jul 2016
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posted 02-18-2017 06:44 AM
I have heard that was an alternative to the shuttle reboost mission. NASA considered flying a crew to Skylab around 1979 and steering the station to reenter the atmosphere over the Pacific Ocean. Has anyone ever heard of this mission? |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-18-2017 06:45 AM
As far as I am aware, at or about the time, NASA was reasonably confident of a controlled re-entry though even though they knew it was imminent. They were fortunate it hit a massive part of uninhabited Western Australia. I can readily recall the chase was on for some salvage. Better than the bottom of the ocean. Made front pages down here. |
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