Author Topic: Vandenberg Shuttle mission to repair Landsat  (Read 4023 times)

Offline Ben E

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Vandenberg Shuttle mission to repair Landsat
« on: 12/15/2005 08:09 PM »
Further to an earlier thread, I understand that one mission being considered for Vandenberg in pre-51L days was to repair a Landsat in orbit. I believe that Dave Leestma and Kathy Sullivan practiced refuelling techniques for this mission during their spacewalk on STS-41G.

Does anyone have any further information on this mission? I've seen brief references to the mission, but no real facts.

Thanks

Offline GregM

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RE: Vandenberg Shuttle mission to repair Landsat
« Reply #1 on: 12/17/2005 05:29 PM »
Yes, such a mission had been pencilled in. It was not however, a repair mission. It would have been a servicing mission more like an HST servicing missions. The bus that Landsat used was designed for shuttle servicing, and the vehicle had a RMS grapple fixture built onto it. An orbiter would have driven up to the satellite, grabbed it with the RMS, and locked it down to a workstand in the payload bay just like HST. In the case of Landsat, part of the servicing would have included refuelling the satellite with hydrazine – a very toxic substance.  Refuelling processes had been tested and rehearsed on several STS EVA's in preparation for a mission such as the Landsat. Servicing would have likely taken 2 or 3 EVA's, with one of the EVA’s dedicated exclusively to refuelling. This was in part because the astronauts would have spent time "lying" in the sunshine in the payload bay following their work on the satellite, in order to bake out any hydrazine that may have spilled onto their spacesuits. This was to try to insure that the spacewalking astronauts didn’t bring any hydrazine back into the cabin when they came back in – kind of like taking the time to wash the mud off of your boots outside before coming back into the house.

The refuelling tests that were done were quite successful, and if the mission had actually flown, there is little reason to believe that it would have not gone off successfully. The successful satellite “rescue” missions performed by STS over the years on malfunctioning satellites (Palapa, Westar, Syncom Four, Solar Max, and Intelsat) almost never went off as planned because of unforeseen configurations of the satellites. Only the Syncom 4 rescue went off as planned. The remainder became improvised seat-of-the pants rescue missions when the intended techniques ended up not fitting the satellite. Some of the stuff they did was pretty crazy and daring by today’s standards.

The Landsat mission would have been pretty straightforward compared to those flights.

Offline nethegauner

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RE: Vandenberg Shuttle mission to repair Landsat
« Reply #2 on: 12/20/2005 07:38 AM »
If we are talking about either Landsat 4 or Landsat 5, then the satellite bus used was the same as for SolarMax. Yes, the Multimission Modular Spacecraft (MMS) was specifically designed to be serviced on-orbit by the shuttle and having its instruments swapped out, for example.

Later, a modified MMS was used for the TOPEX/POSEIDON satellite.

A good reference regarding the MMS can be found in "The space shuttle operator's manual", revised edition.

Offline Ben E

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RE: Vandenberg Shuttle mission to repair Landsat
« Reply #3 on: 12/20/2005 10:13 AM »
Thanks GregM and nethegauner,

Do you by any chance have any links to information about the Landsat servicing? Is there anything else at NASA?

Offline nethegauner

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RE: Vandenberg Shuttle mission to repair Landsat
« Reply #4 on: 12/20/2005 11:06 AM »
Quote
Ben E - 20/12/2005  12:13 PM
Do you by any chance have any links to information about the Landsat servicing? Is there anything else at NASA?
At NASA? No idea. I just know that the LANDSAT mission was flight 72-A scheduled for January 2, 1987. It would have been the third flight out of Vandenberg -- also known as STS-3V. I have that info from a manifest posted to net.space on September 5, 1985. Sources from 1986 list different payloads for 72-A, though.

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