Shuttle Questions Q & A (Part 3)

• #720 by psloss on 06 Aug, 2007 11:35
• Quote

  henrycheck - 6/8/2007  6:22 AM
  
  Possible considerations would be the allowable time between launch and the two IUS firings (thermal and power issues), the need to have the IUS burns occur within the tracking view of the IUS control center at White Sands, and a maximum amount of drift from the initial geostationary longitude to the final orbital location.

  Another example from the STS-7 press kit:
  
  

  Quote

  The opening of the first segment of the launch window is driven by the earth horizon sensor (EHS) sun "cutout" constraint on the Palapa B spacecraft for a revolution 19A injection. This opening time also roughly corresponds to the revolution 113 Edwards Air Force Base landing lighting constraint. This first segment is closed by an earth horizon sensor constraint on the Anik C spacecraft for a revolution 8A injection.
  
  The opening of the second segment is driven by an earth horizon sensor Palapa B constraint for a revolution 19A injection. The second segment is closed by the aft thermal constraint on the Anik C for a revolution 8A injection.
• #721 by Jim on 06 Aug, 2007 12:10
• Quote

  henrycheck - 6/8/2007  6:22 AM
  
  Possible considerations would be the allowable time between launch and the two IUS firings (thermal and power issues), the need to have the IUS burns occur within the tracking view of the IUS control center at White Sands, and a maximum amount of drift from the initial geostationary longitude to the final orbital location.
  
  

  
  IUS control center was in the AFSCF and the burns could be in view of the many AFSCN stations
• #722 by henrycheck on 06 Aug, 2007 13:29
• Quote

  Jim - 6/8/2007  8:10 AM
  
  

  Quote

  henrycheck - 6/8/2007  6:22 AM
  
  Possible considerations would be the allowable time between launch and the two IUS firings (thermal and power issues), the need to have the IUS burns occur within the tracking view of the IUS control center at White Sands, and a maximum amount of drift from the initial geostationary longitude to the final orbital location.
  
  

  
  IUS control center was in the AFSCF and the burns could be in view of the many AFSCN stations

  Jim,
  
  You're the undoubted expert here but I have some recollection of early IUS missions requiring direct White Sands tracking. I also recall a launch where there was an issue with the availability of the White Sands tracking site, although that might be the drugs from the sixties playing tricks with me.
  
  
  
• #723 by psloss on 06 Aug, 2007 13:43
• Quote

  henrycheck - 6/8/2007  9:29 AM
  
  I also recall a launch where there was an issue with the availability of the White Sands tracking site, although that might be the drugs from the sixties playing tricks with me.

  This is a wild "reach," but is it possible that you're thinking of delays to STS-8 and STS-9 in order to allow TDRS-1 verification testing (at White Sands) to progress?
  
• #724 by henrycheck on 06 Aug, 2007 14:57
• Quote

  psloss - 6/8/2007  9:43 AM
  
  

  Quote

  henrycheck - 6/8/2007  9:29 AM
  
  I also recall a launch where there was an issue with the availability of the White Sands tracking site, although that might be the drugs from the sixties playing tricks with me.

  This is a wild "reach," but is it possible that you're thinking of delays to STS-8 and STS-9 in order to allow TDRS-1 verification testing (at White Sands) to progress?
  

  
  
  The circumstance I'm remembering was after the down period following the first IUS partial failure on STS-6. Might only have been a launch hold or a one-or-two day postponement. Don’t waste too much time researching this as I sort of remember Elvis being at the launch.
  
  
• #725 by psloss on 06 Aug, 2007 15:19
• Quote

  henrycheck - 6/8/2007  10:57 AM
  
  The circumstance I'm remembering was after the down period following the first IUS partial failure on STS-6. Might only have been a launch hold or a one-or-two day postponement. Don’t waste too much time researching this as I sort of remember Elvis being at the launch.

  No worries -- just wondering...
  
• #726 by Jim on 06 Aug, 2007 16:57
• Quote

  henrycheck - 6/8/2007  9:29 AM
  
  

  Quote

  Jim - 6/8/2007  8:10 AM
  
  

  Quote

  henrycheck - 6/8/2007  6:22 AM
  
  Possible considerations would be the allowable time between launch and the two IUS firings (thermal and power issues), the need to have the IUS burns occur within the tracking view of the IUS control center at White Sands, and a maximum amount of drift from the initial geostationary longitude to the final orbital location.
  
  

  
  IUS control center was in the AFSCF and the burns could be in view of the many AFSCN stations

  Jim,
  
  You're the undoubted expert here but I have some recollection of early IUS missions requiring direct White Sands tracking. I also recall a launch where there was an issue with the availability of the White Sands tracking site, although that might be the drugs from the sixties playing tricks with me.
  
  
  

  
  TDRS control center is a White Sands
• #727 by SpaceNutz SA on 06 Aug, 2007 21:54

• Quote

  MKremer - 5/8/2007 9:00 AM It may be easier to think of the ISS orbit track as a solid line (a circle around the Earth, angled at 51.6 degrees) - as the Earth rotates, that solid line keeps moving further West every second (the orbit is fixed - the Earth rotates underneath it). If you think about it that way, you can see the Shuttle has a limited period of time to launch.....

  Spent some time pondering this which prompts another question.  When the earth rotates under this orbital circle,  KSC can pass under this circle in 2 different positions each day - one where the ISS has a NE track and the other on a SE track.  Obviously the launch trajectory would be different in each case.  Is either of these situations prefered?  Is the shuttle equipped (by way of different launch trajectories) for each case? 

  BTW thanks for the reference to the orbital mechanics tutorials sites.  Been doing the online tutorials with varying degrees of success.

• #728 by DaveS on 06 Aug, 2007 22:02
• Quote

  SpaceNutz SA - 6/8/2007  11:54 PM
  Is either of these situations prefered?

  Yes, they always launch on Ascending Node pass, this when the track travells up towards the north pole as that's where the TAL sites are, in addition to that you pass over the Atlantic during early launch.
  
  Launching on a Descending Node pass you wouldn't have access to any of the TAL sites plus you would come dangerously close to dumping the SRBs into Cuban or Bahamas waters.
  Just imagine all the political trouble NASA would have to go through just to recover the spent SRBs.
• #729 by Jorge on 06 Aug, 2007 22:03
• Quote

  SpaceNutz SA - 6/8/2007  4:54 PM
  
  

  Quote

  MKremer - 5/8/2007 9:00 AM It may be easier to think of the ISS orbit track as a solid line (a circle around the Earth, angled at 51.6 degrees) - as the Earth rotates, that solid line keeps moving further West every second (the orbit is fixed - the Earth rotates underneath it). If you think about it that way, you can see the Shuttle has a limited period of time to launch.....

  Spent some time pondering this which prompts another question.  When the earth rotates under this orbital circle,  KSC can pass under this circle in 2 different positions each day - one where the ISS has a NE track and the other on a SE track.  Obviously the launch trajectory would be different in each case.  Is either of these situations prefered?

  
  The northerly trajectory is not only preferred, the southerly one is forbidden due to range safety considerations for SRB splashdown/ET debris footprint.
  
  

  Quote

   Is the shuttle equipped (by way of different launch trajectories) for each case?

  
  No.
• #730 by SpaceNutz SA on 06 Aug, 2007 22:19
• OK - understood.   How is commercial shipping traffic restricted in the SRB splashdown zone?   Does NASA (or the US) have jurisdiction over that area of ocean during launch?   I'd guess some precautions would need to be considered aganst and SRB landing on the deck of a commercial vessel.
• #731 by DaveS on 06 Aug, 2007 22:46
• Quote

  SpaceNutz SA - 7/8/2007  12:19 AM
  
  OK - understood.   How is commercial shipping traffic restricted in the SRB splashdown zone?   Does NASA (or the US) have jurisdiction over that area of ocean during launch?   I'd guess some precautions would need to be considered aganst and SRB landing on the deck of a commercial vessel.

  Yes, it's called the Launch Hazard Area(LHA). The Superintendent for Range Operations(SRO) can call a hold in countdown if a boat goes into the restricted waters. Same thing goes for unauthorized aircraft.
  
  Here's the LHA notice for STS-118: http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=8328&start=51#M167374
• #732 by Jim on 06 Aug, 2007 23:57
• Quote

  SpaceNutz SA - 6/8/2007  6:19 PM
  
  OK - understood.   How is commercial shipping traffic restricted in the SRB splashdown zone?   Does NASA (or the US) have jurisdiction over that area of ocean during launch?   I'd guess some precautions would need to be considered aganst and SRB landing on the deck of a commercial vessel.

  
  A Notice to Mariners is issued
  
  It is in international waters, no one has jurisdiction.
  
• #733 by shuttlefan on 07 Aug, 2007 13:39
• After an orbiter is built, can every inch of its wiring be inspected, or is there some that the technicians can't get at?  
• #734 by DaveS on 07 Aug, 2007 13:45
• Quote

  shuttlefan - 7/8/2007  3:39 PM
  
  After an orbiter is built, can every inch of its wiring be inspected, or is there some that the technicians can't get at?  

  There's some wiring between the crew module and the forward fuselage that cannot be inspected.
• #735 by el_nino on 07 Aug, 2007 17:44
• The problems with the SRB's before mission STS-51L have been well documented.  I know that during the down time between STS-51L and STS-26 that the SRB's were redesigned with a 3rd o-ring, heaters, etc.  Have there been any problems with the SRB's that could have caused another disaster during launch since STS-26?
• #736 by shuttlefan on 07 Aug, 2007 17:52
• Quote

  el_nino - 7/8/2007  12:44 PM
  
  The problems with the SRB's before mission STS-51L have been well documented.  I know that during the down time between STS-51L and STS-26 that the SRB's were redesigned with a 3rd o-ring, heaters, etc.  Have there been any problems with the SRB's that could have caused another disaster during launch since STS-26?

  
  Basically, no. There were some concerns in 1993 with the chamber pressures in the SRBs. On some launches one SRB had more chamber pressure than the other one. That was was taken care of.(Maybe Jim or somebody could elaborate more on this.) Also in 1995 there was some very minor o-ring erosion discovered after STS-71 and STS-70 but that was also corrected.
  Also in 1996 on STS-79, some of the nozzle insulation was eroded but prior to the next flight, STS-80, they took care of it. In terms of nearly causing a disaster, though, I don't think there were any major problems after 51-L.
• #737 by shuttlefan on 07 Aug, 2007 17:54
• Quote

  DaveS - 7/8/2007  8:45 AM
  
  

  Quote

  shuttlefan - 7/8/2007  3:39 PM
  
  After an orbiter is built, can every inch of its wiring be inspected, or is there some that the technicians can't get at?  

  There's some wiring between the crew module and the forward fuselage that cannot be inspected.

  
  That wiring would probably be less-susceptable to damage though, because it gets left alone, correct?
• #738 by Endeavour118 on 07 Aug, 2007 18:43
• what was the first NIGHT launch after the challenger disaster?
• #739 by psloss on 07 Aug, 2007 18:47
• Quote

  Endeavour118 - 7/8/2007  2:43 PM
  
  what was the first NIGHT launch after the challenger disaster?

  STS-33