Shuttle Questions Q and A (2)

• #660 by shuttlefan on 26 Dec, 2006 20:14
• Quote

  Jim - 26/12/2006  8:18 AM
  
  Some corrections
  
  As mkirk has stated in previous posts, "landing" can be aborted during deorbit burn (and maybe a little after).  Another burn is required to put the shuttle back in a stable orbit.  Fuel state of the shuttle determines if this is possible.
  
  Also there is a "fast sep" scenario where the orbiter disengages from the ET while the SRB's are still burning.  The ability for the orbiter to do this is marginal and some say the orbiter aft attachments (ball joints) would hang up and flip the orbit into the airstream, which would break it up
  
  I stand corrected! I didn't know landing can still be aborted after OMS ignition.
  
  
  
• #661 by ichilton on 26 Dec, 2006 20:34
• Quote

  Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).

  So where abouts is re-entry between the de-orbit burn and landing?
  
  I got home and got NASA TV on half way between the deorbit burn and landing last week but there didn't seem to be any mention of re-entry or a communications break.
  
  Thanks
  
  Ian
  
• #662 by Gary on 26 Dec, 2006 20:37
• Re-entry stars at roughly 400,000 feet and is called Entry Interface.
  From that point until about 150,000 the orbiter is in the heat of re-entry and is where it conducts the S-turns to dissapate the energy gained at launch. I'm sure Jim or someone can give you more info than that.
• #663 by ichilton on 26 Dec, 2006 20:53
• Thanks - so how long after the pre-orbit burn (and before landing) is that and how long does it last?
  
  Thanks
  
  Ian
  
• #664 by Jim on 26 Dec, 2006 20:55
• It varies from mission to mission.
• #665 by ichilton on 26 Dec, 2006 20:57
• Ah.
  
  What about on STS-116?
  
  Thanks
  
  Ian
  
• #666 by mkirk on 26 Dec, 2006 21:17
• Quote

  ichilton - 26/12/2006  3:17 PM
  
  So where abouts is re-entry between the de-orbit burn and landing?
  
  Ian
  

  
  It varies slightly from mission to mission.  For STS-116 the Deorbit burn was planned to occur at 4:26:10 pm Eastern.  Entry Interface occurred about 34 minutes later at 5:00 pm at a range from the runway of 4,333 nautical miles and an altitude of 399,000 feet.  Touchdown was at 5:32 pm.  The highest heating occurs in the Mach 24-Mach 16 range (peak heating is generally around Mach 20-19).  
  
  The high surface heating begins to occur at about 6 minutes after Entry Interface as the orbiter slows to Mach 24 and descends thru about 250,000 feet.
  
  Mark Kirkman
  
  
• #667 by gordo on 26 Dec, 2006 22:59
• Quote

  ichilton - 26/12/2006  9:17 PM
  
  

  Quote

  Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).

  So where abouts is re-entry between the de-orbit burn and landing?
  
  I got home and got NASA TV on half way between the deorbit burn and landing last week but there didn't seem to be any mention of re-entry or a communications break.
  
  Thanks
  
  Ian
  

  
  Generally there is full communication now during re-entry, as the Orbiter can still communicate through TDRS, occasionally the orbiters attitude can block the signal, for example the original comms loss on 107 was due to the fin getting in the way.
• #668 by fdasun on 27 Dec, 2006 03:16
• Quote

  mkirk - 27/12/2006  1:10 AM
  
  When the Deorbit OMS burn is underway the crew will watch the HP begin to count down on the Deorbit Maneuver CRT display, if a systems problem occurs prior to going below 85 nm (safe HP) then the burn can be stopped and the problem evaluated.  If the orbiter is below Safe HP then the orbiter is committed to Entry.
  
  Mark Kirkman
  
  

  
  Thanks.
  So, may I confirm that there is no abort/rescue/escape option for the crew when the orbiter is under safe HP but above ACES bailout altitude (if I remembered correctly, 15Km is ok for an escape with ACES suit weared) ?
• #669 by chksix on 27 Dec, 2006 08:03
• Quote

  Chris Bergin - 26/12/2006  7:27 PM
  
  

  Quote

  ichilton - 26/12/2006  6:18 PM
  
  
  Is there still a radio blackout like the Apollo 13 film?
  
  Thanks
  
  Ian
  

  
  Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
  
  Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.

  
  Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.
• #670 by elmarko on 27 Dec, 2006 11:09
• Quote

  DaveS - 26/12/2006  8:12 PM
  
  

  Quote

  elmarko - 26/12/2006  7:40 PM
  
  And don't forget, thanks to TDRS, the comm dropouts aren't anywhere near as long (I guess, anyway...)

  Nope. Comm and telemetry is pretty solid throughout entry, except for some minor drops when the tail blocks the view of TDRS-W until MILA can take over.

  
  Yeah, that was what I was getting at
  
  Realistically, is there anywhere else that the antennas could be mounted to give better reliability? Or are they constrained by heating, aerodynamics, etc?
• #671 by C5C6 on 27 Dec, 2006 11:22
• wht about my question of crew sleep??    are the astronauts so excited or thrilled that they find it hard to sleep? do they have any sort of training or do they use a drug??
• #672 by elmarko on 27 Dec, 2006 11:27
• Actually I've always wondered about that as well. Say you had a particularly sleepless astronaut. Are things like sleeping pills available, or any other remedies to help them sleep? I imagine whatever they took would have to be pretty well controlled and studied for side effects. You don't want a groggy crew member conducting an EVA, for example.
• #673 by gordo on 27 Dec, 2006 11:44
• Quote

  chksix - 27/12/2006  8:46 AM
  
  

  Quote

  Chris Bergin - 26/12/2006  7:27 PM
  
  

  Quote

  ichilton - 26/12/2006  6:18 PM
  
  
  Is there still a radio blackout like the Apollo 13 film?
  
  Thanks
  
  Ian
  

  
  Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
  
  Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.

  
  Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.

  
  Should be in History, but the 90 secs of extra blackout was unexpected.  Was due in the end to a shallower approach to re-entry.
• #674 by Jim on 27 Dec, 2006 13:30
• Quote

  chksix - 27/12/2006  3:46 AM
  
  

  Quote

  Chris Bergin - 26/12/2006  7:27 PM
  
  

  Quote

  ichilton - 26/12/2006  6:18 PM
  
  
  Is there still a radio blackout like the Apollo 13 film?
  
  Thanks
  
  Ian
  

  
  Yes, although they pretty much have it all scheduled out now. On the STS-115 full re-entry video you hear "We'll be hearing from Houston very soon" and they then hear a call about status pretty much soon after and its a regular call (in the style they know they can communicate).
  
  Don't know if the Apollo 13 film grandstanded the "we should have heard from them by now" on the re-entry, or if it happened like that for real.

  
  Wasn't there an issue with low batteries? They wanted to save them to be sure that the chutes had enough power to deploy. That's why there was silence for longer than usual.

  
  There were separate batteries for ordnance
• #675 by Jim on 27 Dec, 2006 13:31
• Quote

  fdasun - 26/12/2006  10:59 PM
  
  

  Quote

  mkirk - 27/12/2006  1:10 AM
  
  When the Deorbit OMS burn is underway the crew will watch the HP begin to count down on the Deorbit Maneuver CRT display, if a systems problem occurs prior to going below 85 nm (safe HP) then the burn can be stopped and the problem evaluated.  If the orbiter is below Safe HP then the orbiter is committed to Entry.
  
  Mark Kirkman
  
  

  
  Thanks.
  So, may I confirm that there is no abort/rescue/escape option for the crew when the orbiter is under safe HP but above ACES bailout altitude (if I remembered correctly, 15Km is ok for an escape with ACES suit weared) ?

  
  Bail out is only an option in a stable glide below 50k feet.
• #676 by Jim on 27 Dec, 2006 13:32
• Quote

  elmarko - 27/12/2006  7:10 AM
  
  Actually I've always wondered about that as well. Say you had a particularly sleepless astronaut. Are things like sleeping pills available, or any other remedies to help them sleep? I imagine whatever they took would have to be pretty well controlled and studied for side effects. You don't want a groggy crew member conducting an EVA, for example.

  
  They have no real trouble sleeping, but there are pills available.  There have been stories told that towards the end of missions that due to the pace, it is real easy to nod off during moments of inactivity
• #677 by shuttlefan on 27 Dec, 2006 13:35
• Quote

  Jim - 27/12/2006  8:15 AM
  
  

  Quote

  elmarko - 27/12/2006  7:10 AM
  
  Actually I've always wondered about that as well. Say you had a particularly sleepless astronaut. Are things like sleeping pills available, or any other remedies to help them sleep? I imagine whatever they took would have to be pretty well controlled and studied for side effects. You don't want a groggy crew member conducting an EVA, for example.

  
  They have no real trouble sleeping

  
  Alot of astronauts will tell you they are so trained and mentally-prepared for any scenario, that they don't even have trouble sleeping the " night " before launch even when the weather is questionable.
• #678 by Jim on 27 Dec, 2006 13:37
• Quote

  elmarko - 27/12/2006  6:52 AM
  
  

  Quote

  DaveS - 26/12/2006  8:12 PM
  
  

  Quote

  elmarko - 26/12/2006  7:40 PM
  
  And don't forget, thanks to TDRS, the comm dropouts aren't anywhere near as long (I guess, anyway...)

  Nope. Comm and telemetry is pretty solid throughout entry, except for some minor drops when the tail blocks the view of TDRS-W until MILA can take over.

  
  Yeah, that was what I was getting at
  
  Realistically, is there anywhere else that the antennas could be mounted to give better reliability? Or are they constrained by heating, aerodynamics, etc?

  .
  
  There is no issue with reliability or the need for 100% coverage.  Orbiters landed before there was the TDRSS and they experienced blackouts.
  
  4 S-band antennas are mounted in quandrants around the crewn cabin under the tiles.  Which provides the needed coverage on orbit, launch and entry
  
  Why mod the orbiters now when the program is ending in a few years anyways
  
• #679 by shuttlefan on 27 Dec, 2006 13:39
• If, for example they would ever decide to launch a shuttle from Pad B instead of Pad A, would the computers have to be reprogrammed to fly a slightly different flight profile, or does the pad they are launching from make absolutely no difference?