Shuttle Questions Q & A (Part 4)

• #240 by Jorge on 08 Dec, 2007 20:24
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  Jim - 7/12/2007  11:57 AM
  
  

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  Jorge - 7/12/2007  12:44 PM
  
  
  It is possible after T+90 seconds. Prior to that, wind shear can change too rapidly for the CDR to keep up. It has never been performed in flight but has been done frequently in sims.
  
  .

  
  Doubtful that orbit still could be achieved.  Sims are one thing.

  
  It depends. If the CDR takes CSS on an otherwise nominal ascent and simply flies the needles, I have no doubt he could achieve orbit, though perhaps not the one originally planned. Of course, you wouldn't take CSS on a nominal ascent in the first place; there would need to be some sort of GNC malfunction that makes AUTO control unsafe.
  
  The sim dynamics are pretty accurate, but the lack of Gs and vibration does make manual control a bit easier than in real life.
• #241 by Jorge on 08 Dec, 2007 20:36
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  pr1268 - 7/12/2007  12:09 PM
  
  

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  Jorge - 7/12/2007 11:44 AM The scene from the Apollo 13 movie grossly exaggerated the motion of the CSM/LM during the manual burn.

  
  Well, I suppose Ron Howard did need to spread out the drama evenly throughout the movie  Did that course correction actually take place?
  
  

  
  Apollo 13 performed four course corrections after the O2 tank rupture, three using the LM DPS and one using the LM RCS. The movie compressed that to one.
  
  

  Quote

  Slightly different topic:  I read somewhere a few months back that there was one STS mission whose entire re-entry and landing were done manually.  Any good links / pointers / info on that?  Thanks for satisfying my curiousity.
  

  
  STS-2, 3, and 4. There was a Usenet thread about this in late 2002.
  
  http://groups.google.com/group/sci.space.shuttle/msg/02bd43eaf4065bba
• #242 by cantuezel on 08 Dec, 2007 21:47
• I have seen some STS & STA approaches toward SLF (e.g. STA-ksc15.wmv at the L2 video KSC-section).
  
  There you can see the HUD-display: At the bottom right position there is a green horizontal line with  one triangle-designator direct above the line and another one at the bottom. At first I thought it could be the Loc for the RWY MLS...but that seems to be wrong.
  
  Do you know what this 2 designators at the horz. line are good for?
• #243 by cantuezel on 08 Dec, 2007 21:50
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  Jim - 8/12/2007  4:09 AM
  
  

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  cantuezel - 8/12/2007  9:49 AM
  
  What could those changes (delta) might be for instance (examples, e.g. blown-tire/bad tiles etc.?)

  
  It is for changes to deactivation procedures for turnaround etc

  
  Yes, but what could be the reasons for such a change in deactivation?
• #244 by DaveS on 08 Dec, 2007 21:59
• Quote

  cantuezel - 8/12/2007  11:47 PM
  Do you know what this 2 designators at the horz. line are good for?

  Commanded and acrual speedbrake setting. Top is commanded speedbrake setting and bottom is actual speedbrake level.
• #245 by Jim on 08 Dec, 2007 22:27
• Quote

  cantuezel - 8/12/2007  5:50 PM
  
  

  Quote

  Jim - 8/12/2007  4:09 AM
  
  

  Quote

  cantuezel - 8/12/2007  9:49 AM
  
  What could those changes (delta) might be for instance (examples, e.g. blown-tire/bad tiles etc.?)

  
  It is for changes to deactivation procedures for turnaround etc

  
  Yes, but what could be the reasons for such a change in deactivation?

  
  For turnaround or tests.
• #246 by cantuezel on 08 Dec, 2007 22:31
• Quote

  DaveS - 8/12/2007  11:59 AM
  
  

  Quote

  cantuezel - 8/12/2007  11:47 PM
  Do you know what this 2 designators at the horz. line are good for?

  Commanded and acrual speedbrake setting. Top is commanded speedbrake setting and bottom is actual speedbrake level.

  
  Thanks Dave!
  
  And where at the HUD can the Localizer (MLS/ILS) of the appropriate RWY be found then (or isnt it presented at the HUD at all)?
• #247 by kimmern123 on 08 Dec, 2007 22:36
• Also HUD-related. On the final flare when the CDR follows the "dot" on the flare at the end there's two horizontal lines on either side of the HUD. Usually the CDR will stop pitching further up than these two lines. What do they indicate? Is it how high the nose should be flared to hit the correct touchdown point or is it the limit for how high the nose can be pitched?
• #248 by Jim on 08 Dec, 2007 23:02
• Quote

  kimmern123 - 8/12/2007  6:36 PM
  
  Also HUD-related. On the final flare when the CDR follows the "dot" on the flare at the end there's two horizontal lines on either side of the HUD. Usually the CDR will stop pitching further up than these two lines. What do they indicate? Is it how high the nose should be flared to hit the correct touchdown point or is it the limit for how high the nose can be pitched?

  
  They are the horizon line
  
• #249 by Jim on 08 Dec, 2007 23:04
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  cantuezel - 8/12/2007  6:31 PM
  
  

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  DaveS - 8/12/2007  11:59 AM
  
  

  Quote

  cantuezel - 8/12/2007  11:47 PM
  Do you know what this 2 designators at the horz. line are good for?

  Commanded and acrual speedbrake setting. Top is commanded speedbrake setting and bottom is actual speedbrake level.

  
  Thanks Dave!
  
  And where at the HUD can the Localizer (MLS/ILS) of the appropriate RWY be found then (or isnt it presented at the HUD at all)?

  
  The guidance bug does glide slope and localizer.
  
  Since you have L2 access, download the SCOM on it
• #250 by dawei on 09 Dec, 2007 10:31
• What is the flash of light (appears to dance around from time to time) at shuttle/ET interface in the live update thread?  (Post is by Chris #22198 in the STS 122 Launch attempt 2).

  ---

  
• #251 by dawei on 09 Dec, 2007 10:39
• From watching further views I am guessing it is a reflection off some sort of material that is moving in the breeze (appears to be a clear plastic looking material).  It startled me at first as it almost looked like a small flame on Nasa TV given the way it "flickered".
• #252 by starbird on 09 Dec, 2007 10:40
• Quote

  dawei - 9/12/2007  6:31 AM
  
  What is the flash of light (appears to dance around from time to time) at shuttle/ET interface in the live update thread?  (Post is by Chris #22198 in the STS 122 Launch attempt 2).

  
  from the ice buildup in that area last flight, I learned that its a strip of mylar that is placed a the interface to keep ice from building up there. It, and any ice that built up on the mylar, is designed to fall off at ignition. It looks like the strip is moving about in the wind.
• #253 by dawei on 09 Dec, 2007 10:46
• Quote

  starbird - 9/12/2007  7:40 PM
  
  

  Quote

  dawei - 9/12/2007  6:31 AM
  
  What is the flash of light (appears to dance around from time to time) at shuttle/ET interface in the live update thread?  (Post is by Chris #22198 in the STS 122 Launch attempt 2).

  
  from the ice buildup in that area last flight, I learned that its a strip of mylar that is placed a the interface to keep ice from building up there. It, and any ice that built up on the mylar, is designed to fall off at ignition. It looks like the strip is moving about in the wind.

  
  Thanks Starbird - that sounds right to me.
• #254 by pr1268 on 09 Dec, 2007 11:03
• Quoting the Wikipedia page on "Atmospheric reentry":
  
  "...On Columbia’s maiden flight (STS-1), astronauts John W. Young and Robert Crippen had some anxious moments during reentry when there was concern about losing control of the vehicle."
  
  What happened, exactly, with respect to the "anxious moments" during reentry?
  
  
  
• #255 by Jim on 09 Dec, 2007 11:54
• Quote

  pr1268 - 9/12/2007  7:03 AM
  
  Quoting the Wikipedia page on "Atmospheric reentry":
  
  "...On Columbia’s maiden flight (STS-1), astronauts John W. Young and Robert Crippen had some anxious moments during reentry when there was concern about losing control of the vehicle."
  
  What happened, exactly, with respect to the "anxious moments" during reentry?
  
  
  

  
  There is the issue, you are quoting wikipedia.  Unless the wikipedia entry has references, don't believe it.
  
  The quote might be referring that there was no way of verifying that  Orbiter could fly through all the entry regimes before the first flight
  
  
• #256 by psloss on 09 Dec, 2007 11:57
• Quote

  pr1268 - 9/12/2007  7:03 AM
  
  Quoting the Wikipedia page on "Atmospheric reentry":
  
  "...On Columbia’s maiden flight (STS-1), astronauts John W. Young and Robert Crippen had some anxious moments during reentry when there was concern about losing control of the vehicle."
  
  What happened, exactly, with respect to the "anxious moments" during reentry?
  

  It might be the situation that Jorge was noting indirectly, on the previous page in this thread:
  http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=10600&start=241#M221623
  
  However, Jim's point still stands -- if that's all that Wikipedia says, without any references, it demonstrates how uncertain one should be about trusting the information there.
  
  Edit -- for the record, Wikipedia does note the situation I'm thinking of, with reference (although whether it's the proper reference is still debatable):
  http://en.wikipedia.org/wiki/STS-1#Mission_anomalies
  
  However, it's not on the "atmospheric reentry" page, which has no footnote or reference for the claim made there.  Without some corroboration, it's just a claim.
  
• #257 by pr1268 on 09 Dec, 2007 12:52

• Quote

  Jim - 9/12/2007  6:54 AM  

  Quote

  pr1268 - 9/12/2007  7:03 AM  Quoting the Wikipedia page on "Atmospheric reentry":  "...On Columbia’s maiden flight (STS-1), astronauts John W. Young and Robert Crippen had some anxious moments during reentry when there was concern about losing control of the vehicle."  What happened, exactly, with respect to the "anxious moments" during reentry?  

   There is the issue, you are quoting wikipedia.  Unless the wikipedia entry has references, don't believe it.  The quote might be referring that there was no way of verifying that  Orbiter could fly through all the entry regimes before the first flight  

  Yes, I know, Wikipedia isn't the best source, but it has its fair moments.  And, yes, the quote wasn't cited, but at the same time it was incredibly vague - that's why I came here to the pros at NSF for the straight skinny on what (if anything) that Wikipedia article was talking about.

  My understanding of what the Wiki article was saying was that STS-1 had off-nominal performance during re-entry due to confusion over the perfect vs. real gas model used in atmospheric modeling data.
   

• #258 by cantuezel on 09 Dec, 2007 13:08
• At the vid "STS-88: Re-entry video with HUD and audio" between 17:10 min. and 17:30 min CAPCOM transmitts to Endev. that there might be a loss of comm for 7 min (TDRS) during roll-reversal.
  
  Do someone know the reason for that? I thought TDRS nowadays guarantees that there wont be a loss of Comm at all?
  
  Thanks for info!
• #259 by Jim on 09 Dec, 2007 13:25
• Quote

  cantuezel - 9/12/2007  9:08 AM
  
  At the vid "STS-88: Re-entry video with HUD and audio" between 17:10 min. and 17:30 min CAPCOM transmitts to Endev. that there might be a loss of comm for 7 min (TDRS) during roll-reversal.
  
  Do someone know the reason for that? I thought TDRS nowadays guarantees that there wont be a loss of Comm at all?
  
  Thanks for info!

  
  Antenna blockage by attitude of the orbiter