RE: Shuttle landing path

From: Dale Ireland (
Date: Thu Jul 21 2011 - 19:37:37 UTC

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    They land on the ascending passes even when they are at night and there are
    nice daylight opportunities on the descending so I don't think that is the
    I have heard the theory about work cycles and disrupting the sleep cycles of
    the ISS crew which is usually on Moscow time. That would still result in a
    similar number of landings from both approaches.
    I pay a lot of attention to them because I am right under the early reentry
    path if they land on descending paths. On MIR missions they had no
    preferences and might change from ascending to descending if there was a
    weather delay, they never do that change now and have only had a couple
    descending landings the past few years.
    I think it has to due with safety concerns but the chances of getting hit by
    debris from a breakup have to be extremely low.
    > -----Original Message-----
    > From: George Roberts [] 
    > Sent: Thursday, July 21, 2011 12:05 PM
    > To: Dale Ireland; 'Roger'
    > Cc: 'SeeSat-L'
    > Subject: Re: Shuttle landing path
    > > > Why did the shuttle almost always land on the ascending 
    > leg of its 
    > > > orbit rather than the descending which gives the whole
    > I'm going to guess random chance.  Certainly for the non-ISS 
    > flights the shuttle only reaches florida latitude so they are 
    > forced to wait until florida is under that point in the 
    > shuttle's orbit.  But for the ISS flights (which go much 
    > further north) they get two chances - an ascending and 
    > descending pass (here ascend/descend refers to latitude, not 
    > altitude). 
    > Florida would pass under these two orbital points twice each 
    > day about 9 hours apart e.g. noon and 9pm every day.  One of 
    > these times is likely during daylight and one likely during 
    > night time and I expect they will go with daylight every time 
    > regardless if it is descending or ascending.  If they are 
    > both during daylight I think they pick the one at the more 
    > convenient time of day (astronauts more alert).  But this is 
    > all a guess based on what I know about orbits and how I might 
    > plan the shuttle landing if it was my job.
    > - George Roberts
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