Greg 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 answer. 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. Dale > -----Original Message----- > From: George Roberts [mailto:gr@gr5.org] > 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 > http://gr5.org > > _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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