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From: emrath@uiuccsb.UUCP
Newsgroups: net.space
Subject: orbital mechanics ? - (nf)
Message-ID: <15700010@uiuccsb.UUCP>
Date: Thu, 26-Apr-84 14:22:00 EST
Article-I.D.: uiuccsb.15700010
Posted: Thu Apr 26 14:22:00 1984
Date-Received: Sat, 28-Apr-84 11:16:52 EST
Lines: 17
Nf-ID: #N:uiuccsb:15700010:000:727
Nf-From: uiuccsb!emrath    Apr 26 13:22:00 1984

#N:uiuccsb:15700010:000:727
uiuccsb!emrath    Apr 26 13:22:00 1984

I don't remember enough mechanics from high school or college.
I read in Aviation Week & ST that the deorbit burn on the last
shuttle mission resulted in a retrograde delta-v of about 460
feet per second.  This is consistent with the figures of 6000 lbs
thrust per OMS engine, a mass of 75-100 tons, and burn time of 8 min.
However, I figure the shuttle's velocity must be close to 25k fps at
an orbit of 250 nmiles.  I'm suprised that less than a 2% change
brings it down rather than just bringing it to an elliptical orbit.
Is the de-orbit burn done at an orbit just above the atmosphere
so that the new low point is within, thus allowing friction to
take over?

	Perry Emrath, UofIL
	...{decvax|inuxc}!pur-ee!uiucdcs!emrath