fisher@dvinci.DEC (Burns Fisher, MRO3-1/E13, 231-4108) (04/30/84)
> I'm surprised that a 2% change in velocity can bring them down...
Yes...the small delta-v just lowers the altitude at the opposite side of
the orbit from the burn so that it is in the atmosphere.
Do a sanity check:
Columbia is orbiting at (very) roughly 4000 miles from the center of the
earth. A altitude change of 2% is about 80 miles. Most STS missions are
orbiting at an altitude (from the surface) in the vicinity of 150 miles.
Lowering part of the orbit by 80 miles brings it to 70 miles, well within the
range of atmospheric friction. I make no representation that velocity change
is linear with altitude (in fact I am sure it is not); this is just a quick
very rough sanity check to help make my assertion plausible to unbelievers.
Burns
UUCP: ... {decvax|allegra|ucbvax}!decwrl!rhea!dvinci!fisher
ARPA: decwrl!rhea!dvinci!fisher@{Berkeley | SU-Shasta}emrath@uiuccsb.UUCP (05/06/84)
#R:decwrl:-750600:uiuccsb:15700011:000:327
uiuccsb!emrath May 5 16:43:00 1984
Thanks, I did that same sanity check, but on the mission in question,
their orbit went to something like 250-290nm, so bringing them down 80
or so wouldn't be enough. I guess you had to be there.
Anyway, it makes me realize that when they say LEO, they mean it!
Perry Emrath, UofIL
...{decvax|inuxc}!pur-ee!uiucdcs!emrath