kaplow@crvax1.DEC (Reach for the Stars) (02/18/86)
The shuttle DOES perform its final minute(s) of main engine burn
pointing down. The size of this down component is quite small compared
to the downrange component. This intentional downthrust is not, however,
wasted energy. While its altitude is decreasing slightly, its speed is
greatly increased to just less than the amount necessary for orbital
velocity (its easier to go faster downhill than uphill). Then the later
OMS burns redirect the speed to the desired orbit.
I beleieve that they want the ET to burn up to prevent the shuttle
orbital path from getting cluttered up with empty ETs. Ask NORAD how
much junk in space it is already tracking. Also thing what a chance
meeting between an orbiter and an ET might do. Now if we had something
useful to do with all of those ETs...
Bob Kaplow
Digital Equipment Corp.
Arlington Heights, IL
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