[amsat-bb] Re: ISS/STS-126 Position?
Alan Sieg WB5RMG
wb5rmg at somenet.net
Mon Nov 17 07:56:04 PST 2008
> Do the keps for the shuttle become in accurate at some point .. ?
The KEPs published before a shuttle launch are typically for orbital
insertion at an altitude and velocity that allows them to 'catch up'
to ISS in it's orbit. Once they match up, the shuttle has to 'slow down'
a bit to keep from passing ISS. They are obviously perfectly matched when
docking occurs. Once they are hard-latched together and properly oriented
along the velocity vector - it becomes stable again and the old ISS KEP set
will begin to drift from accurate as slight adjustments have been made.
Look for a new set of ISS KEPs with a date 'after docking' to have the best
positions during joint ops. Sometimes before the shuttle leaves ISS, they
use 'shuttle power' to increase ISS altitude - again a new KEP is needed.
In general, a KEP data set is only useful, until something changes . . .
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