From: mark@unicorn.com
Date: Mon Dec 14 1998 - 06:07:08 MST
Spike Jones [spike66@ibm.net] wrote:
>> I'm not sure, but don't you get EM shielding during atmospheric
>> reentry due to the plasma screen?
>yes. this is a major shortcoming of gps guided exoatmospheric
>devices. at typical reentry velocities you have only a very few
>(typically 3) seconds to reacquire gps and react.
Why would this be a problem? At least for the shuttle and other shallow
reentry vehicles the shielding only occurs below it; the shuttle is now
in continuous contact with the ground via the TDRS sattelites using the
upper antennae. I guess that a much steeper re-entry might block out
signals from above as well.
Of course the fundamental flaw of all GPS-guided weaponry is GPS-faking
or GPS-jamming. Relying on external signals to tell you your position is
always risky.
Mark
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