[sci.space.shuttle] Re^2: Radiation danger in high-latitude orbits

gckaplan@rocket.ssl.berkeley.edu (George Kaplan) (08/11/89)

henry@utzoo.uucp (Henry Spencer) writes:
>In article <3929@ncar.ucar.edu> gary@cgdra.ucar.edu (Gary Strand) writes:
>>  How much radiation does the shuttle receive in a high-latitude (as in
>>  the current 'top secret' mission, supposedly) orbit compared to a 
>>  lower-latitude orbit?

>It's not very significant at the latitudes the shuttle reaches in a launch
>from KSC (which cannot launch to extreme latitudes for range-safety reasons),
>unless it gets far enough south to enter the South Atlantic Anomaly.  I don't
>remember the latitudes of the SAA offhand, so I can't be sure of that.  The
>SAA is an area where the inner Van Allen belt is unusually close to Earth,
>due to asymmetry in the Earth's magnetic field.

It's my impression that the SAA extends pretty far north, even to the
equator.  I work for the Extreme Ultraviolet Explorer Project, and we
have to worry about the SAA even though our orbit will have a 28.5 deg
inclination (the lowest inclination you can get from KSC).  We'll have
to shut down our detectors in the SAA since the count rate due to the
particle flux will be too high.

Of course, where you put the boundaries of the SAA is a matter of
degree:  our detectors are much more sensitive to short term radiation
exposure than a human being.

George C. Kaplan                Internet:  gckaplan@sag4.ssl.berkeley.edu
Space Sciences Lab              UUCP:  ...!ucbvax!sag4.ssl!gckaplan
University of California        (415) 643-8610
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