Re: Eccentricity

From: Jonathan McDowell (jcm@head.cfa.harvard.edu)
Date: Fri Jun 09 2006 - 16:20:01 EDT

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    Chris said:
    >> (79 x 1,550 km)
    > it seems like it might be a mistake?
    
    Not a mistake. Highly eccentric orbit satellites, especially the Molniyas,
    often end their lives with many days or even weeks in the 70-80 km perigee
    regime. Lunisolar perturbations dip the perigee down to 70-80 km, while
    the apogee is up at 20 to 40 thousand km. On each pass, the satellite dows
    oops does heat up a lot, and loses a lot of velocity due to friction, dropping
    the apogee by many km per pass. But the apogee's so high, and the perigee
    velocity is so fast, that the satellite survives in orbit for an
    extended time - many tens of revolutions even. It's not uncommon for bits
    to fall off and generate short lived debris, but the main satellite does
    remain tracked in orbit until the apogee drops to a few hundred km and
    so the perigee velocity isn't fast enough to survive an atmosphere pass.
    
    Just unintentional aerobraking - kind of like the Mars Recon Orbit
    is doing intentionally at Mars right now.
     Jonathan
    
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