Re: Low perigee question

From: Greg Roberts (
Date: Wed Feb 11 2009 - 06:41:30 UTC

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    This is not uncommon - many of the high altitude objects- especially those in 
    GTO orbits have a low perigee and a high apogee and decay rapidly.  The 
    mechanics of how the orbit decays is quite interesting-I think it was discussed 
    on SeeSat quite some time ago - Im not an expert on this so had best not say too 
    much but the orbit tries to circularize with apogee coming down very rapidly 
    whilst perigee height tries to increase but eventually the satellite looses its 
    On the 23 Jan 2009 I reported to SeeSat an observation of an Atlas 5 Centaur 
    rocket - 08016B- catalog number #32764.
    At the time of observation the prediction program used gave an apogee of 4300 
    kms but a perigee of 87 kms and doing 10 revs/day. Ive just checked on this 
    object and the program reports "Object decayed" . At the end of Jnauary it had 
    decreased its orbital period to around 14 revs/day and had an enormous drag 
    Guess this could make an interesting amateur observation program -- try and 
    observe objects like this as they speed through perigee - just how low can one 
    go without being destroyed ? For the bigger/brighter objects it might even 
    produce quite a spectacular display - there are plenty of objects to watch ....
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