RE: Eccentricity

From: Bob Christy (
Date: Fri Jun 09 2006 - 03:41:39 EDT

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    There are four reasons that I can think of but there will be others:
    An operational satellite needing to reach a range of altitudes (eg for
    radiation research)
    An operational satellite that needs to reach geosynchronous-like altitudes
    over the polar regions and stay there for long periods to allow coverage in
    areas where the elevation of a geosynchronous satellite above the horizon
    would be too low (eg Molniya, OKO),
    An Earth-imaging satellite keeping a consistent, low perigee for photography
    and varying its apogee to control the geographical location of perigee.
    Changing apogee changes the orbital period and thereby the relative position
    of the ground track (eg military reonsat),
    A satellite such as the R/B that you instanced in a transfer orbit. It has
    been used to push an operational satellite from LEO to high altitude, then a
    further rocket or satellite onboard engine has been used to circularise the
    satellite orbit after separation (eg geosynchronous comsat).
    Some thoughts in as few words as possible but hopefully not too 'muddy'.
    Bob Christy
    > -----Original Message-----
    > From: Tom Wagner [] 
    > Sent: 09 June 2006 01:39
    > To:
    > Subject: Eccentricity
    > About satellite orbit eccentricity. What's the advantage of a 
    > satellite having a permanent highly eccentric earth orbiting orbit?
    > What general kind of satellites have them? I see that some 
    > Delta satellites do. The DELTA-4 R/B, although, not a working 
    > satellite, has an eccentricity in the TLE that's listed as 
    > being about 0.7!
    > Thanks,
    >  Tom  Iowa USA
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