Re: Iridium 56 Flare

From: Tony Beresford (
Date: Sun Mar 19 2000 - 01:03:30 PST

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    At 11:15 19/03/00 , Dale Ireland wrote:
    >Is Iridium attitude control something that requires frequent control
    >from ground stations or is it a rather automatic function that may
    >continue without ground commands for months or more??
    I cant answer that dale, the best person to answer that might be
    some recently unemployed Iridium technical personnel!!
    I can however point out that the orbit plane precesses about 0.3
    degrees a day, so the spin axis has to be adjusted by this amount,
    at least. Also the satellite is from the viewpoint of an inertial observer
    doing 1 rev/orbit. This is quite a slow rate. I suspect the torques
    on the satellite from solar radiation pressure and earth radiation pressure
    mean that the roatation rate has to be controlled on a week by week basis.
    Of course to keep it equal to 1 rev/orbit when you are lowering the
    period is an extra problem.
    Tony Beresford
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