Re: SPOT 1 manoeuvre

From: Thierry Marais (
Date: Fri Nov 21 2003 - 08:26:25 EST

  • Next message: Greg Roberts: "Obs 18 Nov 2003-Part 3"

    Oops ! I was so absorbed in the orbit determination of Greg's unknown
    that I missed Ted's find. Anyway, it is interesting to see that Greg's
    observation led (one more time) to an accurate elset compared to an
    official source, except the mean motion value betraying many manoeuvers.
    For punishment :) I summarize and translate the CNES press release 
    pointed out by Kevin.
    "22 February 1986 :  An Ariane rocket sent SPOT 1 in space. Built for
    a 3 year life, it worked 18 years and gave 2.7 millions earth pictures.
    With the current altitude of 800 km, SPOT 1 could stay in orbit around
    200 years, as it is coming near the end of its operational life, the teams
    of the CNES CST (Centre Spatial de Toulouse) decided to lower the orbit
    perigee to 550 km before a final passivation, and so reduce its life to around
    15 years. During year 2001, a solar panel showed a sudden degradation, 
    loosing 1/9 of power production, fearing an impredictable evolution, CNES
    decided to stop all functions of the payload after applying international 
    recommendations about space debris.
    1000 seconds burns are planned everyday during about ten days. On
    November 17th, SPOT1 has been lowered by 14 km on a circular orbit
    to free the orbit used by SPOT 2, 4 & 5 and avoid collision risks. The
    day after, the flight software and the satellite configuration was adapted
    to the deorbitation process."
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