Iridium 73 status mystery

From: Rod Sladen (rodsladen@crosswinds.net)
Date: Tue Jan 23 2001 - 05:39:10 PST

  • Next message: bjorn.gimle@tietotech.se: "Re: Iridium 73 status mystery"

    The 66 satellites in the operational Iridium constellation (which now includes
    Iridium 84), all seem to flare reliably, as indeed they should.  A missing flare
    from a member of the operational constellation would indicate at least an orientation
    error, which would mean that it would not function correctly in its communications
    role.
    
    The spare satellites, Iridium 77, Iridium 82, Iridium 86, Iridium 14 (ex 14a),
    Iridium 20 (ex 20a) and Iridium 21 (ex 21a) all have their orbits regularly
    adjusted, and seem to flare reliably, though flare intensity may vary from that
    predicted.
    
    Iridium 51 (the spare that is believed to be a "partial failure") also seems
    to flare reliably, even though its orbit does not seem to be adjusted.
    
    Iridium 2 seems to be a consistent no-show since at least October 1999.  Likewise,
    Iridium 69 also seems to be a consistent no-show since at least December 1998.
    
    However, no definitive report seems to have appeared on SeeSat-L of tumbling
    or flashing from either of these satellites.
    
    The joker in the pack seem to be Iridium 73!
    
    There are reports of flashing from this satellite:
    http://www2.satellite.eu.org/seesat/Jun-1999/0507.html and
    http://www2.satellite.eu.org/seesat/Aug-2000/0080.html,
    
    a report of Iridium 73 flaring *as expected*:
    http://www2.satellite.eu.org/seesat/Jan-2001/0310.html,
    
    a report of a *no-show* from Iridium 73:
    http://www2.satellite.eu.org/seesat/Aug-2000/0458.html,
    
    and also a report of an *unexpected* flare from Iridium 73:
    http://www2.satellite.eu.org/seesat/Aug-2000/0008.html
    
    Could it be that Iridium 73 is correctly orientated, but that one or more of
    the MMAs are stuck in the wrong position?
    
    It would therefore be helpful if reports of flares/lack of flares in this situation
    indicated which MMA was expected to cause the flare.
    
    I myself have several flare opportunities for Iridium 73 in the near future,
    including some from the right MMA and some from the front MMA.  I even have
    a prediction for a mag. -7 flare tonight, but I also have clouds (and work!)
    -- 
    Rod Sladen, Beeston, Nottinghamshire, UK, 52.923N, 1.219W
    
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