Iridium constellation status

From: Rod Sladen (rodsladen@crosswinds.net)
Date: Sat Jan 06 2001 - 15:18:44 PST

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    Summary of Iridium constellation status, 06 January 2001
    
    Orbital	 <-------- Operational satellites -------->    Spares    Failed
    Plane
    
    Plane 1: 74  72  75  70  62  63  64  65  66  67  68    14  21   73?
    Plane 2: 22  23  76  25  45  46  47  11  49  26  03    20       69? 24t 48t
    71t
    Plane 3: 55  28  29  30  31  32  33  57  58  59  60             27t     
    Plane 4: 19  34  35  36  05  06  07  08  04  37  61    51?
    Plane 5: 50  56  52  53  #   10  54  12  13  83  16    84# 86   02? 914t 09t
    911t 85d
    Plane 6: 18  42  40  39  80  17  15  81  38  41  43    77  82   920t 921t 44t
    79d 
    
    Notes:
    
    # Iridium 09 was removed from its position in plane 5 during September 2000.
     As of 06 January 2001, Iridium 84 appears to be in process of being raised
    to fill the gap.
    
    11, 14, 20 and 21 are the second (replacement) satellites known by those names
     They were previously known as 11a, 14a, 20a and 21a respectively.
    
    911, 914, 920, 921 are the (failed) satellites originally known as 11, 14, 20
    and 21 respectively.
    
    ? indicates satellites whose status is unclear, but which are almost certainly
    incapable of being controlled.  But one of these (probably iridium 51) is evidently
    still regarded as usable (see below).
    
    t indicates satellites that have been reported as tumbling out of control.
    
    d indicates satellites that have already decayed:
    
    Iridium 79 decayed on 29 November 2000 (see http://www2.satellite.eu.org/seesat/Nov-2000/0256.html),
    and
    Iridium 85 decayed on 30 December 2000 (see http://www2.satellite.eu.org/seesat/Dec-2000/0409.html).
    
    
    Of the spare satellites, Iridiums 77, 82 and (in recent months) 14 (ex 14a),
    20 (ex 20a) and 21 (ex 21a) have all had their orbits regularly maintained.
     Until the manouver of 05 January 2001, Iridium 84 appears to have had its orbit
    adjusted only once in recent months - back in September 2000 when its orbit
    was raised.  (See http://www2.satellite.eu.org/seesat/Sep-2000/0303.html)
    
    
    At the Iridium Satellite LLC press conference In December 2000 (see http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/iridium/conference-call-Dec-2000.html),
    a figure of 8 operational spares was quoted.  This suggests that one of the
    satellites (probably Iridium 51) flagged above as "?" (status unknown) is still
    regarded as functional.
    
    Recent observations of flares (or of lack of flares, or of flashes indicating
    tumbling) from the relevant satellites (Iridiums 02, 51, 69, 73) would help
    to clarify the situation, as would any elset showing any of these satellites
    being manouvered, though all recent elsets that I have checked show no such
    adjustments.
    
    Iridium 2 has drifted far from its original orbital plane (as have several of
    the tumbling satellites).  At one time, it was suggested that it was deliberately
    being allowed to drift to become the spare in another plane (plane 3?), but
    it has passed that plane over a year ago, and continues to drift, so it is probably
    out of control.  I myself have never seen a flare from Iridium 2, and suspect
    that it may be tumbling.
    
    
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