Re: Low perigee question

From: B Gimle @ComHem (@ComHem)
Date: Wed Feb 11 2009 - 10:18:07 UTC

  • Next message: Russell Eberst: "2009FEB10.OBS"

    I haven't seen a general trend to circularize, but I'm no expert either.
    OTOH, the varying attitudes of Moon/Sun vs the satellite orbit make the
    perigee (and apogee) pulsate, by several hundreds of km for apogees
    near the GEO height.
    So it can survive a dip like the one below, and be given a
    grace of a month or more, before the final blow.
    
    The varying effect is almost intuitive - if the Moon (and/or Sun)
    accelerate the satellite during the long time at apogee,
    the perigee will increase - if they decelerate it, the perigee will sink.
    
    There was a report on SeeSat a few years back of an object at similar
    perigee, glowing red-hot but surviving by cooling off while ascending.
    http://www.satobs.org/seesat/Aug-1996/0153.html and preceding.
    
    Losing solar panels and antennas during hig-drag also reduces drag
    on future passes.
    
    Googling for Molniya "red-hot" gives many hits, among them
    http://en.wikipedia.org/wiki/Molniya_orbit ,
    some by Molniya "red-hot"  site:satobs.org or
    Molniya glowing site:satobs.org  or red +perigee glowing site:satobs.org.
    
    If you have a space-track.org account, you can search for Molni
    at Search by Satellite Common Name (decayed or on orbit), then
    Retrieve TLE Data for the interesting Catalog Nos. and desired time periods.
    You can use Orbitel.exe from satobs.org  'Program' page to add apogee x
    perigee to the elset name lines.
    
    My Favourite TLE file has some that once were low in perigee:
    11474 MOLNIYA 1-44 decreasing
    13875 MOLNIYA 3-20 increasing
    13890 MOLNIYA 1-56 increasing
    15738 MOLNIYA 3-24 increasing
    22178 MOLNIYA 3-42 increasing
    22671 MOLNIYA 1-86 decreasing
    23211 MOLNIYA 3-46 decayed; slight increase last 20 days, large fluctuations
    26867 MOLNIYA 3-51 increasing
    27707 MOLNIYA 1-92 increasing
    27834 MOLNIYA 3-53 increasing; now decreasing?
    seen over a 40-day period.
    
    /Björn
    
    ----- Original Message ----- 
    ...
    > much but the orbit tries to circularize with apogee coming down very
    > rapidly whilst perigee height tries to increase but eventually the
    > satellite looses its battle..
    >
    > On the 23 Jan 2009 I reported to SeeSat an observation of an Atlas 5
    > Centaur rocket - 08016B- catalog number #32764.
    > At the time of observation the prediction program used gave an apogee of
    > 4300 kms but a perigee of 87 kms and doing 10 revs/day. Ive just checked
    ...
    > Guess this could make an interesting amateur observation program -- try
    > and observe objects like this as they speed through perigee - just how low
    > can one go without being destroyed ? For the bigger/brighter objects it
    > might even produce quite a spectacular display - there are plenty of
    > objects to watch ....
    >
    
    
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