Re: FENGYUN 1C satellite and debris in 3D

From: Christian Kjrnet (ckjarnet@broadpark.no)
Date: Thu Jan 25 2007 - 18:12:52 EST

  • Next message: Marco Langbroek: "Re: FENGYUN 1C satellite and debris in 3D"

    Tom,
    
    Very nice and illustrative simulated views.
    
    Some thoughts/observations/speculations based on the views and the orbital
    elements of the debris pieces:
    
    1) Except for a couple of the debris objects, the inclinations of the debris
    haven't changed much. That would indicate that the target satellite was hit
    by a coplanar ASAT object, which would be the easiest trajectory anyway in
    order to make a hit. Probably the ASAT object came from below and behind
    with (much?) greater speed than the target. In addition, the similar
    inclinations indicate that the ASAT object did not include an explosive
    charge or the charge did not go off on impact, i.e. the target satellite did
    just suffer a direct hit, whereupon the two objects fragmented/were torn
    apart.
    
    2) The debris objects are in two distinct groups: (a) 29716 to 29732 have
    apogee slightly lower than the target satellite altitude and perigee much
    lower; the lowest is 29716, which is about to decay already; and (b) 29733
    to 29747 have perigee slightly higher than the target satellite and apogee
    much higher, up to ca. 3500 km.
    
    3) Given the described impact scenario, the heaviest remaining piece from
    the target satellite would be the one with the least orbital change
    outwards, i.e. NORAD No. 29733, and the debris pieces that have the most
    change of orbit would be expected to be the smallest/lightest objects.
    Non-central hits causing great spin on the target object could make this
    scenario a bit different when for instance solar panels or other light
    objects are torn off the target by inflicted spin.
    
    4) Most of the debris objects are likely small and faint. According to H-A,
    the target satellite had intrinsic magnitude of 5.5 and max magnitude 4.8.
    One is therefore going to need a telescope to see most of the debris, I
    think.
    
    5) I don't know the answer to the question whether the target satellite was
    hit at perigee; I have not propagated the TLE backwards, and the question is
    not very interesting as the pre-impact orbit was almost circular (860x882
    km).
    
    6) We should first search for 29733, alternatively 29732, as the two likely
    brightest objects.
    
    I am clouded out, so I invite everybody to give it a try.
    
    Best regards,
    
    Christian Kjaernet
    Norway
    
    On 25-01-07 03:13, "Tom Wagner" <sciteach@mchsi.com> wrote:
    
    > I found a way to place a maximum of 17 satellites into a free planetarium
    > program called Celestia . I uploaded 17 recent TLEs for the FENGYOU 1C
    > satellite and debris. Screen captures can be seen at the following URLs.
    > 
    > 
    > 
    > The first two are set up for cross-eyed stereo viewing. All show the debris
    > and the original satellite as 200 km diameter spheres. Can't miss them that
    > way! The original satellite, I believe that's what the TLE that didn't say
    > debris was for, is labeled. It's interesting to see how the inclination of
    > one of the 16 pieces has changed from the original orbit. There may be
    > others like it too.
    > 
    > 
    > 
    > http://i138.photobucket.com/albums/q262/IowaTom/FENGYUN1CDebris.jpg
    > 
    > http://i138.photobucket.com/albums/q262/IowaTom/Fengyun1Corbits.jpg
    > 
    > 
    > 
    > If anyone wants help in learning how to see two images at once, one with
    > each eye, feel free to ask. I've trained many people how to do it.
    > 
    > 
    > 
    > These last two shots show two different perspectives.
    > 
    > 
    > 
    > http://i138.photobucket.com/albums/q262/IowaTom/sideview.jpg
    > 
    > http://i138.photobucket.com/albums/q262/IowaTom/inclinations.jpg
    > 
    > I wonder if it got hit when it was at its perigee?
    > 
    > Tom  Iowa  USA 
    
    
    
    -- 
    Christian Kjśrnet
    
    
    
    
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