Re: Shuttle seen from home in Quebec !

From: Markus Mehring (m.m@gmx.net)
Date: Tue Mar 11 2008 - 13:02:12 UTC

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    On Tue, 11 Mar 2008 03:18:40 -0400, you (Jonathan McDowell
    <jcm@head.cfa.harvard.edu>) wrote:
    
    >David, I don't think it was the photo flashes ... I have seen these
    >quasi-periodic flares on previous launches. I guess it's the RCS burns,
    >but they seem awfully bright. I don't suppose it could be the tumbling ET?
    
    The ET starts to tumble *very* slowly after separation, and takes a
    while to pick up a period worth mentioning, certainly quite a few
    minutes - leaving aside sunlight illumination considerations. My money
    would be on the RCS plumes during separation and flip-over maneuvering,
    I think that's the most likely candidate. Maybe worth mentioning here is
    that a few RCSs failed early in the ascent (a controller card went
    dead), so it's probably not ruled out that they used a different set or
    config of thrusters than nominal after separation. If that's even of any
    significance.
    
    Considering the spectacular ET venting that the post-separation video
    from onboard STS-122 showed, I wonder if the ET venting has ever been
    observed from the ground. Granted it's been a few years, but I've seen
    the Shuttle and ET just after separation coming over the hump passing
    over Europe, though I surely didn't notice any signs of venting then.
    
    I'm also wondering if the photo flashes maybe could be observed after
    all, but I don't know how bright they are to begin with. Again on
    STS-122, I've seen the Shuttle passing into and way beyond (its) dusk
    and sunset merely illuminated by what can only have been the payload bay
    floodlights, which came as no little surprise. After shadow entry, it
    was so faint that I had to look past it (avoiding the blind spot in the
    retina) to keep following it with binoculars, but it did work.
    
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