Re: plasma trail

From: Markus Mehring (m.m@gmx.de)
Date: Thu Feb 06 2003 - 02:57:18 EST

  • Next message: Markus Mehring: "Re: plasma trail"

    On Wed, 5 Feb 2003 22:06:34 -0800, you ("Dale Ireland"
    <direland@drdale.com>) wrote:
    
    >The were some very interesting video clips on the news tonight taken from
    >inside a Shuttle during a previous reentry. Looking out the front windows
    >from behind the pilot at the bright red glow and looking back at the plasma
    >trail.  questions: How did they get a shot out the back or down the side of
    >the shuttle looking back??
    
    If I understand you correctly, that footage showed a look back into the
    plasma trail, like in a tunnel. That could no doubt be achieved by looking
    through the top windows on the flight deck. The Shuttle enters its entry
    interface with a nose-up attitude of 40, so looking out the top windows
    would enable you to look back into the reverse direction of your flight
    path, and that's of course where the plasma trail is. Have a camera
    installed there at an angle of 40 towards the ceiling looking out the
    window, and it would also look right backwards at that point in the flight.
    Also I guess it wouldn't be impossible for a Mission Specialist on the
    flight deck to hold a camera up in a way that would also look into that
    direction. Maybe not from the MS2 seat, but from the seat to the right of
    it. (MS2 is the center seat right behind the CDR and PLT, assisting them
    with checklists and timelines. On STS-107, this was Kalpana Chawla's duty.)
    But I guess such handheld footage would obviously appear somewhat shaky and
    thus be identifiable.
    On a sidenote, reportedly there have been landings (that is, touchdowns)
    where one of the Mission Specialists wasn't seated, for, uhm, undisclosed
    reasons. I understand this depends on the seniority of such a MS and on
    what the CDR tolerates. But I somewhat doubt that would be the case here,
    considering issues with the transition from zero-G to re-entry G-loads.
    
    >A camera back where the engines are perhaps? I
    >had never seen anything like it... and.. both shots showed very bright
    >flashes every few seconds like electrical discharges not the smooth
    >nonvariable plasma trail that we have been discussing, any idea what that
    >was?
    
    That's the normal irregular atmosphere. Remember that they're hitting the
    atmosphere at very high speed, so they're covering a lot of range and pass
    through a lot of variations in density within a very short time, and that
    translates to the flicker in the ionization, and also to a bit of a rough
    ride. Someone with more knowledge in hypersonic aerodynamics could probably
    explain this a little better than me, in terms of airflow and heat on the
    leading edges of the vehicle and whatnot. The red glow around the Shuttle
    is indeed irregular and flickers quite significantly through the windows,
    but in the "ionization wake" of the Shuttle, this plasma trail soon has
    calmed down and glows fairly steadily for a while, and that's what can be
    seen from the ground.
    
    
    CU!	Markus
    
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