Re: shoot down questions

From: George Roberts (gr@gr5.org)
Date: Sun Feb 17 2008 - 15:20:20 UTC

  • Next message: Ted Molczan: "Updated elements of USA 193"

    "shoot down" should be "blow up" or maybe "slam" or "cut in front".
    
    > I have been thinking about this shoot down and trying to figure some things
    > out as to my chances of seeing something reenter over Lebanon PA USA. I have
    
    If "slapped" near Hawaii I think your chances are very slim in PA.  I expect 
    many pieces to enter within an orbit and most of the rest spread out over a 
    week.  Because the inclination is high (58.5 degrees) it won't pass over PA for 
    several orbits afterward.
    
    > Seems to me the best place to be
    > would be about half an orbit ahead of the sat when intercept occurs.
    
    The best place would be ahead of the orbit within view of the intercept. 
    Assuming circular orbit or significant delta v then it's true that pieces that 
    have a delta v that slows them down at impact will have their perigee half an 
    orbit ahead, but those orbits may "intersect the earth" long before they get to 
    perigee.  All the pieces will have orbits that pass through the impact point one 
    orbit later but many of those orbits will take them into atmosphere too thick to 
    allow these pieces to achieve a full orbit. Any pieces accelerated up (away from 
    earth) will have a perigee more than half an orbit later.  Pieces accelerated 
    down will have a new perigee less than half an orbit later.  In other words, the 
    point opposite the earth of the intercept won't necessarily have significantly 
    more pieces deorbiting than the rest of that first orbit after intercept.
    
    I read that this will be a kinetic only kill (no warhead explosion) which 
    implies that most of the delta v will slow down the satellite pieces which might 
    mean much of the debris will come down within half an orbit.
    
    - George Roberts
    http://gr5.org
    
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