Re: orbital debris report

Date: Tue Feb 04 2003 - 08:34:25 EST

  • Next message: paul: "Re: Cannot get Rick's photos"

    link is pretty much rubbish and has a number of errors in it; in particular
    the reference which you mention, which as Igor points out refers to Kosmos-149 or Kosmos-320,
    sounds like it is rehashing a vague memory of the author; TLEs show rapid decay within a few hours
    of reaching 200 km, not 100 km, while many DoD satellites have had perigees of 90 km 
    and the LOADS-2 (#5382) satellite operated down to 100 km thanks to a high mass-to-area ratio.
    I personally use 80 km as the boundary since very few satellites have survived perigees lower
    than this (a few Molniyas with high apogees have dipped down and then been perturbed out),
    since it roughly corresponds with the physical boundary of the mesopause, is clearly in
    excess of maximum balloon altitudes of around 50 km or so, and matches the 50 mile USAF
    astronaut wings criterion used for the X-15 pilots.
     As for on-orbit/in-orbit, "on orbit" was used a lot by NASA starting in the 1980s
    and my sense of the usage in practice (and it is used, so is de facto correct now) is that
    'on orbit' means usually 'doing stuff while in orbit', especially according to plan.
    Saying 'Discovery is in orbit' and "Discovery is on orbit (or on-orbit)" are both
    correct, but the former has a slightly more passive nuance. One would not normally
    say that a piece of debris was on orbit. That's my sense, I may be wrong.
     - Jonathan
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