Re: RCS VALUES + decaying object brightness

Date: Sat Jan 04 2003 - 17:20:53 EST

  • Next message: Edward Lyons: "Shenzhou 4 TLEs"

    As the question on the brightness of decaying objets is treated I would like
    to add a further question to this subject. One problem in seeing a decaying
    object which has a low altitude is the fact, that it can be seen only during
    twilight. When the sky is dark it usually enters in the earth shadow quiet
    quickly. So the opportunity to see low flying objects is very low. One opportunity
    to see such an object would be to detect the glow of the object due to the
    air attrition. It is once more evident that this brightness depends on the
    size, velocity, range to observer, object composition and more, but does
    anybody have an estimate on the brightness due to glow or has anybody some
    experience with such type of observation?
    Maurizio Scaramuzza
    >-- Original-Nachricht --
    >Reply-To: "Daniel Crawford" <>
    >From: "Daniel Crawford" <>
    >To: <>
    >Subject: Re: RCS VALUES + decaying object brightness
    >Date: Sat, 4 Jan 2003 12:13:29 -0600
    >Thanks much to all for the replies to the original question and follow-ups.
    >It is clear that size isn't the only thing that matters.  Angle, shape,
    >distance, etc., are some of the variables that determine how "bright" an
    >object would be WRT an observer.
    >I asked the original question about a year late.  I have learned that it
    >difficult to find/track a piece of small orbiting debris. Just because an
    >object is cataloged, under 200KM, and making an overhead pass, doesn't
    >really mean that you can see it.  I have tried many times, with little
    >success.  I didn't know better...  :)  After lots of non-observes, I know
    >little better.
    >I have an interest of looking for the bits and pieces of things that are
    >really low and coming down soon, regardless of the size.  Perhaps I am
    >foolish, but I figure that some day, if I really keep trying to track down
    >de-orbiting debris, I will see a decay.  Sure, the odds are low, but much
    >better if you know where you should be looking.  It is a free way to pass
    >the time; the only cost is my neighbors looking at me funny at night  :)
    >This brings up the further question.  How "big" would an object need to
    >to see a decay?
    >Again, I know that the odds are small in observing one, but if....
    >An object was decaying overhead.  I would expect that the size of the object
    >would be proportional to the brightness and length of time the object would
    >be visible.  Any thoughts to how bright and how long a decay would be with
    >respect to the mass/surface area of the object?
    >For an example, how bright and how long will Starshine be when it decays?
    >How about the pieces of an object that exploded?  Large rocket bodies and
    >Thanks. Clear, dark and warmest regards.
    >Daniel Crawford
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