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Re: Re-entering space debris questions
Tom,
It's been estimated that about 24,000 meteorites of the 4 oz to 20 lb class
reaches the earth's surface daily. Of this, only about 7,500 reaches land.
Rates of fireballs that don't produce meteorites are probably a lot higher
still. There is a lot of space junk orbiting the earth, but I doubt they are
falling back as fireballs to significanly effect fireball rates as a whole.
I don't think any piece of fallen space junk as been mistakenly identified
as a genuine meteorite. The metal contents have been pretty much identified
to remove any bogus finds.
Space junk do have very low velocities, but I must remind you that most
meteorites that survived entry were traveling less than the 27km/s range and
most likely in the 11 km/s range. This velocity is still very high for space
junk. But something traveling at 11km/s will still appear to be creeping
along. As for relying on color...I wouldn't. I believe the color of orange
may simply be an indication of a slow moving object among other things...that
is slower than say about 40km/s.
Persistent trains are also very prominent and long lasting for meteors that
produced meteorites. I wouldn't rely on persistent trains for space junk
determinations.
Personally, I'd wouldn't worry about trying to make a distinction between
space junk and genuine solar system debris unless a piece was found to be
analyzed. The rates won't be affected much...unless a lot more is put up
there and a sudden massive increase in reentry rates occurs. If you are
really concerned, you might want to consider making meteor
spectrographs....but that is a very time consuming project with lots of luck
involved.
George Zay