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Re: When it's a rock! (was, "RE: When Does a Meteorite become a Meteorite?")



So with all this space junk and meteoroid monitoring, has anyone predicted any
fireballs?  Seems like a nice practical use for the data.  What is the
sensitivity of our equipment for monitoring?  Do most  meteoroids just come in
too fast to be detected?

Might we have information when MIR comes down?  I image we will since skylab was
pretty closely monitored.

Cheers,

Jeffrey

GeoZay@aol.com on 09/12/99 05:55:18 PM

To:   meteorite-list@meteoritecentral.com
cc:
Subject:  Re: When it's a rock! (was,    "RE: When Does a Meteorite become a
      Meteorite?")




In a message dated 99-09-11 16:40:46 EDT, you write:

Ginger<<  When it's a piece of space
 junk coming through the atmosphere making the light what do we call it?
(Assuming
 you could tell the difference between space junk and a real rock from space,
in
 flight.) <<

Ginger, I refer to these objects as "pieces of re entering space junk". The
difference of reentering orbiting space junk and a slow meteor is quite
distinct really. Below are some of the differences to look for:

1)Re-entries are rarely if ever brighter than -8 magnitude and typically last
for many tens of seconds, going from horizon to horizon usually with dozens
of fragements trailing.

2) While some meteoric fireballs may be of long duration with numerous
fragments, they would typically be very much brighter than Venus.

3) A fireball lasting a few seconds is unlikely to ever be a satellite re
entry.

4) Is the path consistent with a predicted satellite re-entry? It would be
rare for a reentry to follow an east to west path.

5) If the velocity can be calculated, a satellite renentry will be below 8
km/sec, whereas a meteoric fireball will be above 11 km/ec, and often well
above. Visually, a satellite with a re-entering velocity of less than 8
km/sec is very noticeable when compared to a meteor velocity over about 18
km/sec. They pretty much look like the velocity you normally see for
satellites in the evening or mornings.

ginger>> Most of us amateur astronomer types call all of the smaller ones
 *shooters* out in the field - the big ones are *fireballs*.  Sometimes you
hear
 *bolide* from the more academic folks.<<

I don't have a "pet" name for non fireball meteors other than perhaps a short
nickname for it's shower membership or simply "sporadic". For example, I
might refer to a Quadrantid as simply as a "Quad", or an Eta Aquarid as
simply as an "ETA".
GeoZay

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