[meteorite-list] OT: more Columbia debris trajectory analysis

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:18:25 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4E6E9_at_US-Torrance.mail.saic.com>

Hi Ron,

> OK, let's assume then that the debris took a slight deviation
> from the shuttle's flight path towards the south when it separated
> from the shuttle. Could that be enough to account for the
> additional distance to Joshua Tree?

My intuition says no based on analysis below.

> The debris field in Texas/Louisiana is at least 380 miles by
> 230 miles, and that was at a lower altitude over Texas.

The altitude was about 61 km over north central Texas, so it
was still pretty high. A 230-mile cross-track spread in debris
might seem like a lot, but given that the main break-up was
beginning at least 600 miles to the west-northwest (and initial
pieces were separating at least 1500 miles to the WNW), a
downstream spread of +/- 115 miles represents a dispersion
of +/- 11 degrees for the main breakup, and only +/- 4.4 degrees
from California. By contrast, the necessary angular diversion
for a fragment breaking off at 8:53am EST (while Columbia was
just off the coast of California) is over 30 (!) degrees to
Joshua Tree, CA.

What this means is that the only way to get debris to Joshua
Tree is if it separates from Columbia well before it reaches
the California coastline -- at least two or three minutes
earlier (8:51, 8:50). But this is a problem, because the
further you go back in time, the higher the Shuttle is, and
the thinner the atmosphere. So the possible deviation from
a purely ballistic trajectory is lower.
 
> Incidently, from the desciption of the item found in Joshua
> Tree, it didn't sound like what was found there was a
> shuttle tile:
> 4-inch square object described as looking like a piece
> of exposed film. It has foil-like material on one side
> and apparent burn marks.

This morning's news said (perhaps mistakenly) that it was
a metallic object -- like "a piece of a camera." If it's
just a film-like object, then its terminal velocity could
be quite a bit slower -- maybe only 5 mph -- taking
correspondingly longer to fall through the jet stream,
and thus being carried further. My 400-kph jet stream was
being pretty generous, though. You'd still need to shed
this debris over the Pacific Ocean to have any hope of it
showing up so far south.

Cheers,
Rob
Received on Wed 05 Feb 2003 10:47:25 PM PST