[meteorite-list] OT: Joshua Tree, maybe - NOT

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:18:25 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4E6E6_at_US-Torrance.mail.saic.com>

Hi Ron and List,

This is off-topic for Meteorite Central so delete if the question
of Columbia's debris field does not interest you.

Ron posted:

"Well, there is definite significent drag on the shuttle well
before it reaches California. The shuttle is glowing (per the
photos), and the astronauts have already embarked on their S-turns
maneuvers to slow down the shuttle."

Agreed. The Shuttle is decelerating. Broken away tiles would
decelerate even faster.

> Eyewitnesses in both California and Arizona have observed
> material coming off the shuttle, and then falling way
> behind quickly. Have you taken the jetstreams into account?

YES. Have you taken the ALTITUDE of the jet stream into
consideration? The top of the jet stream is at an altitude of
about 14 km.

> Joshua Tree is directly south of western Nevada. I've looked
> at a jetstream map, and it showed all jetstreams from Nevada
> are heading south, towards southern California.

I've looked at the same polar jet stream map (for those interested,
check out <http://squall.sfsu.edu/scripts/jetstream_modelsml.html>).
Before the jet stream can start giving Shuttle tiles a ride, those
tiles have to get down there. The jet stream is only about
5 km thick; while the tiles are light, gravity still brings
them down. I don't know what the freefall terminal velocity
is for a tumbling tile, but I'd think it's at least 30 mph.
At even that slow speed, a tile would only spend a little over
6 minutes in the jet stream. The maximum jet stream velocity
is about 400 km/hour during which time the tile could
travel a little over 41 km. Joshua Tree is over 450 km away
from the groundtrack, so you see why it really doesn't make
any sense to consider it for debris heavier than a few
ounces.

As I wrote another individual earlier today, if NASA has decided
to check out the Joshua Tree debris, that is of course their choice,
but in my opinion it is a waste of their limited resources. I
realize they're desperate for clues, particularly the important
ones that would be found west of Texas, but where do they draw the
line? Certainly if someone said they found Columbia debris in
Minnesota, NASA wouldn't be expending personnel and $$$ checking
it out. But from an aerodynamics and probability standpoint,
the southern California and Minnesota locations are really no
different.

NASA would do themselves a big favor if they would release a
map showing the POSSIBLE corridor where debris might be found.
Color code it with 1-, 2- and 3-sigma excursions. I'm half-
inclined to generate such a map myself, if only to counteract
the media's misplaced emphasis on extremely unlikely finds.

By now, I should think that we in the meteorite world would
be all too familiar with the "false alarm rate" of the general
public when it comes to science-related issues. I know most
everyone means well and wants to help in any way that they
can to solve the mystery of this tragedy. Perhaps the media
will take a more proactive stance and at least inform people
of the most likely regions where debris might be found.

Best,
Rob
Received on Wed 05 Feb 2003 09:13:23 PM PST