[meteorite-list] St. Robert entry angle

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:52:13 2004
Message-ID: <200208132102.OAA21070_at_zagami.jpl.nasa.gov>

>
> I saw the discrepancy and assumed one was an early estimate.
> The TKW on St. Robert (ordinary chondrite) was 25.4 kg according to
> the Catalogue of Meteorites. Note the fairly slow estimated entry
> velocity:
>
> "A statistical evaluation of the likely heliocentric orbits for the
> body prior to collision with the Earth, coupled with theoretical
> modeling of the entry, suggests an entry velocity in the range of
> 12.7-13.3 km/s ..."

There are velocity measurements. There is velocity relative to Earth
prior to accerleration caused by Earth's gravity (V infinitiy), and the
velocity at atmospheric entry which include's Earth's gravity field (V impact).

There is an asteroid on our Risk page, 1994 UG, with a V impact
of 12.8 km/second, similar to St. Robert's:

http://neo.jpl.nasa.gov/risk/1994ug.html

What is interesting about 1994 UG, is that is has an orbit that goes out to
the orbit of Mars:

http://neo.jpl.nasa.gov/cgi-bin/db?name=1994+UG

>The minimum possible is around 11 km/sec.

That would be from an object that has on orbit very similar to Earth's orbit,
like asteroid 2000 SG344 which has a V impact of 11.23 km/second:

http://neo.jpl.nasa.gov/cgi-bin/db?name=2000+SG344

Ron Baalke
Received on Tue 13 Aug 2002 05:02:31 PM PDT