[meteorite-list] Impact Event On Mars In 1951?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:13:09 2004
Message-ID: <200304241522.IAA03442_at_zagami.jpl.nasa.gov>

--Abstract Published in Meteoritics and Planetary Sciences
(MAPS) 37(7), supplement, p.A122, 2002.

A SMALL IMPACT EVENT ON MARS IN 1951
M.C.L.Rocca
Mendoza 2779-16A,
Ciudad de Buenos Aires,
Argentina (1428DKU), maxrocca_at_hotmail.com

Introduction: Any meteoroid impacting into the thin atmosphere of
Mars penetrates deeper than into the denser Earth atmosphere. As a rule,
meteoroids bigger than 1 meter in size hit the martian surface.
Objects with the size of about 0.1 - 1.0 meters explode high in the
martian atmosphere creating intense blast waves and light flashes.
Those superbolide events have a luminous efficiency higher than at the
Earth [1], [2]. As part of a search in old scientific publications one
superbolide-impact event on Mars has come to light. It was reported by
the japanese astronomer Tsuneo Saheki, at Osaka Planetarium. He used a
8-inch reflector, at 400x. The event occurred on December 8, 1951.

"At 21:00 I saw a sharp , bright, glaring spot suddenly appear on
Tithonius Lacus. It was as brillant as a 6 th. magnitude star -
decidedly brighter than the north polar cap - and shone with
scintillation for about five minutes. Fadding rapidly, by 21:05 it
looked like a whitish cloudlet, as large as Tithonius Lacus. At 21:10 it
was barely visible as a very faint and large white spot, and by 21:40
this part of the martian surface had returned to its normal state" [3].

The four drawings he published are very interesting. The first shows a
radiate structure wich may be explained as ballistic ejecta from the
impact site. Careful searches in old journals may offer puzzling new
examples of superbolide and impact events on Mars.

References:
[1] Kosarev I.B. et al. (2000): MAPS 35 , supplement, pp. A91.
[2] Adolfsson L.G., Gustafson B.A.S. and Murray C.D. (1996): Icarus
    119, pp.144 -152.
[3] Saheki T. (1955) Sky & Telescope 14, pp. 144 -146.
Received on Thu 24 Apr 2003 11:22:34 AM PDT