Doublet craters in the inner solar system

Doublet Craters in the Inner Solar System
compiled by Wm. Robert Johnston
last updated 16 March 2002

Doublet craters--slightly separated pairs of craters formed near-simultaneously--represent additional evidence of binary asteroids. Surveys of craters over 10-20 km in diameter indicate that doublet craters comprise about 2% of craters on Mars, 10-15% on the Earth, and 2-14% on Venus. (Note that these are distinct from doublet craters formed by the grazing impact of a single object which "skips" on impact, examples of which include Messier A and B on the Moon and a series of craters in Argentina.)

Cook, Melosh and Bottke suggested a doublet fraction of 2.2% for Venus based on an initial crater review and a 14% when including radar-dark "splotches" believed formed by impacting objects too small to reach the surface intact.

Three examples of doublet craters exist on Earth; these have been found to have similar geologic ages.

For Mars, Melosh, Ingram, and Bottke identified 3 likely doublets in a sample of 133 craters, giving a fraction of 2.3%.

Some doublet craters

planet	name	lat./long.	diameter (km)	separation (km)	hypothetical component sizes(km)
Earth	West Clearwater Lake East Clearwater Lake	(Canada)	32 22	28.5	3.3 2.1
	Ries Steinheim		24 3.4	46	2.3 0.2
	Kamensk Gusev		25 3	15	2.4 0.16
Mars		71.2°N, 10.3°W 71.1°N, 10.3°W	10 8	5	0.8 0.6
		70.4°N, 18.6°W 70.5°N, 18.7°W	10 5.2	8	0.8 0.3
		69.9°N, 120.8°W 69.8°N, 120.9°W	10 6	5	0.8 0.4

Sources:

Cook, C. M., H. J. Melosh, and W. F. Bottke, 1996, Doublet craters on Venus, Icarus.
Melosh, H. J., J. Ingram, and W. F. Bottke, 1996, The abundance of doublet craters on Mars, LPS XXVII, 863.
Melosh, H. J., and J. Stansberry, 1991, Doublet craters and the tidal disruption of binary asteroids, LPI.

© 2002 by Wm. Robert Johnston.
Last modified 16 March 2002.
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