New Study Claims Mars Dry for 4 Billion Years

Today on the Web there was an item at space.com by Senior Science
Writer Robert Roy Britt, announcing the results of a study due to
appear in the July 22 issue of the journal Science, in which Caltech
graduate student David Shuster and Asst. Prof. Benjamin Weiss suggest
that Mars hasn't had "large areas of freestanding water for four
billion years", but don't rule out "pockets of isolated water in
geothermal springs for periods of time".

The study is based upon argon decay analysis of the remaining argon
content of seven meteorites "known to have arrived from Mars after
millions of years in space". The study relies on a formula for argon
decay that varies with temperature. "Any way we look at it, these
rocks have been very cold for a very long time," says Shuster.

As of this posting, the 7/22/05 issue of Science is not yet available
at its online site www.sciencemag.org .

Offhand, there seem to be a number of assumptions to be justified.
Whether the study does so successfully remains to be seen, though the
fact that these represent elementary issues suggests that they wouldn't
be overlooked.

First, how is it known that the rocks weren't in space for merely
"millions of years" but perhaps for billions of years? If they were
thrust into space as the result of a cataclysmic event four billion
years ago, and have been floating in space during the intervening time,
wouldn't the study be invalidated by the fact that space is cold?

Second, what were the climate patterns on Mars up until the time these
rocks became spaceborn? Could they have originated in a part of Mars
that was "very cold" without implicating the same climate for all the
rest of the planet?

Third, what were the original argon levels in these rocks, and how is
this known? If volcanic, other geological, atmospheric, or even
biological processes resulted in a different argon ratio than expected,
could this alter the validity of the study?

Other questions come to mind, but these are the primary ones that
occured to me while reading the media coverage of the study.

Mark Adkins
msadkins04@xxxxxxxxx

.

Relevant Pages

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