[meteorite-list] Life's Rocky Road Between Worlds

From: David Weir <dgweir_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:12 2004
Message-ID: <3B26775F.322E796D_at_earthlink.net>

Ron replied:

> The main difference is the amount of time the samples spend in space enroute
> to Earth. For the typical Mars meteorite, it would have been in space for 15
> to 30 millions years before it landed on Earth. For a sample returned by
> spacecraft, the sample would only spend a few months in space enclosed in a
> container. Any Mars organisms, if present, would have a much higher likelihood
> of surviving the trip from Mars to Earth in a spacecraft than in a Mars meteorite.

I included the particular quote from the article in part to dispell that
very argument. They have already calculated the 7% microbe survival rate
in the 150 kg of hospitable rocks per year to derive their equivalent 10
kg per year number. So that is not a sufficient reason to worry.

Quoting again:

> > "The long term average transfer rate of 150kg of hospitable rocks per
> > year,
> > with 7% of resident microbes surviving (if any were present in the rocks
> > at
> > the time of launch), is equivalent to a series of space missions that
> > return samples of about 10 kg of Martian rocks each year under protected
> > conditions that are favourable to the survival of any life within the
> > rocks."

Ron also writes:

> To date, we haven't found any surviving microprobes in any of the Mars meteorites.
> ALH84001 only involved potential microfossils.

Okay, that's further reason not to worry. You're helping my case now.

David
Received on Tue 12 Jun 2001 04:11:11 PM PDT