Why can't it be possible? GRS on Mars Odyssey has shown there are near equatorial spots on Mars with high hydrogen content, including Gusev:

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From: Robert Clark (rgregoryclark@yahoo.com)
Subject: Re: Los Alamos Release New Maps Of Mars Water
Newsgroups: sci.astro, alt.sci.planetary, alt.astronomy, alt.life-mars
Date: 2003-07-26 10:46:30 PST

news_naught <news_0@naught.net> wrote in message news:<d8lUa.5$hk.547@dfw-read.news.verio.net>...
> Ron Baalke wrote:
> > http://www.lanl.gov/worldview/news/releases/archive/03-101.shtml
> >
> > Los Alamos releases new maps of Mars water
> >
> Water, water everywhere; except Gusev crater so
> why is the rover going there?

Gusev is at about -15 lat. and 185 W long. As you can see in the
first map on this page, that lies within the area of high hydrogen
content near the equator:

Photos: Water on Mars
http://www.lanl.gov/worldview/news/photos/mars.shtml

This is also discussed in this report of Natalie Cabrol et.al. about
the MER mission:

Synthesis of the Testable Hypotheses for Gusev.
http://marsoweb.nas.nasa.gov/mer2003/doc/arcadia_03/talks/Cabrol/cabrol.pdf

Bob Clark
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