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ABSTRACT: Mars is the planet of most interest to Earthfolk
because it is the planet most like Earth, and
is easy
to reach. Because it is cold, dusty, and dry,
scientists were very surprised in the 1970s
to discover it is laced with dry riverbeds.
Observations from spacecraft and from Martian
meteorites (rocks blown of Mars, now in our
museums) allow study of the Martian atmosphere,
which is very thin. Trace gases reveal, however,
that the primordial atmosphere was much thicker.
Therefore, early Mars seems to have been relatively
similar to primordial Earth. Spirit and Opportunity
landing sites were chosen as spots where water
may have ponded in the past.
Because of these similarities, the quest to determine if life ever started
on Mars is the prime driver of international
missions. This is the perfect scientific question
because either answer is profound. If we find
life did start, it proves for the first time
that we are not alone in the universe. If it
never started, in spite of a relatively water-rich
environment, it may show we are more alone
than we thought, or that something is wrong
with our theories of life. A profound results,
either way!
Current work on Mars is showing that it is a much more active planet than
many had thought. Counts of impact craters,
as well as dates from Mars meteorites, reveal
widespread lava flows formed within the last
few hundred million years. The most recent
of several dozen dated Mars rocks is basaltic
lava only 170 My old. Massive amounts of underground
ice appear to exist. Discoveries in 2001 revealed
very recent gullies carved by water runoff
on hillsides, and glacier-like features have
been found. It is plausible that modern geothermal
activity may melt the base of the underground
ice layers, creating underground aquifers of
liquid water, which could be habitats for microbial
life. Microbes have been reported on Earth
that can go dormant for 100 My or more.
In
preparation of my book, A Traveler's Guide
to Mars, I processed numbers of Martian orbital
and surface photos, and sought analogous places
on Earth. Gullied hillsides in Iceland, volcanic
deserts in Hawaii, lava flows in Mexico, playas
at Death Valley, and eroded gullies in southern
California are examples. Astronomical painters,
visiting such sites, create Martian landscapes
are beginning to create a "Martian art." |
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