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SAM stands for the Sample Analysis at
Mars instrument suite. It's really one of the most complex and analytical
chemistry laboratories ever sent to the surface of the Red Planet. It's been
miniaturized to fit right into the body of the Mars Science Laboratory
Curiosity Rover. One of the major goals of the Mars Science Laboratory mission
is to search for habitable environments in Gale Crater. And by by habitable
environments, what I'm talking about are environments that could have supported life.
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So there are several pieces of big news that SAM has found.
The first is the discovery of methane. Now methane has been
found previously in the Martian atmosphere by both Earth-based telescopes
and space-borne orbiters. But this is the first time that we've actually
seen a sharp increase and decrease in the abundance of methane in the atmosphere
in Gale Crater. What this really means is that present day Mars is an active
environment. Now at this point we don't know the origin of this methane.
It could be biological, from maybe methanogenic bacteria
deep in the subsurface releasing methane. But there are non-biological explanations
as well - such as water-rock interactions in the subsurface that could also
produce the methane signals that we're seeing. The second exciting discovery
from SAM is the detection of Martian organic compounds.
We found several different types of organic molecules including chlorinated alkanes
and chlorobenzene - compounds that are not common on Earth - in a mudstone
that was deposited in an ancient lakebed environment in Gale Crater.
This is a really exciting discovery because we've been looking for organic compounds for decades
on the surface of Mars. And this is the first time that we've actually found
Martian organic material in the surface. Now, at
this point we don't have enough evidence to tell us whether or not the organics
we're finding are biological or non-biological in origin. There are
several viable non-biological explanations, including this organic
material could have come down from space - from meteorites or comets. Or,
organics can be formed by geological reactions in the rock itself.
Now what's exciting about this discovery is it gives us new hope
in the search for chemical evidence of life. We've found the organic material,
now the next step is trying to figure out what its origin is.
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So in addition to the measurements made by SAM on Mars, we've had
to do hundreds of laboratory experiments back on Earth to simulate
the conditions on the surface of the Red Planet in order to convince ourselves
that the organic material we were detecting by SAM was really Martian in origin
and not something that we had brought with us to Mars.
(Music)
So although at this point in the mission we can't conclude that there was definitively life
on Mars, the SAM discoveries have really shown us that all of the basic
ingredients for life were there - including complex organic compounds,
the building blocks of life. Now with the detection of organics in Gale
Crater, the probability that Gale Crater Lake could have supported life
goes up.
(Beeping)