Countless
science fictions books and films have shown Martian armies attacking the Earth,
marching across our planet and enslaving or eradicating any humans they come
across. Obviously this hasn't happened ... yet!
In
fact, Earth is preparing for an invasion of Mars, but not in the conventional
sense. Right now a flotilla of space probes are assembling to storm our
neighboring planet, but rather than being armed with heat rays, they're kitted
out with the latest in scientific equipment.
Their
mission? To learn all they can about the red planet, and perhaps even answer
the question of whether it harbors alien life.
It's
certainly an exciting time for Mars exploration. The rovers Spirit and Opportunity are still scouting out the surface and sending back incredible images. The Phoenix
Lander is on its way to Mars right now, and should arrive at the Martian
north pole on May 25. After this will come NASA's Mars
Science Laboratory, a large rover that will launch next year and arrive in
2010. Finally, the European Space Agency's ExoMars mission is expected to hit the
ground in 2014.
It's
certainly an attack in force, and two generals planning this assault are
Michael Meyer, a lead scientist for NASA's Mars Exploration Program and Luann
Becker, a University of California, Santa Barbara geochemist.
To
test for alien life the missions will look for organic chemicals — strong
clues that living organisms are there. Becker has developed the Mars Organic
Molecule Analyzer, or MOMA. She explains, "MOMA is like a Star Trek
tricorder because we can use it to cover the full gamut of measurements that
will answer the question of life. Then we'll be able to address the difficult
question of whether something interesting is there."
This
kind of thing has been tried before with the Viking missions of the 1970s,
although the results were frustratingly ambiguous. Says Meyer, "Part of
the controversy was with Viking's Labeled
Release Experiment. The concept was that if we added organics and water to
the Martian soil, all the Martian organisms in that soil would go to town
eating the organic matter. The organics would in the process be broken down
into carbon dioxide gas, and we could measure that."
Basically,
samples were warmed up and given food-like chemicals and then watched to see if
any microbes reacted. Becker laments, "Viking was an excellent experiment
if you think about the strategy behind it: going to Mars and heating a sample, something
we do everyday in our laboratory. [But] we got ambiguous results — something
might be there, but it might not be there. Anytime you get an ambiguous result,
that's considered a non-result."
The same idea of hunting for organic materials is used for modern missions. Half
the battle is knowing where to look by deciding which areas are most likely to
give interesting results. "Location, location, location," says Becker.
"That really is key. We're going to have to use every bit of information
we get from the satellites currently flying."
NASA's
Mars
Reconnaissance Orbiter is taking high resolution photos of the Martian
surface, providing valuable intelligence about landing sites. However, a "shotgun
approach" is in the cards — scattering the various machines over different
areas to sample a range of locations. Says Meyer, "We are sending missions
to three different places. Phoenix is going to dig into the ice near the north
pole. Mars Science Laboratory has a little drill, so it's going to go to
wherever there's exposed bedrock and rocks lying around. ExoMars has a big
drill, so it's going to go deeper down into the surface."
With
all these missions on the way, hopes are high that we'll soon conquer Mars by
uncovering its most guarded secrets. However, past attempts like Viking have
proven that Mars is a difficult enemy to overcome. Still, lessons have been
learned and many are optimistic. Victory could well be within our sights.
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