A lot of people talk about the possibility of life on Mars. Steve Squyres
is doing something about it. Squyres, a Cornell planetary geoscientist,
is the leader of science teams for two upcoming missions to Mars.
"Finding evidence of life on Mars would radically change the way we think
about life on our own planet," says Squyres. His voice lowers and he
whispers, almost conspiratorially, "It would change everything."
Squyres' experiments, part of NASA's Mars Surveyor program, are called
APEX and Athena. Each is designed in part to investigate whether life has
ever existed on the red planet.
"We have devised a strategy to tell us a lot about Mars, and at the same
time that maximizes the chance of finding evidence of ancient life," says
If there is any place beyond Earth where life seems likely to have taken
root, it's Mars. With volcanoes indicating a once-active source of
energy deep within the planet, and ancient valleys almost certainly
carved by running water, Mars may have once looked much more like our own
planet. Scientists wonder if Mars, like Earth, could also have served as
an incubator for life.
"We know that life came into being on Earth. But no one understands how
non-living turns into living. Yet it happened, and no one has been able
to duplicate it," explains Squyres.
The geologic record of the earliest forms of life on Earth is gone. Even
in some of the very oldest rocks on our planet, scientists have found
complex microbial fossils, with forms too complex to have been the first
living things on Earth. Erosion and melting of the Earth's crustal rocks
have obliterated any record of "first life."
"On Mars, it isn't a problem to find rocks dating back nearly to the
birth of the planet," says Squyres. Since Mars is so much smaller than
Earth, it has cooled off more quickly, limiting the kind of large-scale
rock recycling found on Earth. Plus, with a thinner atmosphere, Mars has
experienced less erosion. According to Squyres, the oldest rocks on Mars
should provide a "snapshot" of the early geologic history of the planet.
If life ever did exist on Mars, Squyres believes that evidence of it
could still lie hidden in a geologic record that's located more than 128
million miles away from home.
View from Lander 1 Site. Big Joe, the large rock just left of center, is about 2 m (7 ft) wide. This rock may be a fragment of a lava flow that was later ejected by an impact crater. The red color of the rocks and soil is due to an abundance of oxidized iron in the eroded material.
The trick is getting that geologic record back to Earth for study. So
far all the missions to Mars have performed experiments on rock samples
located around the landing site.
"Doing that kind of experiment on Earth wouldn't necessarily yield signs
of life either," comments Squyres. "There are many rocks on Earth that
contain no fossils. What we need is to send a geologist to Mars to pick
and choose rocks most likely to contain evidence of life. The Athena
Rover is really a robotic field geologist."
The FIDO Rover, a prototype of the 2003 Athena Rover.
The 2001 APEX experiment and the 2003 Athena Rover will be the first
steps in the quest to return rock samples from another planet.
NASA's 2001 and 2003 Mars missions will each put a lander on Mars, and
each will carry a rover. The 2001 rover, known as Marie Curie, will stick
close to the lander vehicle and help scientists decide which kinds of
rocks they would like to study on Earth.
The 2003 Athena Rover, which will have a range of as much as 10
kilometers, will actually collect rock samples and place them into
soccer-ball sized containers, which will in turn be blasted into orbit
around Mars. The orbiting rock collections will be picked up and
returned to Earth by a mission to be launched in 2005.
Scientists have long awaited extraterrestrial rocks to study. And Squyres
is no different. Still, he is quick to issue a caution: "The probability
of us coming back with fossils is probably slim."
If life ever existed on Mars, Steve Squyres is determined to find it.
"When I was a kid, I was fascinated by exploration of all sorts.
The deep sea, the polar regions. Captain Cook, and the other explorers.
I originally went into geology to combine science and exploration. Going
to Mars is the ultimate kind of science exploration -- because we just
don't know what we're going to find."