he icy moons of the outer Solar
System are attracting more and
more attention from planetary
scientists. Decades of studies have shown
that there is a lot of liquid water locked
away inside the outer moons. On Earth,
pretty much anywhere you find water, you
find life – so could be the same be true of
the outer moons?
“In terms of potential habitats, I think
most [astronomers] are fairly sure that there
are places inside many of these moons
where, if you put the right kind of organism
there, they would survive. So we’ve got
habitats, we just don’t know whether they
are inhabited by organisms,” says David
Rothery, a planetary scientist from the OpenUniversity, UK, who surveyed the moons of
the Solar System for his book Moons: A
Very Short Introduction.Looking for life beyond Earth is no mere
exercise in intellectual curiosity, either.
Should we ever find any such life, it
should tell us more about how life began
here on our own planet.
At present, no one knows exactly what
conditions are needed to f lick the switch from
mere chemistry to biology. Did this process
occur readily, or was it the result of a chain of
unlikely events? That’s something that
finding life elsewhere would help us answer.“If we can find places in the Solar
System where life began independently
from life on Earth, then... wow! That is
pretty compelling evidence that if life can
start, it will start,” says Rothery.
Life needs a power source. Once, we
thought that the only suitable source of
such power in the Solar System was the
Sun, which meant that life had to exist on
a planet’s surface. Hence the interest in
Mars, which seems to be the most Earth-
like of the other planets. However, a
discovery on the f loor of the Pacific
Ocean in 1977 changed all that.
Researchers from the Scripps Institute of
Oceanography in California were exploring
around the volcanic ridge known as the EastT
THERE’S BEEN A LOT OF TALK RECENTLY ABOUT
LOOKING FOR EXTRATERRESTRIAL LIFE. WE’RE
BOMBARDED WITH STORIES ABOUT LIFE ON MARS
OR HABITABLE WORLDS CIRCLING OTHER STARS.
BUT COULD THIS BE BLINDING US TO BETTER PLACES
TO LOOK FOR LIFE? STUART CLARK INVESTIGATES
ARE WE LOOKING FOR ALIEN
LIFE IN THE WRONG PLACE?
PHOTO: GETTYSCIENCE