Page 52 - (DK) Eyewitness - Mars

Is there life on Mars?

Questions about Martian life began when
early astronomers thought the planet was
much like Earth. Later observers imagined
they saw canals and vegetation in their
telescopes. A few said Martians might be more
advanced than humans. Then orbiters and
robotic rovers found Mars to be a frozen desert
with no living organisms. Scientists began to
look for signs of past life, especially where SPOTS ON POLAR ICE
water once flowed. Their instruments These blotches on polar ice in
springtime are thought to be caused
discovered ice, and their studies delved into by frost withdrawing. A few
Martian rocks on the planet and Martian scientists, however, think certain of
these patterns could be caused by
meteorites on Earth. Since microscopic life- living microorganisms that change
their forms with warmer weather.
forms exist in Earth’s most extreme regions, then Bacteria living in Antarctic ice create
microorganisms might also exist on Mars. The planet similar patterns. On Mars some
patterns change even in places
has “hot spots” that might be geothermal vents. These, where frost does not withdraw.
some scientists say, may be among the best places to
look for Martian life.

SNOW ALGAE ON EARTH
Tiny plantlike organisms called algae
thrive in places on Earth where no
other living things can exist. Some are
in hot springs, where water boils.
Others, like this snow algae,
Chlamydomonas nivalis, survive in
bitterly cold conditions comparable to
the Martian environment. Researchers
believe such primitive organisms might
be found on Mars.

REULL VALLIS GULLIES
The winding channel of Reull
Vallis, imaged by Mars Express
orbiter in 2004, empties into
the Hellas basin. If water ever
flowed through this canyon,
then living creatures may also
have been here. Fossil
microorganisms might be
present in the soil at the
bottom of the canyon, in
cracked rocks there, or in ice
deposits beneath the surface.

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