Mars rock. (NASA)
A pebble, with a unique history, may contain
the first evidence of life beyond the plant Earth. Sample ALH84001
started its existence when it crystallized out of hot magma
on the planet Mars some 4.5 billion years ago. Half a billion
years later it became a space traveler when an asteroid or comet
struck the planet and sent chunks of Martian crust flying into
space. Caught by the gravity of the Sun it drifted toward the
center of the solar system until 13,000 years ago when it collided
with Earth and landed in Antarctica. In 1984 it was picked
up by scientists who identified it's place of origin by comparing
bubbles trapped in the rock with the known mixture of gases
What makes this little rock so interesting isn't
just its interplanetary wanderings. It's the tiny tubular shapes
found inside. They resemble fossilized bacteria (below-left,
NASA). Concentrated around the shapes are three different
chemical compounds that may well have been the by-product of
the ancient microbe activity. NASA scientists concluded that
a "reasonable interpretation" of the facts was that there once
was, and perhaps still is, life on Mars.
Other scientists disagree pointing out that all
the chemicals could have been formed by other natural processes.
They also note the shapes are a hundred times smaller than the
smallest known Earth bacteria.
Supporters of the life theory claim that with
all the compounds concentrated in such a small space, other
explanations, besides life, are unlikely. As for the size they
point to the work of Robert Folk, of the University of Texas,
who claims to have found almost identically small Earth microbes
living in travertein and limestone rock. Folk's tiny bacteria
have yet to be fully accepted within the scientific community,
Until scientists can figure out how to slice the
shapes open, not an easy task because they are so small, and
find something inside that resembles the structure of a cell,
the question, of life on Mars, will be open for debate.
The rock was originally located deep under the
Martian surface and if it turns out it truly bears microfossils
then it seems a real possibility that life may, even now, thrive
underground on Mars. Just a few years ago scientists might have
laughed at the idea living creatures could subsist without getting
energy from the sun, but recently bacteria has been found living
almost a mile below the surface of the Earth surviving on nothing
but water and hydrogen from the surrounding basalt rock. Similar
underground conditions could exist on Mars.
In Romania a whole ecosystem, including spiders,
scorpions, leeches and millipedes, has been found in a cave
that was cut off from the surface of the Earth 5.5 million years
ago. The entire thing was fueled by bacteria that eats the surrounding
rock. If the same thing has happened on Mars we may find that
more complex creatures than just bacteria may thrive on that
planet, if we can just look below the surface.
Copyright Lee Krystek
1996. All Rights Reserved.