Have we descended from Mars?

Researchers are working on the proposed instrument called `Search for Extra-Terrestrial Genomes`.

Last Updated: Mar 24, 2011, 14:18 PM IST

Boston: A team of researchers at Harvard
and the Massachusetts Institute of Technology are developing a
device that will study whether life on Earth descended from
organisms that were originated on Mars and carried to our
planet aboard meteorites - a theory that would make all humans
of Martian-descent.

MIT research scientist Christopher Carr, postdoctoral
associate Clarissa Lui, head of MIT`s Department of Earth,
Atmospheric and Planetary Sciences Maria Zuber and Harvard
University molecular biologist Gary Ruvkuna are working on the
proposed instrument called the `Search for Extra-Terrestrial
Genomes` (SETG).

The MIT researchers` device, which could be carried on
future missions to Mars, would take samples of Martian soil
and isolate any living microbes that might be present or
microbial remnants, which can be preserved for about up to a
million years and still contain viable DNA.

They would separate out the genetic material in order
to use standard biochemical techniques to analyse their
genetic sequences. The team would search for DNA or RNA in the
Martian soil, separating any possible organisms using the same
techniques used for forensic DNA testing on Earth.

Biochemical markers would be used to search for signs
of particular, genetic sequences that are nearly universal
among all known life forms.

SETG would take a sample of Martian soil from below
the surface on Mars, dredged up by a rover equipped with a
deep drill.

"It is a long shot," Carr said in a MIT statement. "But if we go to Mars and find life that is related to us, we could have originated on Mars. Or if it started here,
it could have been transferred to Mars."

Either way, "we could be related to life on Mars. So
we should at least be looking for life on Mars that is related
to us."

Orbital dynamics show that it is about 100 times
easier for rocks to travel from Mars to Earth than the other
way. If life got started on Mars first, microbes could have
been carried here and "we might all be its descendants."

"If we are descendants from Mars, there might be
important lessons to be learned about our own biological
origins by studying biochemistry on our neighbour planet,
where biological traces erased long ago on Earth might have
been preserved in the Martian deep freeze," the statement
said.

The researchers estimate that it could take two more
years to complete the design and testing of a prototype SETG
device.

A future mission with a lander or rover equipped with
a drill could potentially carry this life-detection
instrument. The team is basing its idea on several
well-established facts.

In the early days of the solar system, the climates on
Mars and Earth were much more similar than they are now, so
life that took hold on one planet could presumably have
survived on the other.

Further, an estimated one billion tons of rock have
travelled from Mars to Earth, blasted loose by asteroid
impacts and then travelling through interplanetary space
before striking Earth`s surface.

Microbes have been shown to be capable of surviving
the initial shock of such an impact, and there is some
evidence they could also survive the thousands of years of
transit through space before arriving at another planet.

"So the various steps needed for life to have started
on one planet and spread to another are all plausible," the
MIT statement said.

Recent Mars orbiter and rover missions have shown that
Mars once had abundant water and many of the conditions
thought to be needed to support life.

While the surface of Mars today is too cold and dry to
support known life forms, there is evidence that liquid water
may exist not far below the surface.

"On Mars today, the best place to look for life is in
the subsurface," Carr added.

PTI