Have we descended from Mars?

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.