(news.discovery.com)Our search for life beyond Earth could take us down the road to a shocking look into the mirror -- a climax straight out of a Twilight Zone plot.

A team of researchers at MIT is proposing to apply forensic science testing on the Martian surface. Specifically, the task would be to do DNA and RNA sequencing on Martian microbes (if they exist) to seen if they share a common genetic origin with us.
This addresses the novel question of panspermia -- that we are descended from Mars life that migrated to Earth. Such testing could also offer key insights into how serious a risk Martian microbes would present to human colonists.

The MIT team led by Christopher Carr and Maria Zuber (head of MIT's Department of Earth, Atmospheric and Planetary Sciences) and Gary Ruvkun, a molecular biologist at the Massachusetts General Hospital and Harvard University, are proposing to build an instrument to send to Mars and test for extraterrestrial genomes.

Despite the numerous landers and rovers we've sent already, the only surface biology experiments were carried out in a bold but premature effort in 1976 aboard the trailblazing NASA Viking landers. The confusing results from these tests remain controversial and ambiguous today.

Invaders From Space

Such a mini-forensics lab would test the hypothesis that life on Earth may have come from Mars. The Martians didn't arrive in spaceships, but microbes hitchhiking aboard meteorites blasted off Mars by ancient impacts. After millions of years in space, the meteorites would fall onto Earth and the microbes adapt to a new home.

Experiments done at Harvard University show that bacterial spores can survive riding alone on a simulated meteorite impact on Earth -- even without airbags. There is also data that microbes could also hibernate for the thousands of years in the vacuum of space before falling to Earth.

An estimated one billion tons of rock have already traveled from Mars to Earth. The controversy continues today as to whether we already have alien biological evidence for Martians aboard the Allan Hills Martian meteorite, ALH 84001.

But panspermia is not a two-way street because it is much harder to get enough asteroid impact energy to launch microbe-laden Earth rocks toward Mars (because Earth has a deeper gravitational well for the rocks to blast out of). What’s more, Mars probably became more suitable to the origin of life before the slower cooling, and more heavily bombarded, Earth did. There is compelling evidence for the existence of a great Martian ocean that once existed 3-4 billion years ago. As on Earth, life would be expected to have originated in such an ocean.

Digging Up Life
The Mars genome experiment would need to be aboard a lander or rover capable of drilling into the Martian soil and retrieving a sample from beneath the surface. Life could hang out just below the surface where there could be water and protection from solar UV radiation. This is suspected to be the case at the Phoenix Polar Lander site in the Martian arctic.
The miniature lab would isolate any living microbes that might be present, or even microbial remnants. The device would autonomously separate out the genetic material and then amplify the DNA or RNA in microbes by using the same techniques used for forensic DNA testing on Earth. It would then use biochemical markers to search for genetic sequences.
The shocker would be that the genetic sequences matched those found in Earth microbes. The conclusion: "we are Martians!"
But wait, how could we be sure they weren’t really Earth microbes that hitched a ride to Mars aboard a U.S. or Soviet spacecraft, and then colonized the Red Planet?
"There may indeed be some confusion," says astrobiologist Chris McKay of NASA's Ames Research Center in Mountain View, California. "If we find organisms on Mars that are particularly cold adapted we might conclude that they did not come from the Jet Propulsion Lab in Pasadena, California (where Mars landers were built) or the Kennedy Space Center in Florida."
This type testing is critical say the researchers because an alien microbe that is similar to Earth organisms is much more likely to be infectious to terrestrial life forms, than would a form of life that independently evolved.
This could give us pause about sending humans to a germ-laden alien world. It would be an ironic twist on the H.G. Wells classic 1898 novel "The War of the Worlds," where invading Martians succumb to the common cold from Earth microbes.
See, Wells' Martian warriors should have done genome testing first.

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