We Could Be Martians

A century ago, scientists ostracized a famous pioneering Arizona astronomer, Percival Lowell, for theorizing that features observed on the surface of Mars, including those he interpreted as canals, showed that Mars once sustained intelligent life.

Despite intense scrutiny by today's powerful advanced telescopes – most notably the Mars-orbiting High Resolution Imaging Science Experiment camera operated from The University of Arizona that could see a human standing on the Martian surface – there's still no evidence for advanced life forms on Mars.

But Lowell may have been right about there being life on Mars before there was life on Earth by a mechanism he didn't imagine, says University of Arizona Regents'  Professor of planetary sciences H. Jay Melosh.

That mechanism is meteorites.

"The mechanism by which large impacts on Mars can launch boulder-sized surface rocks into space is now clear," said Melosh, who is considered one of the world's foremost experts on impact cratering and the importance of extraterrestrial impacts in shaping life on Earth.

"Both theory and direct measurements on some of these rocks tell us that living microbes could have survived both the launch and travel in the vacuum of space for periods long enough for them to have arrived intact on the surface of our planet," he said.

The reverse journey of surface rocks launched from Earth and landing on Mars is likewise possible, he added.

"Research at the UA and elsewhere has filled in many details of this process. Biological exchange between the planets of our solar system seem not only possible, but inevitable," Melosh said.

Although scientists yet lack proof that such an exchange has actually occurred, "we now know what to look for," he said.

Further discoveries could vindicate Percival Lowell's belief that there was life on Mars before there was life on Earth.

"Life could have originated on the planet Mars and then traveled to Earth," Melosh concludes.

He said, "In that case, we are, in fact, all Martians."

The University of Arizona
Credit: The Planetary Society
Artist's conception of an fragment as it blasts off from Mars. Boulder-sized planetary fragments could be a mechanism that carried life between Mars and Earth, UA planetary scientist Jay Melosh says.
(Credit: The Planetary Society)


Sixth International Mars Society Conference
by The Mars Society

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