Wednesday | February 25, 2009
Are we all Martians? The Meteoritic Exchange of Life between Planets
~ Professor Leon and Pauline Blitzer Award for Excellence ~
In the Teaching of Physics and Related Sciences
AWARDEE AND SPEAKER
H. J. Melosh, Ph.D.
Regents Professor of Planetary Science, Lunar and Planetary Science Lab
Email: jmelosh@lpl.arizona.edu
The first hint that our Earth and Mars are not biologically isolated arose in 1980 when research on a class of unusual meteorites suggested that they might have originated on another large planet, perhaps Mars. Since then, the Martian connection has been proven beyond all reasonable doubt. The mechanism by which large impacts on Mars can launch boulder-sized surface rocks into space is now clear. 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 reached the vicinity of Earth, decelerated in our atmosphere and arrived intact on the surface of our planet. Even the reverse journey, Earth to Mars is plausible. Research both at the University of Arizona and elsewhere has filled in many details of this process and made biological exchange between the planets of our solar system seem not only possible, but inevitable. Although there is not yet any proof that such exchange has actually occurred, we now know what to look for. It seems possible that Percival Lowell was right, in a way not imagined by him, and that life could have originated on the planet Mars and then traveled to Earth. In that case, we are, in fact, all Martians.
