If NASA's Mars rover, Curiosity, safely touches down on Sunday night, it will begin searching for organic molecules in the Red Planet's soil. What would happen if the rover found something?
In this weekly series, Life's Little Mysteries provides expert answers to challenging questions.
If all goes as planned, NASA's Curiosity rover will touch down on Mars late Sunday night. Then, after a few weeks' respite, it will begin probing the subsurface soils looking for organic molecules that could be the detritus of ancient Martian life.
A few billion years ago, vast oceans might have sloshed over the surface of the Red Planet, and a thick atmosphere probably enshrouded it. The liquids and gases have all but burned away by now, but any organisms Mars harbored in its ancient glory days would have left behind traces in the form of large, carbon-based molecules. "Organic molecules can last for billions of years," explained Alexander Pavlov, a planetary scientist at NASA's Goddard Space Flight Center.
Any simple organic matter Curiosity digs up could have biological origins, but it could also have been generated through more mundane chemical processes. However, if the rover detects complex organic structures — the kind we find in living things, and practically nowhere else but Earth — these would be "a very strong indicator" of ancient life on Mars, Pavlov told Life's Little Mysteries.
As Seth Shostak, senior scientist at the SETI Institute, put it, "It would be like finding 2-ton blocks of limestone in the desert in Egypt and saying, hmm, these might be leftover pieces of a structure around here somewhere."
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