For lifeless chemical compounds to organize themselves into something alive, scientists generally agree, three sets of things must be present:
? Standing water and an energy source.
? Five basic elements: carbon, oxygen, hydrogen, phosphorus and nitrogen.
? And time, lots of time.
In its search for environments where life might have started on Mars, the Curiosity rover has found the standing water, the energy and the key elements with the right atomic charges. As a result, scientists have concluded that at least some of the planet must have been habitable long ago.
via New York Times
