Calif. Carol Stoker, a robotics expert at Ames, agreed. But robots are simply the tools for gathering data for humans. For geological fieldwork, nothing will work better than the human in the field. Whether people or machines do the work, researchers say that the exploration of Mars has greater value than simply satisfying curiosity about an alien world. It can also help solve Earthly riddles.
Scientists always demand more than one experiment to prove a hypothesis.
So far, however, Earth is the only laboratory available to study how living creatures evolved from a single, primordial ancestor. On Earth, all life is a variation on a single theme. It is possible, for example, that extraterrestrial life could arise without the particular combination of carbon-based chemicals, mild temperatures and plentiful energy available on our own planet. Some scientists, such as Norman Sleep, a geophysicist at Stanford University in Palo Alto, Calif., even contend it is more likely that life arose first on Mars and was transported to Earth aboard a meteorite. That is because Mars suffered less than Earth from bombardment by giant space rocks, which could have allowed primitive microorganisms to develop beneath the surface.