The presence of liquid water is thought to be a necessary condition for life on a planet.
Consequently, the search for life outside of Earth has embraced the mantra, “follow the water”. But, as noted in a recent summary posted here, much of the evidence for water on Mars can better be explained in other ways.
In a new evaluation of data collected from the two Mars Exploration Rovers (MER), Spirit and Opportunity, Andrew Knoll, a member of the rover science team and a biologist at Harvard University, reported that evidence preserved in the rocks on the surface of Mars suggests that any water that may have existed in the Red Planet’s history was very salty.
Knoll presented his report in Boston at the 2008 annual meeting of the American Association of the Advancement of Science. In his talk, Knoll explained that water on Mars was “salty enough that only a handful of terrestrial organisms would have a ghost of chance of surviving there when conditions were at their best.” He also noted that previous mission data have indicated that liquid water in the same areas would also have been very acidic. “So it is doubly bad if it’s acidic and salty,” Knoll said.
While this was bad news for those searching for evidence of Martian life, many Mars scientists still maintain hope. The two rovers will continue their investigation. Also, upon further research, other areas on Mars may prove more hospitable to life. In May 2008, Mars spacecraft Phoenix Lander will arrive near Mars’ north pole and dig down into the surface for evidence of water and possible life. In 2009, NASA will send the Mars Science Laboratory (MSL), a far more sophisticated rover twice the size and five times the weight of the MERs. All of these machines are meant to provide much more detailed information on both the presence and history of water in the Mars environment, and will include experiments that can detect organic material.
Reasons To Believe scholars have discussed the question of life on Mars and the likelihood that any evidence of life discovered there would have originated on Earth (see here and here). From this new report we can draw the further conclusion that it is not sufficient to just find water. The water must not be contaminated. It serves as a reminder that “following the water” does not necessarily lead to life.