Life on Mars: Water on the Red Planet Changes the Conversation About Its Potential Habitability

Mars water
NASA scientists believe that the 100-meter long dark streaks on the surface are Mars are caused by contemporary flowing water. NASA/JPL/University of Arizona

NASA's announcement that liquid water may run on the surface of Mars brings the possibility of life on the planet closer than ever before, according to experts.

Scientists found evidence that, during summer months on Mars, liquid water runs down canyons and crater wall. The researchers are not sure where the water comes from but speculate that it may rise up from underground ice or salty aquifers—underground layers of permeable rock or unsettled materials.

Andrew Coates, head of planetary sciences at University College London, says that the discovery will transform the way in which the question of whether there is life on Mars is approached. Previously, evidence from NASA's Curiosity Rover suggested that Mars may have been able to support microbial life around 3.8 billion years ago, when the planet's environment was warmer and wetter. "Evidence like this helps towards saying that conditions not only were right but perhaps may even be right now for life on Mars," says Coates.

Coates is also the principal investigator on the ExoMars PanCam project—a panoramic camera that will be attached to a rover the European Space Agency (ESA) is scheduled to send to Mars in 2018. Coates says that the new discovery makes the ESA's ExoMars Program even more pertinent. The mission will be the first to drill up to two meters beneath the planet's surface, which could potentially reveal the source of the water detected by NASA.

"If we can see liquid water now, it increases the possibility [of success] for missions like ours looking for potential life on Mars," says Coates. "Maybe this is the tip of an iceberg for what's underneath."

Doug Millard, Deputy Keeper of Technologies and Engineering at the U.K.'s Science Museum in London, concurs. "Evidence of running water on the surface of Mars, perhaps recently, is tremendously exciting," says Millard, who adds that the discovery makes it even more likely that past or even existing forms of life could be discovered on Martian soil.

NASA scientists identified streaks in certain areas of the Martian surface, which darkened during warm seasons when temperatures reach above minus 10 degrees Fahrenheit (minus 23 degrees Celsius), and disappeared at cooler times. The team detected signatures of hydrated salts present on the surface, indicating that the streaks were created by salty water flowing down the planet's surface. However, they were unable to determine where the water is coming from. As well as rising up from underground ice or reservoirs, moisture from the air could be absorbed by the salts. However, this latter option appears unlikely due to the extremely low humidity in Mars' atmosphereonly enough for 10 microns of rain across the entire planet, equivalent to 1/2,500th of an inch, The New York Times reported.

Joe Michalski, a Mars researcher at the U.K.'s Natural History Museum, said that the salinity of the waterdescribed as "briny" by the NASA researchersdid not rule out the chances that it could give rise to life. "We know from the study of extremophiles"—microbes which live in conditions of extreme temperature, acidity, alkalinity or chemical concentration"—on Earth that life can not only survive but thrive in conditions that are hyperarid, very saline or otherwise extreme in comparison to what is habitable to a human," says Michalski.

Previous discoveries of permafrost and ice on Mars gave rise to the suggestion that liquid water may once have flowed on the Red Planet. But this recent finding, says Michalski, is "a hugely important one because it points to environments that could potentially be habitable to certain kinds of bacteria, even today."

Of course, adds Coates, the presence of liquid water does not mean that life on Mars is a sure thing. "Water is one of the things you need for life but you also need the right chemistry," he says. You need a source of heat to drive chemical reactions which would lead to life and you need enough time for life to develop."