Scientists have found new evidence for possible saltwater flows on Mars. The discovery was announced at a NASA news conference Thursday.
Alfred McEwen, lead author of the Science journal study showing these observations, and his team have been observing Mars using the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter. His team has identified features on some slopes of the planet that appear to fade in the winter and come back in the spring.
These flows occur near the Mars equator in its southern hemisphere, where temperatures would be suitable for liquid water. Since Mars is about 50 million miles farther from the sun than Earth, temperatures rarely break the freezing mark. At the equator, summer highs can reach 70 degrees Fahrenheit (about 20 Celsius). But in the middle latitudes, where the observations disclosed Thursday were taken, temperatures range from about 32 degrees F at summer noon to overnight lows of -75 F (-60 C).
The water is expected to be briny because previous study of the planet has shown that its surface is salty, so any water that flows in the subsurface is going to be salty.
Seven such sites on the planet have been confirmed, with 20 more possible, McEwen said.
“What makes these new observations so interesting is they occur at much lower latitudes where temperatures are much warmer and where it’s actually possible for liquid water to exist,” said Arizona State University geophysicist Phil Christensen, one of the scientists who studied the images beamed back from the orbiter.
The study does not prove water exists, but identifies it as the best explanation. It's worthwhile to think about alternative reasons for these observations, but none seems to fit as well as briny water, McEwen said.
"I think it’s going to be laboratory experiments on Earth that give us the best confirmation or refutation," he said.
The water may be higher in density and viscosity than what we're used to on Earth, to the point that it may appear syrup-like.
So what does this mean for life on Mars? If Mars has water that flows as a liquid in warmer times and freezes at others, if organisms live there, they might go into a resting state during winter, said Lisa Pratt, professor of geological sciences at Indiana University, Bloomington. This is pure speculation, however.
"It is our first chance to see an environment on Mars that might allow for the expression of an active biological process, if there is presently life on Mars," Pratt said.
