Scientists have found new evidence for possible saltwater flows on Mars. The discovery was announced at a NASA news conference Thursday at the space agency's headquarters in Washington.
Alfred McEwen, lead author of the Science journal study showing these observations, and his team observed Mars using the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter. His team identified features on some planet slopes that appear to fade in the winter and come back in the spring.
These flows occur near 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 is from the sun, temperatures rarely break the freezing mark. Before the new findings, water was thought to exist in the form of ice in Mars' polar regions, and has also been detected at mid-latitudes. This is the first time there's good evidence for liquid water existing on the planet.
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 implicated in the new study is expected to be briny because previous study of Mars has shown that its surface is salty. The flows are finger-like and small; nowhere near the size of major rivers on Earth. They are also very narrow: 0.5 to 5 yards, or meters, wide.
Seven sites with these possible liquid flows have been confirmed on the planet, with 20 to 30 more possible, scientists said. In some locations, there are more than 1,000 individual flows.
“What makes these new observations so interesting is they occur at much lower latitudes [closer to the equator], 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 more dense and viscous 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 organisms live on the planet, they might go into a resting state during winter, if Mars does have water that flows as a liquid in warmer times and freezes at others, said Lisa Pratt, professor of geological sciences at Indiana University, Bloomington.
"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.
CNN's Matt Smith contributed to this report.