New findings from NASA's Mars Reconnaissance Orbiter provide the strongest evidence yet that liquid water flows intermittently on present-day Mars, the agency announced Monday.

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet.

These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees (minus 23 Celsius), and disappear at colder times.

These dark, narrow streaks tend to appear and grow during the warmest Martian months, and fade the rest of the year. Salt lowers the freezing point of water, and scientists say that would explain these seasonal briny flows.

"Our quest on Mars has been to 'follow the water,' in our search for life in the universe, and now we have convincing science that validates what we've long suspected," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "This is significant development as it appears to confirm that water — albeit briny — is flowing today on the surface of Mars."

The researchers say further exploration is warranted to determine whether any microscopic life might exist at modern-day Mars. They based their findings on data from NASA's MRO, which has been circling Mars since 2006.

"We found the hydrated salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration," said Lujendra Ojha, of the Georgia Institute of Technology (Georgia Tech) in Atlanta, lead author of a report on these findings published Sept. 28 by Nature Geoscience. "In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks."

Dark narrow streaks called recurring slope lineae emanating out of the walls of Garni crater on Mars. The dark streaks here are up to few hundred meters in length. They are hypothesized to be formed by flow of briny liquid water on Mars. (NASA/JPL/University of Arizona)