The discovery has far-reaching implications for the chances of finding life on Mars and future human exploration.
Flowing liquid water, essential to life, is almost certainly present on Mars, scientists believe.
Experts think water is responsible for mysterious darkish streaks on the Red Planet that appeared to ebb and flow with the seasons.
A new high resolution technique has revealed gully-like features at four locations, known as recurring slope lineae (RSL), contain salt minerals which are consistent with briny water.
The salts, which are not found in the surrounding terrain, are thought to have been left by water flowing down the sides of hills or crater rims.
If the discovery is confirmed it has far-reaching implications for the chances of finding life on Mars and future human exploration.
Writing in the journal Nature Geoscience, the scientists concluded: “Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars.
“Water is essential to life as we know it. The presence of liquid water on Mars today has astrobiological, geologic and hydrologic implications and may affect future human exploration.”
The research is based on an analysis of images taken from the American space agency NASA’s Mars Reconnaissance Orbiter spacecraft.
Studying the different wavelengths of reflected light gives a chemical “fingerprint” of what a substance is made up of.
The Mars scientists developed an enhanced technique that allowed chemical signatures to be taken from individual image pixels, providing a much higher level of resolution than could previously be achieved.
John Grunsfeld, an astronaut and associate administrator of NASA’s science mission directorate, said: “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.
“This is a significant development, as it appears to confirm that water – albeit briny – is flowing today on the surface of Mars.”
PhD student Lujendra Ojha, from the Georgia Institute of Technology in Atlanta, who was the lead author of the report, said the findings were further proof that the lines on the Martian slopes were caused by present-day water.
He said: “When most people talk about water on Mars, they’re usually talking about ancient water or frozen water.
“Now we know there’s more to the story. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for RSL.”
Michael Meyer, lead scientist for NASA’s Mars exploration programme, said: “It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet.”
However, it is still not known where the water comes from although there are a number of theories.
These include the melting of near-surface ice, absorption from the thin Martian atmosphere, and seasonal discharges from water-bearing rock.
Source: Sky News