Cape Canveral, Florida: Scientists are reporting that Mars appears to have not only frozen water but flowing streams of salty water, at least in the summertime.
They say their latest observations "strongly support" the longtime theory that salt water flows down certain Martian slopes each summer.
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.
Because water is essential to life, Monday's findings could have major implications.
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 Mars Reconnaissance Orbiter, which has been circling Mars since 2006.
Portions of the Martian surface shot by NASA's Mars Reconnaissance Orbiter show many channels from 1 meter to 10 meters wide on a scarp in the Hellas impact basin, in this photograph taken January 14, 2011 and released by NASA March 9, 2011. Scientists have found the first evidence that briny water may flow on the surface of Mars during the planet's summer months, a paper published on Monday showed. Researchers found telltale fingerprints of salts that form only in the presence of water in narrow channels cut into cliff walls throughout the planet's equatorial region. (Reuters/NASA/JPL-Caltech/Univ. of Arizona/Handout)
Brine 'flowing'
Curious lines running down slopes on the Martian surface may be streaks of super-salty brine, said the latest findings Monday in the scientific quest for extra-terrestrial liquid water, a prerequisite for life.
A team from the United States and France said it found evidence in the lines of "hydrated" salt minerals, which require water for their creation.
These results "strongly support the hypothesis" of liquid water on Mars today, concluded a research paper published in the journal Nature Geoscience.
Astrophysicists have long hypothesised that the seasonal streaks, dubbed "recurring slope lineae" (RSL), may be formed by brine flows on the Red Planet.
The lines, up to a few hundred metres in length and typically under five metres (16 feet) wide, appear on slopes during warm seasons, lengthen, then fade as they cool.
But spacecraft images have not been detailed enough to probe what is within the lines - the pixel resolution is coarser than the width of the streaks.
The planet Mars is seen in an image from NASA's Hubble Space Telescope taken August 27, 2003. Scientists have found the first evidence that briny water may flow on the surface of Mars during the planet's summer months, a paper published on Monday showed. REUTERS/NASA/Handout via Reuters
In April, scientists reported in the same journal that perchlorate salts, like the ones in the new study, were "widespread" on the surface of our planetary neighbour and humidity and temperature conditions just right for salty brines to exist.
Perchlorate is highly absorbent and lowers the freezing point of water so that it remains liquid at colder temperatures.
The new study found signs of these same salts in the enigmatic streaks.
"What our paper does is further substantiate that theoretical possibility" of liquid brines on Mars, co-author Lujendra Ojha of the Georgia Institute of Technology in Atlanta told AFP by email.
'Almost' proof
The team devised a method to extract more data from individual pixels in images from the CRISM spectrometer instrument on NASA's Mars Reconnaissance Orbiter, and found details "consistent with the presence of hydrated salt minerals that precipitate (crystallise) from water," according to a Nature press release.
"The findings strongly suggest a link between the transient streaks on Martian slopes and the flow of liquid brines," it added.
Asked if the data was unequivocal proof of liquid water on Mars, another of the study authors, Alfred McEwen from the University of Arizona, told AFP: "I would say almost".
But if there was, it was likely "wet soil, not free water sitting on the surface," he said by email.
It is widely accepted that the Red Planet once hosted plentiful water in liquid form, and still has water today, albeit frozen in ice underground.
Earlier this year, NASA said almost half of Mars' northern hemisphere had once been an ocean, reaching depths greater than 1.6 kilometres (one mile).
But 87 per cent of the precious substance was lost to space.
