Evidence that water may flow on Mars in summer

CAPE CANAVERAL: 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 yesterday showed.

Although the source and the chemistry of the water is unknown, the discovery could affect thinking about whether the planet that is most like Earth in the solar system could support present-day microbial life.

Scientists developed a new technique to analyse chemical maps of the Martian surface, obtained by Nasa’s Mars Reconnaissance Orbiter spacecraft.

They 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. The slopes, first reported in 2011, appear during the warm summer months on Mars, then vanish when the temperatures drop. Scientists suspect that the streaks, known as recurring slope lineae, or RSL, were cut by flowing water, but had previously been unable to make the measurements.

“I thought there was no hope,” Lujendra Ojha, a graduate student at Georgia Institute of Technology. Mars Reconnaissance Orbiter makes its measurements during the hottest part of the Martian day, so scientists believed any traces of water, or fingerprints from hydrated minerals, would have evaporated.

Also, the chemical-sensing instrument on the orbiting spacecraft cannot home in on details as small as the narrow streaks. But Ojha and colleagues created a computer program that could scrutinise individual pixels. That data was then correlated with high-resolution images of the streaks. Scientists came up with a 100 percent match between their locations and detections of hydrated salts.

“We’re not claiming that we found... evidence of liquid water. We found hydrated salts,” Ojha said. Still, that was enough for Nasa, which declared a “Mars mystery solved”.

Whatever the water’s source, the prospect of liquid water, even seasonally, raises the intriguing prospect that Mars, which is presumed to be a cold and dead planet, could support life today.