mARS
These dark, narrow, 100metre-long streaks called recurring slope lineae flowing downhill on Mars are thought to have been formed by flowing water Nasa/JPL/University of Arizona

Nasa has announced the discovery of traces of "briny flows" on the surface of Mars in a revelation that could point to life on the Red Planet. The US space agency put out a statement titled Nasa to announce Mars mystery solved on 24 September, stating that it will announce a "major science finding from the agency's ongoing exploration of Mars" at a news briefing on 28 September.

Thoughts had arisen that it would claim to have discovered water on Mars and space enthusiasts will be excited by the news, which comes after years of research. The research team, headed by Lujendra Ojha, analysed high resolution images of mountainous structures on Mars and found surface features called recurring slope lineae which are consistent with being formed by flowing salt water.

Mars
Dark narrow streaks called recurring slope lineae on the walls of Garni crater on Mars. The streaks are up to few hundred metres in length, and thought to be formed by flow of briny liquid water Nasa/JPL/University of Arizona

The recurring slope lineae are narrow – usually less than five metres in width and appear during the warmer months, according to a study published in Nature Geoscience, while they contract in Mars' winter. A statement read: "The range of surface temperatures over which the recurring slope lineae are active suggests that salty liquid water may be involved in their formation."

Ojha and colleagues analysed spectral data from the CRISM instrument on-board Nasa's Mars Reconnaissance Orbiter to look at where recurring slope lineae are on the planet. The team was able to identify spectral information from single pixels and found that "all locations examined are consistent with the presence of hydrated salt minerals that precipitate from water", while there was no evidence of salt in the surrounding terrains, suggesting that the water follows a flowing path.

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The image shows dark narrow streaks called recurring slope lineae flowing down the west facing slopes of Coprates Chasma in the equatorial region of Mars Nasa/JPL/University of Arizona

It has long been theorised that there are briny flows on Mars. Back in 2011, Ojha, admittedly serendipitously, discovered the possibility that salt water may flow on the surface of the Red Planet in the warmer months.

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Recently, planetary scientists detected hydrated salts on these slopes at Horowitz crater, corroborating their original hypothesis that the streaks are indeed formed by liquid water Nasa/JPL/University of Arizona

Ojha was studying Mars when he noticed apparent gullies – which are the result of flowing water – on the planet. By using a computer algorithm to examine images of craters and the seasonal changes, he was able to identify irregular features within a crater that were not the result of gullies, and could have been recent water tracks.

He told CNN in 2011: "When I first saw them, I had no idea what it was. I just thought it was a streak made by dust or something similar. It was a lucky accident. There's going to be years of research put into this to even prove that this is definitely a proof of water. And from that, we can move on: OK if this is water, what are the chances that life could be in these kinds of surroundings?"

You can watch the press conference, which kicks off at 4PM on 28 September, here.

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