28th September 2015

NASA reports flowing water on Mars

NASA has announced evidence, for the first time, supporting the presence of liquid water flowing on Mars today.

New findings from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft have provided the strongest evidence yet that liquid water flows intermittently on present-day Mars.

Using an imaging spectrometer on the 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 rise above –23°C (–9°F), and disappear at colder times.

"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 a significant development as it appears to confirm that water – albeit briny – is flowing today on the surface of Mars."

These downhill flows, known as recurring slope lineae (RSL), have often been described as possibly related to liquid water. The new findings of hydrated salts on the slopes point to what that relationship may be to these dark features. The hydrated salts would lower the freezing point of a liquid brine – just as salt on roads here on Earth causes ice and snow to melt more rapidly. Scientists say it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.

"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. In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks," said Lujendra Ojha, a PhD candidate in Planetary Science at Georgia Institute of Technology, and lead author of a report on these findings published today in Nature Geoscience.

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Liquid water at the surface and subsurface increases the possibility that life could be present: "We know from the study of extremophiles on Earth that life can not only survive, but thrive in conditions that are hyper-arid, very saline or otherwise 'extreme' in comparison to what is habitable to a human," said Dr Joe Michalski, a Mars researcher at the Natural History Museum in London. "On Earth, wherever we find water, we find life. That is why the discovery of water on Mars over the last 20 years is so exciting."

Furthermore, there are implications for human colonists in the future, who may find it easier to form self-sustaining habitats: "It may decrease the cost – and increase the resilience – of human activity on the planet," said co-author Mary-Beth Willhelm, from NASA's Ames Research Center in California. "Looking forward, it is imperative for us to further understand the source of the water for these features, as well as the amount."

The dark streaks pictured here are 0.5 to 5 metres wide and up to 300 metres long. They combine to form extensive fan-like patterns. The discovery of these water flows was made when scientists developed a new technique to analyse chemical maps of the surface. However, only 3% of Mars has so far been covered at resolutions high enough to see these features. The researchers plan to look for more locations where flows may occur. In addition to satellite data, NASA's rovers have been finding a lot more humidity in the air and moisture in the soils than previously thought.

"We're revolutionising our understanding of this planet," said Jim Green, the agency's director of planetary science. "Mars is not the dry, arid planet that we thought of in the past."

"It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future," said lead scientist for NASA’s Mars Exploration Program, Michael Meyer.

NASA plans to send humans to Mars in the 2030s and is developing a huge new rocket – the Space Launch System (SLS) – to make this possible.

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