Discovery bodes well for possibility of life on Mars
Scientists at NASA reveal evidence of flowing water on red planet
In a find sure to jolt the search for life on Mars, NASA scientists announced Monday that evidence of flowing water has been discovered on the red planet.
Signs of briny flows seeping from Martian peaks and craters were detected by instruments aboard the Mars Reconnaissance Orbiter, which has been surveying the planet since 2006. Water is essential for life as we know it, so its presence — especially near the surface — suggests “it would be possible for there to be life today on Mars,” said John Grunsfeld, head of NASA’s Science Mission Directorate.
The space agency’s scientists leveraged the findings to make the case for human exploration of the red planet.
“Today’s announcement of a really fas- cinating result about current water on Mars is one of the reasons why I feel it’s even more imperative that we send astrobiologists and planetary scientists,” added Grunsfeld, a former astronaut.
Scientists know that arid Mars once bore water because its surface is covered by dry deltas and ocean beds.
Martian life may have existed then, but to investigate whether it still does — likely in microbial form — researchers wanted to discover whether liquid water still exists anywhere on the planet’s surface.
The first hint it could came from an instrument aboard the Mars Reconnaissance Orbiter, called HiRISE, which snaps super-high-resolution pictures of Mars’s surface. After several years of observations, the scientists using HiRISE noticed a strange phenomenon: dark streaks that appeared on steep Martian mountain ridges in the spring, grew in summer, then faded by fall. The streaks, a few metres wide and hundreds of metres long, were named “recurring slope lineae.”
To probe the properties of the streaks, researchers used a different instrument known as a spectrometer, which analyzes light. Because different chemicals absorb wave- lengths of light at different rates, the research team could compare light reflected from the lineae to light reflected from different chemicals in labs on Earth, and search for the closest fit.
What the spectrometer found in those wavelengths were the telltale signatures of hydrated salts: briny water. When the streaks were gone, the signatures were gone. The scientists’ conclusion: an active water system was washing the salts onto the high slopes of Mars in warm months, and dissipating in the cold.
“Mars is not the dry, arid planet that we thought of in the past,” said Jim Green, NASA’s director of planetary science. “Under certain circumstances, liquid water has been found on Mars.” The results were also published in Nature Geoscience.
The brines are so salty that they would burn human flesh, experts said. But there is a precedent for life in such extreme environments: scientists have discovered microbes living in rock salt below the surface of Chile’s ultra-arid Atacama Desert. The salty substrates attract moisture from the air, a process known as deliquescence — the same process researchers believe may be at play on Mars.
Paul Delaney, a professor of physics and astronomy at York University, noted that the space-science community would continue to debate interpretations for the Orbiter’s evidence, but “I see no reason to disbelieve the data,” he said. “If you don’t find signs of liquid water flowing, it makes the case for life harder. This makes the case easier, but it doesn’t say ‘Yeah, we’ve got life.’ ”
Delaney agreed that the discovery buttresses the rationale for sending humans to Mars. The location of the water streaks, high on steep ridges, makes followup investigation difficult for a robotic rover.
“It’s really easy for you or I to act as a mountain goat,” he said. “We are a much more dexterous terrain vehicle.”
Crucially, the brininess of the water also makes supporting human life more feasible. Salts lower the freezing point of water, making it more stable in liquid form.
“The possibility of long-term survival on the surface of Mars goes up dramatically when you know there are serious and significant deposits of water or ice just below your feet,” said Delaney.
Significant scientific hurdles remain before any long-distance human space travel can be attempted. But Delaney and others believe the limiting factor is political will: a flight program would cost billions of dollars. On Monday, NASA scientists seemed to see the discovery as an opportunity to make their case.