NASA announced last night that liquid water is still flowing on Mars. The “major science finding” promised by the space agency turned out to be confirmation that salty water is thought to have been detected running down slopes on the Red Planet.
It also means that there could be a plentiful supply of water for future astronauts to process and turn into drinking water—though future mission organisers will have to be even more vigilant that they do not contaminate Mars with bugs carried from Earth.
The presence of the flowing water, or brine, was revealed by strange streaks that appear and then fade away with the changing seasons on Mars. Around three miles wide, they appear on the slopes during the warmer martian days, then fade away during the cooler seasons.
The water-produced streaks—known as recurring slope lineae—were first spotted in 2011 by planetary scientist Lujendra Ojha, who has led research into what caused them. He always believed they were being produced by salty liquid water. He said yesterday: “Key evidence was missing until now.”
He added: “When most people talk about water on Mars, they’re usually talking about ancient water or frozen water. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for recurring slope lineae.”
Hundreds of the streaks have been seen from orbit flowing down some hills. Now the scientists have analysed data recorded by an instrument called CRISM aboard NASA’s Mars Reconnaissance Orbiter, which watches the planet in different colours of light, and check how the light is absorbed by different minerals.
CRISM was able to pick out from individual pixels in the photos just what the material on the ground was made of. It confirmed that the streaks were all consistent with the presence of hydrated salt minerals which are produced from liquid water.
The spectral “fingerprints” that revealed the presence of the salts is not found anywhere else on the terrain surrounding the streaks. This evidence convinced the NASA scientists that the streaks are formed by flowing salty water.
Similar water deposits, known as perchlorates, have previously been discovered from the surface of Mars by NASA’s Phoenix lander in 2008, and Curiosity rover, which is currently roaming around an ancient lake bed in Gale Crater.
Michael Meyer, lead scientist for NASA’s Mars Exploration Program, said yesterday: “These are dark streaks that for in the spring, grow through the summer and then disappear in the fall.”
He added: “It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet.
“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.”
Mars lacks a protective magnetic shield and so is bombarded with ultraviolet light from the sun that would prove fatal to unprotected life on the surface of Mars. But many scientists believe living bugs might live on underground.
NASA associate administrator and astronaut John Grunsfeld said yesterday: “We are going to Mars. soon I hope we’ll be sending humans to the red planet to explore, and science leads the way.
“Is there current life on Mars? The more we observe Mars, the more information we’re getting that Mars is a fascinating planet and was once like Earth. But Mars lost its water.
“Did life exist on Mars and did any survive? Is there life on Mars today? We can answer that by sending probes.”