Mars appears to be flowing with streams of salty water, at least in the summer, scientists have reported. Such a finding boosts the chances of life on the red planet.
“It suggests that it would be possible for there to be life today on Mars,” said Nasa’s science mission chief, John Grunsfeld.
Scientists in 2008 confirmed there was frozen water on Mars. Now instruments on Nasa’s Mars Reconnaissance Orbiter have found the strongest evidence yet that salt water in liquid form trickles down hillsides each summer, according to the researchers.
“Mars is not the dry, arid planet that we thought of in the past,” said Jim Green, director of planetary science for Nasa. “Under certain circumstances, liquid water has been found on Mars.”
The streams – if that’s what they are – are about three to four metres wide and 90 metres or more long.
“What we’re dealing with is wet soil, thin layers of wet soil, not standing water,” said Alfred McEwen of the University of Arizona, in the US, at Tucson, the scientist in charge of images taken by the Orbiter.
A stream of consciousness?
The findings suggest there could be life – something that can only exist with liquid water. The researchers said further exploration will look for microscopic life.
McEwen said he believes the possibility of life on Mars to be “very high”, though it would be microbial.
The presence of liquid water could also make life easier for astronauts on Mars. Water could be used for drinking, creating oxygen, and rocket fuel. Nasan wants to send humans there in the 2030s.
The evidence of flowing water consists largely of dark, narrow streaks on the surface that tend to appear and grow during the warmest months and fade the rest of the year.
"The idea of water — and life — on Mars has been irresistible to earthlings for generations."
Mars is extremely cold even in summer, and the streaks are in places where the temperature is as low as -23 degrees Celsius. However, salt can lower the freezing point of water and melt ice.
The source of the water is a mystery. Scientists think it could be melting ice, underground rock, water vapour from the thin Martian atmosphere, or a combination.
McEwen said that there appears to be a “significant volume” of water that could fill many Olympic swimming pool, though it is currently spread too thin for any swimming.
The streaks were spotted by the orbiter’s high-resolution, telescopic camera, and another instrument worked out there was salt combined with the water.
Michael Meyer, lead scientist for Nasa’s Mars exploration programme, said the only way to determine whether there’s life on Mars is to collect rocks and soil for analysis on Earth – something a US lander set for liftoff in 2020 will do.
Telescopes to microscopes
Now that scientists know what they’re looking for, a careful search can be carried out, Green said.
“Water is one of the resources necessary for a human mission to the red planet,” said Lamar Smith, chairman of the science, space and technology committee of the US House of Representatives. “The more evidence we find of it, the more encouraged I am for future Mars missions.”
Present-day Mars is nothing like ancient Mars. Three billion years ago, our most Earth-like neighbour had a huge ocean, but something radical happened, and exactly what remains a mystery.
In 2008, Nasa’s Phoenix spacecraft landed on Mars and found ice in the soil. The Mars Reconnaissance Orbiter has been circling the planet since 2006.
And the timing couldn’t be better. This week, the Nasa-approved movie The Martian opens in cinemas worldwide.