Ancient traces of water found on Mars

For a vehicle designed to last just 7 earth weeks, Opportunity has done remarkably well. Ten years to the day since the rover first landed on the surface of Mars, its new analysis of some of the oldest rocks ever found there show environments potentially suitable for life were around on the planet much earlier than we previously thought.

The samples, estimated at over 4 billion years old, contained clay minerals, rich in iron and aluminium, that suggest the red planet may have been much warmer and wetter in the very distant past.

According to the mission’s Deputy Principal Investigator Ray Arvidson: “these rocks are older than any we examined earlier in the mission, and they reveal more favourable conditions for microbial life than any evidence previously examined by Opportunity.”

Since it landed in a crater on the Meridiani plains on January 25 2004, Opportunity has sent 170,000 images back to earth, alongside data from its two spectrometers, which can analyse the chemical composition of soil and air samples. Its many significant discoveries include the first meteorite ever seen on another planet, and soil layers similar to structures on Earth that appear to have been caused by the movement of wind and water in the distant past. It has also performed a detailed analysis of the Martian atmosphere through tracing of argon gas.

Opportunity has travelled 25 miles from its original landing site to the Endeavour crater, where its most recent results have come from. Its path has been guided by data from the Mars Reconnaissance Orbiter, a NASA satellite that can take highly detailed photographs of the planet’s surface.

Opportunity is one of a number of craft currently analysing the environment on Mars. Its larger cousin Curiosity, which landed in Gale crater in July 2012, has already made significant discoveries. In December last year, it encountered evidence of a huge lake that existed around 3.5 billion years ago. Much like Opportunity’s recent discovery, the water had a neutral pH, and contained key elements vital for life on Earth, such as carbon, nitrogen and phosphorus, potentially making it an ideal place for microbes to live. The discovery prompted John Grotzinger, project scientist for Curiosity, to describe parts of Mars as “extremely Earthlike”.

So far though, while many potentially habitable environments have been found on the planet, no complex organic molecules – the building blocks of life on earth – have yet been detected. Such a discovery could provide the first direct suggestion that some forms of life may have existed there in the past: one of the key aims of Mars exploration.

Nobody knows how much longer Opportunity has left until its systems begin to stop working. Its twin, Spirit, which landed around the same time, stopped sending back information four years ago. Intense dust storms and huge temperature fluctuations make Mars an inhospitable location for any piece of technology. Many electrical components have stopped working, and one of its wheels is broken. But despite this, Opportunity’s condition has deteriorated relatively little recently, and it is fully expected to keep going for another few years yet.

“There’s more good stuff ahead,” said Steve Squyres, Opportunity’s principal investigator. “We’re examining a rock right in front of the rover that’s unlike anything we’ve seen before. Mars keeps surprising us, just like the very first week of the mission.”