COULD THERE HAVE been life on Mars in the past?It was the most important question given to the men and women behind the current Nasa mission on the planet and they now believe they have the answer.“Yes,” says Michael Meyer, lead scientist for the exploration programme from the agency’s HQ in Washington.An analysis of a rock sample collected by Nasa’s Curiosity rover shows ancient Mars could have supported living microbes.Scientists identified sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon – some of the key chemical ingredients for life – in the powder Curiosity drilled out of a sedimentary rock near an ancient stream bed in Gale Crater on the Red Planet last month.This set of images compares rocks seen by NASA’s Opportunity rover and Curiosity rover at two different parts of Mars. On the left is ” Wopmay” rock, in Endurance Crater, Meridiani Planum, as studied by the Opportunity rover. On the right are the rocks of the “Sheepbed” unit in Yellowknife Bay, in Gale Crater, as seen by Curiosity. (Image credit: NASA/JPL-Caltech/Cornell/MSSS)The collected data indicates the Yellowknife Bay area was the end of an ancient river system or an intermittently wet lake bed. The rock is made up of a fine-grained mudstone containing clay minerals, sulfate minerals and other chemicals. This ancient wet environment, unlike some others on Mars, was not harshly oxidizing, acidic or extremely salty.“We have found a habitable environment that is so benign and supportive of life that probably if this water was around and you had been on the planet, you would have been able to drink it,” said chief scientist John Grotzinger of the California Institute of Technology.“We have characterized a very ancient, but strangely new ‘gray Mars’ where conditions once were favourable for life.”Curiosity, carrying 10 science instruments, landed seven months ago to begin its two-year prime mission.-Additional reporting by APMore: Are humans or robots the future of space travel?