The scientists behind the experiment remain divided over how conclusive the evidence for life on Mars is.

Christopher McKay of Nasa’s Ames Research Centre said, in an interview with Discovery News, ‘Finding organics is not evidence of life or evidence of past life. It’s just evidence for organics.’

‘The ultimate proof is to take a video of a Martian bacteria. They should send a microscope — watch the bacteria move,’ said Josheph Miller of USC’s Keck School of Medicine.

‘On the basis of what we’ve done so far, I’d say I’m 99 percent sure there’s life there.’