However, Dr Gilbert V. Levin, from the University of Arizona, and Dr Patricia Ann Straat, from the National Institute of Health, now claim this was in fact proof of life on Mars.
The duo wrote in a study published in Astrobiology: “Each of these characteristics is reminiscent of responses by a compendium of terrestrial microorganism species, including the initial positive responses, the 160C and 50C heat controls, the reabsorption of evolved gas upon second injection of nutrient, and death from isolated long-term storage.”
They added the results were “consistent with a biological explanation”.
With manned missions to Mars now very much on the horizon, the pair say the results need to be confirmed for health and safety reasons for when humans do make it to Earth’s neighbour.
Dr Levin and Dr Straat continue: “Plans for any Mars sample return mission should also take into account that such a sample may contain viable, even if dormant, alien life.”