A former Nasa scientist has reignited the debate over extraterrestrial life by claiming that evidence of alien organisms was found on Mars during the 1970s. In an op-ed for Scientific American, Gilbert Levin, who worked on the agency's Viking missions, argues that the presence of life on the Red Planet was effectively confirmed more than four decades ago.
Levin, who spearheaded the Labeled Release life detection experiment, points to the results from Nasa's Viking Landers 1 and 2, which touched down on Mars in 1976. The landers collected soil samples and mixed them with organic compounds, looking for signs of carbon dioxide that would indicate metabolising microorganisms. According to Levin, the tests produced four positive results, with both landers reporting the same outcome from sites located roughly 4,000 miles apart.
Despite these initial findings, Nasa concluded that the mission provided 'no clear evidence for the presence of living microorganisms in soil near the landing sites'. However, Levin contends that subsequent discoveries, including evidence of water and organic compounds on Mars, along with the failure of 43 later studies to offer a definitive nonbiological explanation, have strengthened his case.
Levin also criticises the lack of follow-up investigations, noting that Nasa's upcoming 2020 Mars lander will not carry a life-detection test. He has called for future missions to include more advanced equipment capable of identifying microorganisms, arguing that a fresh examination of the Viking data could provide important guidance for Nasa's search for life.
