NASA has denied the claims of former astronaut Gilbert Levin who said that the agency has already discovered signs of alien life on Mars during the 1970s. 

In a report, NASA refuted the explosive claims of Levin who said his team was able to detect signs of microbial respiration, which pretty much indicated that there could be life on the dry and dusty planet. Per NASA, the probes did not beam back any conclusive evidence of alien life forms from the Red Planet and that data from the Viking experiments have actually sent back “false readings.” 

In the report which first appeared on Fox News, the U.S. space agency said that most scientists "do not believe the results of the Viking experiments alone rise to the level of extraordinary evidence." 

Dr. Levin has claimed that he and his team are responsible for bringing back the only legitimate evidence and encounter with actual aliens from Mars. NASA’s Viking Mission was the first space mission to ever land on the surface of Planet Mars. According to the report, the twin Viking landers of NASA discovered the signs of microbial respiration, but succeeding experiments could not trace any evidence that shows organic molecules exist on Martian soil. 

Levin worked as the lead investigator of the Labeled Release (LR) experiment. The LR experiment basically included inoculating Martian soil with nutrients and looking for signs of metabolism that could lead to showing signs of microbial life forms. 

However, NASA failed to detect any other physical evidence that life was there. The space agency revisited the findings of the Viking mission back in 2016 after digitizing data stored in microfilms. 

“The science team believed the LR data had been skewed by a non-biological property of Martian soil, resulting in a false positive. While arguments continue, this remains the consensus view," NASA said in a statement. 

The statement has obviously frustrated Dr. Levin. "NASA concluded that the LR had found a substance mimicking life, but not life," he said in an article in the Scientific American called “I’m Convinced We Found Evidence of Life On Mars in the 1970s.” "Inexplicably, over the 43 years since Viking, none of Nasa's subsequent Mars landers has carried a life-detection instrument to follow up on these exciting results."

Mars Dunes This captivating image was taken in the north polar region of Mars by the ESA/Roscosmos ExoMars Trace Gas Orbiter’s CaSSIS camera. Photo: ESA/Roscosmos/CaSSIS