NASA discovered evidence of life on Venus in 1978, a scientist has claimed.
Biochemist Rakesh Mogul said a probe picked up signs of phosphine during the Pioneer 13 mission to the 463C planet.
British and American astronomers last month announced they had found the chemical - a sign of life - in its atmosphere.
In an interview to Live Science, the academic at Cal Poly Pomona in California said: "When the [Nature Astronomy paper] came out, I immediately thought of the legacy mass spectra."
Dr Mogul said his team made the finding while searching back through NASA's archives.
Data was collected from the Large Probe Neutral Mass Spectrometer that was dropped into the atmosphere of Venus as part of the Pioneer 13 mission.
He said analysis of the original scientific articles looking for phosphorus compounds from that data revealed signs of phospine - which is often a creation of microbial life.
It comes after researchers confirmed they had discovered the gas in Venus's atmosphere last month.
Study author Sara Seager, a planetary scientist at the Massachusetts Institute of Technology, said: "This is an astonishing and ‘out of the blue’ finding.
“It will definitely fuel more research into the possibilities for life in Venus’s atmosphere.”
Astrophysicist at San Francisco State University and University of San Francisco, Aaron White, told IGN: "One of astronomy's biggest unanswered questions is whether life on Earth is rare and unique, or if we're just one of many places all throughout the universe filled with living things.
"This discovery is the most solid evidence we've had so far to suggest life could be common. There are several different places in our solar system where we've guessed life could be discovered, and Venus was definitely the most hostile place we could have found it."
White said there is still a lot of work that needs to be done to confirm this hypothesis, "but if it holds up, it could mean life is hardy enough to show up wherever it's even vaguely possible."