43 years ago, in 1976, the Viking twin probes were the first to land on Mars, providing unpublished images of the planet, as well as an analysis of its atmosphere and terrain.
In addition, they conducted scientific experiments aimed at looking for signs of life on the ground of Mars and, initially, believed they had found it.
This is revealed by Gilbert V. Levin, one of NASA's leading scientists who participated in that mission, noting that the Viking probes on Mars detected the first evidence of biological life outside the Earth.RELATED
In an article published on the Scientific American site, Lev in said: "I am convinced that we found evidence of life on Mars in the 1970s."
The former collaborator of the US space agency recalls that the LR (Labeled Release) experiment showed that the Mars soil tested positive for metabolism. In total, four positive results, backed by five controls.
However, when a new test failed to detect organic matter, the space agency concluded that the LR had found something similar to life, but not life.
In the experiment, Viking probes placed nutrients in the soil samples from Mars. If there were life, it would consume food and leave gaseous traces of its metabolism, which radioactive monitors would detect.
To ensure that it was a biological reaction, the test was repeated after altering the soil, which would be lethal to known life. If there were a measurable reaction in the first and not in the second sample, that would suggest functioning biological forces, and that is exactly what happened, according to Levin.
However, other experiments could not find any organic material and NASA could not duplicate the results in its laboratory, so they ruled out the positive result as false positives, some unknown chemical reaction instead of an extraterrestrial life test.
"Inexplicably, during the 43 years since Viking, none of NASA's subsequent missions on Mars has carried a life detection instrument to follow up on these exciting results," the scientist concluded.
Although Gilbert accepted the opinion of NASA, four decades later he remains convinced that in 1976 they found life on Mars.