Given all the evidence presently available, we believe it entirely reasonable that Mars is inhabited with living organisms and that life independently originated there
The conclusion of a study by the National Academy of Sciences in March 1965, after 88 years of surveying the red planet through blurry telescopes. Four months later, NASA’s Mariner 4 spacecraft would beam back the first satellite images of Mars confirming the opposite.
After Earth and Mars were born four and a half billion years ago, they both contained all the elements necessary for life. After initially having surface water and an atmosphere, scientists now believe Mars lost it’s atmosphere four billion years ago, with Earth getting an oxygenated atmosphere around half a billion years later.
According to the chief scientist on NASA’s Curiosity mission, if life ever existed on Mars it was most likely microscopic and lived more than three and a half billion years ago. But even on Earth, fossils that old are vanishingly rare. “You can count them on one hand,” he says. “Five locations. You can waste time looking at hundreds of thousands of rocks and not find anything.”