Early Microscopic Life on Mars? ... Credit Copyright: courtesy NASA Explanation: Today a team of NASA and Stanford scientists announced the discovery of strong circumstantial evidence that microscopic life once existed on Mars . ... A small fraction of the many meteorites that fall to Earth from space have composition similar to the Martian surface . ... The meteorite containing the evidence landed on Earth 13,000 years ago, but may indicate a life-form that existed on Mars billions of years ago. ...