Life on Mars If the surface life has been reanimated as recently as 450,000 years ago, then rovers on Mars could find dormant but still viable life at a depth of one meter below the surface, according to an estimate. In 1965, the Mariner 4 probe discovered that Mars had no global magnetic field that would protect the planet from potentially life-threatening cosmic radiation and solar radiation; observations made in the late 1990s by the Mars Global Surveyor confirmed this discovery. Scientists speculate that the lack of magnetic shielding helped the solar wind blow away much of Mars's atmosphere over the course of
Space probe far layers of our heliosphere, thus concluding the craft had broken beyond the heliopause. Voyager 2 was launched by NASA on August 20, 1977. The probe's primary mission was to visit the ice giants, Uranus and Neptune, which it completed on October 2, 1989. It is currently the only probe to have visited the ice giants. It is the fourth of five spacecraft to have left the solar system. It has been operational for 41 years and 2 months as of October 20, 2018. Cassini–Huygens was a 5,712kg (12,593lb) space probe designed to study gas giant Saturn, along with its