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
Transit of Phobos from Mars Lander, moving at about 2 km/s. The shadow was simultaneously imaged from the "Viking 1" Orbiter, which permitted locating the position of the lander in the orbiter pictures. Far more detailed images of the shadow were taken with the arrival in 1997 of the Mars Global Surveyor and its high-resolution Mars Orbital Camera. One such image was taken on 26 August 1999 and shows the shadow at high resolution. This image was featured in a 1 November 1999 NASA press release. By examining maps of Mars we see the shadow is centered at around 10.9°N 49.2°W. We can also look