Free Astronomy Magazine March-April 2021

13 MARS ROVERS M artian clouds photographed by the Mars Pathfinder (IMP) Im- ager on Sol 16, about forty minutes before dawn. [NASA/JPL] shape and texture of Yogi show that it was probably deposited there by a flood. Another rock, called “Moe,” instead showed signs of erosion caused by wind. Most of the rocks analyzed showed a high sili- con content. Sojourner also visited an area known as “Rock Garden,” where the rover encountered cres- cent-shaped dunes, similar to the crescent-shaped dunes on Earth, which are typically formed by winds blowing in one direction only. cated that Barnacle Bill was very similar to terrestrial andesites, con- firming volcanic activity in the past. After Barnacle Bill, Sojourner ana- lyzed a rock called “Yogi” with the APXS, which turned out to be of basaltic origin, therefore more primitive than Barnacle Bill. The