Free Astronomy Magazine March-April 2021

MARS ROVERS I n this image, Opportunity used its navigation camera for this northward view of tracks the rover left on a drive from one energy-favor- able position on a sand ripple to another. [NASA/JPL] L eft, Spirit acquired this mosaic of an area east of “Home Plate”, in the Columbia Hills. The mosaic shows an area of disturbed soil (the lighter patch) composed by nearly pure silica. It could have come from a hot-spring environ- ment, in which acidic, volcanic steam rises through cracks. Either way, its formation in- volved water. [NASA/JPL-Caltech/Cornell] T his ani- mation features the Mars Explo- ration Rover's entry into the martian at- mosphere and final soft landing using airbags. [Cornell Uni- versity] of years ago, the coast of a salty sea. The rocks that Spi- rit and Opportunity studied showed scientists that the types of water features on Mars could have been very similar to features on Earth. Once upon a time, Mars also had lakes and rivers on its sur- face. Additionally, it also had aquifers and water under- ground, as well as water vapor in the atmosphere. Before landing, the goal for each rover was to travel up to 40 meters in a single day, for