This image shows the front sides of three rovers viewed at an angle. On the right is the Mars Science Laboratory rover, which is the size of a small sport utility vehicle. Its 7-foot-long arm is extended in front of it, resting on the pavement. The camera 'eyes' at the top of its mast are turned downward at its smaller predecessors. In the middle, the tiny, wagon-size Sojourner rover has a deployable, alpha-particle X-ray spectrometer and single-color camera attached at its rear. On the left, the dune-buggy-size Mars Exploration Rover has its robotic arm extended in front of it, resting on the pavement. The panoramic camera 'eyes' at the top of its mast are turned upward, as if 'looking' at the bigger Mars Science Laboratory rover. All three rovers have six wheels, rocker-bogey suspension systems, rectangular bodies, solar panels, and antennas pointing upward from their spacecraft decks.

Full Size Image

Mars rovers appear to be shrinking with age! The biggest, baddest, newest rover being built is the Mars Science Laboratory rover (right). It's the size of a small sport-utility vehicle. Still exploring Mars four years after landing are the dune-buggy-sized rovers Spirit and Opportunity (left). The first-generation rover, Sojourner, is the size of a microwave oven.

Why are the rovers getting bigger? The answer is one word: science. The mass and volume of science instruments -- tools the rovers use to study the Martian surface and environment -- have remained fairly constant at about 10 percent. To determine if Mars ever could have supported life, the Mars Science Laboratory rover will travel farther, carry more instruments, and sample more rocks and soils than ever before. Like a car with more gizmos, the newest robotic beast has to evolve to carry all the gear!

Image Credit: NASA/JPL-Caltech

You Might Also Like