e next Mars rover, Curiosity, has been outfitted with a new cutting-edge mobility system that's enough to make off-road enthusiasts drool with envy. The rover, which will carry ten times the payload mass of Spirit and Opportunity, is about the size of an SUV, and too heavy for an airbag landing.
It has a set of six wheels that are 20 inches in diameter -- larger than a car tire. Each wheel has its own motor, giving the rover independent six-wheel drive, and "cleats" that provide grip and help keep the rover from slipping when climbing over rocks or sand hills. The rover can also do swerving maneuvers and turn in place a full 360 degrees.
Like the Spirit and Opportunity rovers, Curiosity will have a "rocker-bogie" suspension system, which keeps it from tipping over when rolling over large rocks or hitting dips in the Martian terrain. But unlike the earlier rovers, Curiosity will use its wheels as landing gear when a rocket-powered descent lowers it directly onto the Martian surface via a tether in August 2012. When Spirit and Opportunity touched down on Mars in January 2004, they were cushioned from the bumpy landing by the airbags that held them. But despite the protection, airbag landings introduce additional risks during the egress phase -- the period of time between the actual landing and driving the rover off the lander onto the Martian surface. Egress involves a series of tactical moves and steps, so the flight team must give the rover commands and assess the resulting data before proceeding with the next step.