No more retro Mars Rovers getting stuck in sand! Presto! NASA's new army of tumbleweed beach ball robots will roll across the Red Planet surveying vast tracts of exotic Martian landcsape surface. Tt's a big, lightweight, two-story tall beach ball equipped with scientific instruments and propelled by nothing more than the thin Martian breeze.
Much of the Martian terrain is sloping and littered with boulders, which makes tough going for most vehicles. But experiments in the Mojave Desert and elsewhere confirmed that 6-meter diameter balls should be able to climb over or around one-meter rocks and travel up slopes 25-degrees and higher in the thin, but breezy Martian air.
Tumblweed is a big, bouncing ball that's light enough to be guided randomly around Mars by nothing but the planet's wind. Wind that's known to be strong enough to create dust devils and polish Spirit's solar panels from time-to-time. With a 20 kilogram ball and 20 kilogram payload, the 6-meter diameter tumbleweed ball is light enough that it could be added on to another lander and deployed from the ground, or it could be in its own delivery vehicle.
A payload carrying instruments such as cameras or a water-seeking radar could be held in place by tension cords at the tumbleweed's center. When it's time to stop for a while, perhaps to study an interesting spot or to wait for the wind to change direction, mission controllers would simply command the ball to partially deflate. Then, when it's time to move along again, the ball could be reinflated to roll on toward new frontiers.
Test designs have already been deployed to harsh Martian-like environments in Antarctica and Greenland, where they successfully traversed hundreds of miles of terrain without incident. These were inflatable designs that had the ability to deflate and remain stationary (to perform experiments), before re-inflating and continuing on.