This little NASA rover can conquer sand and steep hills

After six years of exploring the plains of Mars, NASA’s Spirit roverwas brought to a halt in May 2009 when it got stuck in soft soil near the Gusev crater. Though scientists made many attempts to free the rover, it was unable to escape and researchers terminated the mission entirely in 2011. To avoid Spirit’s fate, researchers now know that future rovers will need to be able to move about in new ways to navigate rugged terrain like the Moon’s icy poles.

Fortunately, researchers at NASA and the Georgia Institute of Technology have recently devised a way for rovers to scoot over loose soils without getting stuck and even climb up steep hills without stalling. Using a miniaturized version of a scrapped rover design, they found that a combination of walking, paddling, and wheel-spinning allowed the vehicle to crawl through beds of poppy seeds and wet sand. The team reported the findings on May 13 in the journal Science Robotics.

“The work described in the paper represents a hybrid approach to mobility,” William Bluethmann, an engineer at NASA’s Johnson Space Center in Houston and coauthor of the new paper, said in an email to Popular Science. During a mission, the rover would spend most of its time rolling about on wheels, but “during the uncommon, bad day when a rover finds itself in material where it’s too soft to rove,” the vehicle would deploy this unconventional new gait.

Much of the surface of the Moon and Mars is covered in soft, loose soil called regolith. The wheels on traditional rovers aren’t ideal for locomotion in this grainy, unstable substrate. “In a soft soil you get deeply buried and can’t climb out of your own little pit that you’ve created,” says Daniel Goldman, a physicist at Georgia Tech who also worked on the project. “Wheeled vehicles are really good on hard ground, but when you get to more complicated terrain you need more flexible and multifunctional appendages.”

When designing a prototype for the later-scrapped Resource Prospector 15 (RP15) rover, NASA researchers gave the vehicle limbs that could make lifting and sweeping motions in addition to spinning and rotating their wheels. The rover was intended to visit the lunar poles, where loose regolith, steep slopes, and shadowed craters abound.