NASA/JPL

NASA's Mars rovers have accomplished a whole lot since the first one landed on the red planet in the late '90s, but even the latest members of the fleet still have plenty of limitations. For one, they're very slow; Perseverance, which NASA considers a "standout," achieves a top speed of just under .1 mph on flat ground. On top of that, the rough terrain is hard on the rovers' wheels, and steep slopes with hazards like rocks and sand pose a real challenge, sometimes requiring long detours to reach certain targets. But this week, NASA showed off its progress on a prototype that boasts more advanced capabilities: the Exploration Rover for Navigating Extreme Sloped Terrain, or Ernest.

The space agency has been testing Ernest in the Colorado Desert, exploring new approaches that could be used for future missions on Mars and the moon. Ernest has four wheels, in contrast to the current Mars' rovers' six, and is four feet long, though a version that would be used for an actual mission would be double the size. And, it can individually lift its wheels to step on or over obstacles. In the recent tests in the desert, the prototype drove for a total of over 37 hours across seven days, covering roughly 16 miles, according to NASA. It hit a top speed of about .6 mph.

"You could do a science road trip across the Moon — or Mars — with this vehicle," said James Keane, a JPL planetary scientist working on lunar missions. Going back to NASA's Sojourner rover, the Mars rovers have relied on a passive suspension system, the rocker-bogie system, to keep the weight constant across their wheels. Now, though, engineers are trying out active suspension with Ernest to achieve greater mobility. "Two powered joints in front articulate a gimbal that allows the rover to drive using different gaits like squirming, wheel-walking, and obstacle-climbing," NASA says.

It can switch between active and passive suspension depending on the task and energy needs, and thanks to its four steerable wheels, it can drive in any direction. There have already been multiple iterations of the Ernest prototype since the program began in 2022, and the team has tested nearly a dozen active suspension configurations. The latest version also has "enhanced independent decision-making capabilities." The goal with Ernest is to develop the technology for rovers that can cover more ground than those that came before them, and faster, with less reliance on human controllers back on Earth.