Neil Armstrong sent mankind leaping through the stars, but if a new robotic explorer makes it into space, we may soon be hopping instead. Called the Highland Terrain Hopper, or HOPTER, the vehicle will use hopping—instead of driving—to explore the surface of other planets. Most of this work is currently done by stationary lander platforms or wheeled rovers, which can travel many kilometers. Both have limitations: Landers cannot investigate areas beyond their immediate surroundings, and the more mobile rovers don’t work in ultra–low gravity environments, where their wheels won’t adhere to the ground (like on asteroids, comets, and the martian moons). Rovers are further limited by difficult-to-cross landscapes; this makes studying mountainous terrains challenging, depriving us of key insights into the geology of other planetary bodies. To solve these problems, a team of engineers and planetary geologists decided to design a vehicle with a very different form of locomotion-hopping. Hopping is a highly efficient way for robots to navigate around, through, and over obstacles far larger than themselves. Although the HOPTER is not the first exploration vehicle to hop—the Mars Reconnaissance Lander could make controlled ballistic jumps between flat terrains, for example—the HOPTER’s low center of mass, high maneuverability, and simple, robust design make it the ideal candidate for exploring uneven and mountainous terrain across a broad range of gravitational environments. The HOPTER is still in the design phase, but when it is built, it will feature a 70 cm–diameter reversible disc with three independently firing legs that can project it up to 4 meters into the air on a planet like Mars (see picture, above). With these legs, the HOPTER will be able to precisely navigate up and down steep rock slopes, recover from slips and falls, and even leap over obstacles many times its height. The platform’s relatively light weight means that several could be deployed simultaneously to explore the surface of a planet, allowing for everything from simple picture taking to complex, 3D geophysical surveys. The next step, researchers say, is to develop a working prototype—something they are already getting the bounce on.