NASA’s past few Mars rovers have been friendly robots with head-like masts and cameras for eyes, easily anthropomorphized and adored. The next generation might be decidedly less cute--they resemble a medieval battle mace.
The Phobos Surveyor is a new concept from researchers at Stanford, MIT and NASA’s Jet Propulsion Laboratory. The spacecraft would visit the Martian moon Phobos, or maybe an asteroid. Then one or more mace-ball rovers would deploy from the mothership (which would stay in orbit above) and leap and tumble across the surface of the moon or asteroid. Marco Pavone, an assistant professor of Aeronautics and Astronautics at Stanford, came up with the idea and nicknamed the hopping rovers “hedgehogs” (definitely a cheerier name than mace balls).
Hoppers are a favored design for future planetary explorers because they could cover much more terrain than a rover, and could easily cross canyons and other hazardous areas. With a hopper, you don't face problems like a stuck wheel, which doomed NASA’s Spirit Mars rover. MIT and Draper Labs have a prototype moon hopper vying for the Google Lunar X Prize: The Terrestrial Lunar and Reduced Gravity Simulator, or Talaris. That one uses ducted fans and compressed nitrogen to hover and hop around.