Sony designed its robotic dog Aibo to bark and roll over. The
Jet Propulsion Laboratory designed its robotic rover not to roll
over. That’s harder than it sounds. The challenge, according to
Issa A.D. Nesnas, principal investigator for JPL on this NASA
project, was to make Axel both symmetrical and simple. “We
designed it to be symmetrical because it’s working on rocky,
steep slopes. If it falls off a ledge, or flips upside down, it
can still operate.” That’s where its cylindrical design and
paddlewheel feet come in. But it also uses as minimalist a
design as possible. “If you make it simple and small and
lightweight enough, you can use multiple rovers when you go to
high-risk areas. Because we’re targeting high-risk areas where a
lot of things could go wrong, having multiple rovers manages the
risk for the overall mission.” This means that none of the
components of any one Axel require backup, which keeps the
weight down. The current Axel prototype has an onboard computer,
power system, and wireless communic