Unlike human arms, which move simply by contracting and relaxing muscles, robotic arms use gears, hydraulics, and other expensive, heavy, power-hungry parts. In spaceowhere robots will carry out sample collection and repairs in many nasa-planned missionsosuch complexity becomes a problem.
Heavy items cost more to launch, and power supplies are limited on space probes.
All this motivated Yoseph Bar-Cohen to try to make a better robot. And he may have succeeded. He has created artificial muscles that quickly respond to small amounts of electricity by lengthening or bending, almost like the real thing. Robotic muscles flex and grasp a rock. Bar-Cohen, a physicist at Caltech's Jet Propulsion Laboratory, has made two different types of artificial muscles.