Will a four-armed robot replace astronauts in space?

Space changes the rules for almost everything, including how a robot should move. On Earth, legs help us stand, balance and walk across a room. In microgravity, those same legs lose much of their purpose.

That is why Orbit Robotics, an academic spinout from ETH Zurich, took a different approach with Helios. The robot was built with four arms so it can grip, brace and work inside a spacecraft. Two arms can hold on while the other two handle tools, cargo and equipment.

It is a smart...