Strong, but with a soft touch

Dextre on the exterior of the American Destiny laboratory of the International Space Station (ISS) in 2008.
(Credit: NASA)

The International Space Station (ISS) was designed for easy upkeep over the course of its lifetime. Most of the more standard equipment required to keep the Station's various systems running (like batteries, computers or switch boxes) are pre-packaged in boxes that can be changed with minimum effort when they need repairs. These are known as Orbital Replacement Units (ORUs). Until recently, all the external maintenance on the ISS was done by astronauts—a task that requires a great deal of their time and preparation, but is also very risky.

Dextre's job is to reduce the risk to human astronauts by relieving them of routine chores that need to be done in the harsh environment of space. As Dextre's name implies, the robotic handyman is equipped with special features that allow it to stand in for spacewalking astronauts and perform tasks that require dexterity, accuracy and the sensitivity to know, for example, how much force to apply (something humans do instinctively, but which doesn't come naturally to robots!). Dextre's "hands" are equipped with special force moment sensors that give the robot's computers the ability to detect how hard it should push or pull, and in what direction, within millimetres of its target (imagine pulling out a drawer in your kitchen cupboard and sliding it smoothly back into place without jamming it).

Typical tasks for Dextre include installing and removing smaller payloads (such as 100-kg batteries used on the Space Station), opening and closing covers or reconnecting cables—exactly the same kind of odd jobs the average handyman does daily here on Earth. Dextre can also be used as an on-orbit robotics platform for scientific experiments like positioning new telescopes above the ISS and trying out new tools.

Dextre's hands.
(Credit: NASA)