A robonaut is a humanoid robotic development project conducted by the Dextrous Robotics Laboratory at NASA's Lyndon B. Johnson Space Center (JSC) in Houston, Texas. Robonaut differs from other current space-faring robots in that, while most current space robotic systems (such as robotic arms, cranes and exploration rovers) are designed to move large objects, Robonaut's tasks require more dexterity.
The core idea behind the Robonaut series is to have a humanoid machine work alongside astronauts. Its form factor and dexterity are designed such that Robonaut can use space tools and work in similar environments suited to astronauts.
The latest Robonaut version, R2, the first US-built robot on the ISS, delivered by STS-133 in Feb 2011, is a robotic torso designed to assist with crew EVA's and can hold tools used by the crew. However, Robonaut 2 does not have adequate protection needed to exist outside the space station and enhancements and modifications would be required to allow it to move around the station's interior. NASA states "Robonauts are essential to NASA's future as we go beyond low Earth orbit", and R2 will provide performance data about how a robot may work side-by-side with astronauts.
Work on the first Robonaut began in 1997. The idea was to build a humanoid robot that could assist astronauts on tasks in which another pair of hands would be helpful or to venture forth to perform jobs either too dangerous for crew members to risk or too mundane for them to spend time on. This system wouldn't need specialized tools and would be able to use the same ones as the astronauts. The initial design of Robonaut was for it to be used as an end-effector for the robotic arm on the International Space Station, where it could serve as an alternative to human extravehicular activity for external maintenance on the station.
Robonaut 1 (R1) was the first model. The two Robonaut versions (R1A and R1B) had many partners including DARPA. None were flown to space. Other designs for Robonaut propose uses for teleoperation on planetary surfaces, where Robonaut could explore a planetary surface while receiving instructions from orbiting astronauts above. Robonaut B was introduced in 2002, R1B is a portable version of R1. R1 had several lower bodies. One of these was the Zero-G Leg, which if Robonaut was working on the space station he would climb using the external handrails and then use his zero-g leg to latch onto the station using a WIF socket. Another was the Robotic Mobility Platform (RMP), developed in 2003, it is a base with two wheels using a Segway PT. And the four wheeled Centaur 1, which was developed in 2006. Robonaut has participated in NASA's Desert Research and Technology Studies field trials in the Arizona desert.