Space Shuttle Discovery carried the humanoid robot Robonaut2 (also known as R2) to the International Space Station (ISS) as part of STS-133. Robonaut2 originally consisted only of a torso, made out of nickel-plated carbon fiber and aluminum. A pair of legs were delivered to the ISS on SpX-3 in April 2014, and they were installed on R2 by station astronauts that August.