The Remote Manipulator System (RMS), or Canadarm, is a mechanical arm in the cargo-bay area. A payload specialist can control this arm using the flight controls on the flight deck of the orbiter. The fifty-foot arm has three joints similar to a shoulder, an elbow, and a wrist. Its hand is called an end effector.
The RMS has launched and retrieved satellites, helped repair the Hubble Telescope, removed ice build up from the shuttle, served as a work station for astronauts and docked the Space Shuttle with the Russian Space Station Mir. A total of four arms are being used today. Five have actually been delivered to NASA, but one was lost in the Challenger explosion. The carrying capacity for the RMS today is 29 thousand kilograms, though Canada is working on increasing that to more than 225 thousand kilograms. This increase on carrying capacity will allow the RMS to dock the shuttle with the International Space Station.