For robotic arm training, the astronauts use several different simulators, with each possessing its own strengths. The Shuttle Engineering Simulator (SES) and the Shuttle Mission Simulator (SMS) are two computer simulators that are used extensively. Each one has actual switches and hand controllers to manoeuver a computer model of the arm and the payload. Another heavily used simulator is the Mission Development Facility (MDF). This simulator utilizes real hardware, which includes a hydraulic robot arm, payload mock-ups, and cameras. To assist EVA operations, the NASA Neutral Bouyancy Labortory (NBL) has an underwater robotic arm. This is used to train the crew in joint EVA and arm operations.

The Long Response:

Although gravity cannot be "seen", we do have to account for it in our robotic simulators. For robotic arm training, the astronauts use several different simulators, with each pocessing it's own strengths. The Shuttle Engineering Simulator (SES) and the Shuttle Mission Simulator (SMS) are two computer simulators that are used extensively. Each one has actual switches and hand controllers to manoeuver a computer model of the arm and the payload. The camera views and window views are computer generated graphics of the payload used for that particular mission. Each simulator models the correct arm dynamics and boom flex, so that the astronauts learn how the arm will respond to inputs and stop commands.

Another heavily used simulator is the Mission Development Facility (MDF). This simulator utilizes real hardware, which includes a hydraulic robot arm, payload mock-ups, and cameras. The switches and controls are nearly identical to the real arm, but the payloads that are picked up are volumetrically equivalent to the real payload. The MDF arm can only pick up 500 lbs, so many large payloads like HST are actually large helium balloons. The MDF gives the crew the "real" perception by using actual cameras and window views instead of computer generated graphics.

To assist EVA operations, the NASA Neutral Bouyancy Labortory (NBL) has an underwater robotic arm. This is used to train the crew in joint EVA and arm operations.

On earth, the real arm could not support it's own weight and could not be lifted out of it's own support pedestal with it's own power. For testing of the flight arm, it is placed on an air-bearing floor with high pressure air "pads" that lift the arm onto air pockets (much like an air hockey table). This is not done for training, but only for flight arm testing, as the arm can only be manoeuvered in two degrees of freedom. While the real arm can lift up to 65,000 lbs in orbit, it cannot lift it's own weight on earth. Gravity is an amazing thing.