Roland Piquepaille writes "Scientists from NASA and two U.S. universities are using a 20-G centrifuge machine that can simulate up to 20 times the terrestrial gravity to evaluate the effects of hypergravity on humans. This 58-foot diameter centrifuge has three cabins, one for humans -- limited to 12.5 G -- and two for objects and flying hardware. The goal of these experiments is to reduce the adverse effects that space travel can have on astronauts' physical heath. But by studying the health benefits of exercise on astronauts, the researchers also hope to help the rapidly growing senior population who, like astronauts, doesn't exercise much. Read more for additional details and pictures about this NASA's machine."