Osteoporosis, the most common bone disease, causes a loss of bone mass, which makes bones fragile, brittle, and more susceptible to breaks and fractures. It's often associated with old age (especially in women) here on Earth, but in zero gravity, it affects everyone. Astronauts lose calcium from bones in space, as the body sees no need to keep bones in tip-top shape when they're not supporting the body's weight. It's not osteoporosis, but it has the same effect. Astronauts have been working out with harness and strap-type exercises since the Apollo days, but that doesn't treat the actual loss of bone mass. NASA has created several ways to both detect and treat the bone problem, including new kinds of 3-D tomography scans (which analyze the bone's microarchitecture) and a curious vibrating plate . Yeah, you read that right: NASA scientists think that a certain kind of electrotherapy that requires the astronaut (or regular person) to stand on a "lightly vibrating plate for 10 to 20 minutes each day" while held down with elastic straps could have a beneficial effect on bone loss. Testing is still underway, but is very promising in experiments with lab animals (seen here).