>However, current physiological estimates suggest that humans would have to do four hours a day of high-intensity exercise -- in order to counter the known effects of calcium loss from bones (osteoporosis), as well as muscular atrophy, both of which occur when spending extended time in a low-gravity environment. Proper calcium deposition on bones requires the stress of weight-bearing exercise. If we do not develop the ability to put full weight on bones, astronauts' bodies will also suffer brittle calcium loss throughout the duration of the space flight needed to get to Mars.
>
> Wolf "deviner les jeux avec moi à notre club des ignorami" spirit

Artificial gravity. After the Mars shuttle has left Earth's atmosphere, the ship splits into two parts -- the passenger cabin and a counterweight, attached by a chain like so:

o----:----o

Next, you just rotate the two parts around the central part of the chain (the colon in the above diagram). Viola! Instant simulated gravity, no calcium loss.

-Faux "goin' around in circles" Pas