Is WALL-E our A.I. future? Billionaires in orbit above dead earth?

[Justice matters.]

9. Bones decay in space.

In the microgravity environment of space, astronauts lose on average 1% to 2% of their bone mineral density every month. For a short-duration flight, bone loss is a fairly minor consequence. On a long-duration space flight, such as those planned for missions to Mars and beyond to Europa, bone loss could become a serious impediment.