"Greg D. Moore \(Strider\)" wrote:

"Tamas Feher" wrote in message
...
all those planets are potential colonies for future colonists.

No planet or other celestial body is inhabitable by homo sapiens sapiens,
unless it has gravity between 80% to 120% of Earth. Gravity is the most
fundamental force in the Universe and lack of enough gravity (less than
0.8G) depletes your bones and muscles, prevents successful reproduction
and
fetus formation. To much and you are flat.

And where exactly did you come up with those numbers?

The fact of the matter is we don't know for sure. We simply know that 1G is
good, 0G is not so great, and know nothing about in between.

It may be .6 G is enough... maybe not.

We don't even know if pregnancy will work in 0G.
Research has been done at high G (centrifuges, with animals living their
whole lives at multiple G (chikens get real meaty legs)) and 0.999G at the
tops of mountains, but there is little data below that.

There may be a "magic" G level at which everything works OK.
It's be nice if this was under 1/6th G, to allow moon colonies.

It may be rather more complex and the G needed varies with age (up to
18 or so) and for some of it a few hours a day at higher G will be needed.

Confining pregnant women in centrifuges, even rather large ones is
technically possible.
Interesting questions arise about inner ear development in a centrifuge.

We need some testing on animals.

Testing at under .999 or so G is hard, as you've got to go into space
to do it.
To do true tests of gravity fields, you've actually got to go to other
celestial bodies.
However, big centrifuges will probably do OK.