Putting humans in space

On 2/12/12 5:27 PM, sraj wrote:

> Wrote: But compared to the million tons per second (!) lost by the solar
> wind,
> total spacecraft reaction mass will be a drop in the bucket.
>
> Answer: You are right. But the Sun can afford to lose mass, not tens of
> thousands of space habs. If humans could figure out some way to use what is
> lost by the Sun for the purpose of reaction mass that would be another
> story.

Well, I thought the concern was just the total mass loss of the solar
system. We certainly can use at least some of the solar wind as
reaction mass, e.g., what impacts (and sticks to) the various solid
bodies in the solar system. That's a tiny fraction, of course, but it's
just hard for me to imagine at what point we would ever start feeling
short on mass anyway. (And my imagination is normally pretty able.)

> Answer: 200 billion $ for 200,000 inhabitants works out to one million $ /
> person.

Yes, I slipped a couple digits there... sorry about that.

> OK, let's put the problem in another way. let's first calculate the
> investment required for 200,000 inhabitants to survive in the garden
> environment of the Sahara Desert (it will be a garden environment when
> compared with the environment on the Moon and Mars), what will be the
> required investment?....

I do think this would be a useful exercise -- as you say, the Sahara is
paradise compared to any extraterrestrial environment, except perhaps
for the lack of microgravity and 24/7 sunlight.

I do have some doubt, though, that anyone will ever find that exercise
worth the cost. Unlike a space colony, it's not a stepping stone to a
much larger economic sphere.

Best,
- Joe