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From: Collin R. Skocik [mailto:acclarkefan2001@verizon.net]

> But assuming Mars can be terraformed, which I think
> it can be relatively easily within half a millennium
> (some of us may be around to see it!),

Wow, sounds like you're anticipating some pretty radical advances in
longevity!

I think here is another area where O'Neill's concepts remain more
attractive than the planetary settlement scenario. We might could get a
Mars base going on a relatively short timescale. But for permanent
settlers, I think Mars could only offer a lifestyle comparable to living
out in the open here on Earth at the end of the terraforming process.
Orbital settlements could offer even more Earthlike conditions
(including "gravity" and sunlight levels) on a much nearer timescale.
NASA's Space Settlement study concluded that the first habitat could be
completed 22 years after beginning the project. Keeping in mind that
"everything takes longer and costs more", the real answer might be
closer to 30-50 years. But even if so, that's a timescale about 1/10th
what you proposed for Mars terraforming, and is inside the lifetimes of
humans at present-day longevity levels.

> certainly living on the surface of a pressurized planet
> will be more permanent and more easily maintained than
> living aboard a space station.

It would depend on how permanently you engineered the orbital structure.

> Gravity is only a third of Earth, but humans can adjust
> to that -- even rotating space stations will probably give
> us Mars or Moon gee.

CAN give us Mars or Moon gee if that's what we want, but not NECESSARILY
those lower levels of gravity. If it turns out that those lower levels
of gravity are no problem, than we can have that in orbital structures,
and engineer at a smaller scale. But if our luck should come up short
in this area, and we find via experience that nothing short of a full 1
G of gravity will prevent serious health issues, then we can provide
that via rotation.

> Some denitrifying bacteria, some clever hydroponics and
> agricultural development and in time, Mars won't require
> continual supply runs from Earth, thus eliminating the need
> for constant space launches

In my opinion, neither proposal can fly without elimination of virtually
all needs for material resupply from Earth. Closed ecologies can be an
advantage for orbital habitats as well as for planetary ones.

> If disaster were to strike a planetary colony on a
> terraformed Mars, the inhabitants would have almost a
> guarantee of survival, while inhabitants on a space station
> would have virtually no chance.

What kind of disaster are you thinking of?

I've considered the disaster of a major asteroid strike. First, it's
important to make valid comparisons. So we shouldn't compare the entire
planet of Mars to a single space habitat, but instead to a swarm of
habitats with land area equal to that of Mars. An ELE would be the same
bad news on a terraformed Mars as it has been on Earth, and for the same
reason: a planetary ecology is an interconnected whole.

Now imagine that same asteroid tearing through an orbiting ring of 216
million Stanford Tori. Those in the direct path of the asteroid would
become incandescent vapors. Many very close to the path would sustain
catastrophic impacts from sputtering debris. But any habitat just a few
miles out of the direct path of the asteroid would get by completely
unscathed.

A Martian living even on the opposite side from an ELE would at the
least have to contend with the ecological upheaval.

> A space station is a temporary setting, in my opinion,
> and unless there's a fundamental step forward in our
> ability to contruct space stations, will always so remain.

I think you're making a correct argument, but only for carefully
choosing your terminology to make it true. You keep saying "space
station"; and for that term, I'm sure you're right. But I don't think
permanent settlements on Mars should be compared with present-day space
stations but instead with permanent space habitats.

> By the way, Mike Combs, your name is very familiar. I see
> you've written articles -- what magazines are they in? Any books?

I've never been paid for my writing. If you're a member of the Space
Frontier Foundation, you might have seen a couple of my articles in
Space Front, but that would be about it.

Regards,

Mike Combs