A reason to go to Mars

From: sailor.barsoom

> I find it interesting that 0.1% of Phobos could build ten
> Island Threes. That's enough to house one hundred million
> people in comfort, and at any gravity level from zero-G to
> one G (including Martian gravity, if desired).

And also Earthly levels of sunlight. They would simply make their mirrors somewhat bigger, and slightly concave, to concentrate solar energy to the levels we're used to. This is a solution that won't work for surface colonies because of the impracticality of such flimsy mirrors in the presence of gravity and weather.

> So a full percent of Phobos would be enough to house a
> billion. Seven percent and you've got room for more
> people to live in comfort and affluence than currently
> live on Earth, in conditions ranging from squalor to
> splendor. Seven hundred Island Threes, at any gravity.
>
> OK Mars advocates, how long until there are one hundred
> million (or a billion, or seven billion) people on the
> surface of Mars?

I go through some simple calculations like this in one of my articles (http://writings.mike-combs.com/case_spc.htm):

A completely terraformed Mars would give us approximately the land area of the Earth. Earth is much bigger, but is mostly covered with oceans. If oceans are desired on Mars (or if they turn out to be necessary to sustain an Earth-like global climate), then deduct accordingly.

We earlier stated that only an orbital settlement construction program which resulted in new land area equal to that offered by Mars should be compared to a Mars terraforming project. Is it really possible to build this many space communities? Can they be built on a time scale competitive with terraforming?

Let's do some simple calculations. The 1975 NASA-Ames study resulted in a space habitat design known as the Stanford Torus. It was designed to provide 670,000 square meters of living space. The surface area of Mars is around 145 million square kilometers. Let's assume no Martian oceans, and ignore the fact that even on a totally Earth-like Mars the polar regions would certainly remain inhospitable. In this comparison, Mars roughly equals 216 million Stanford Toruses.

NASA's study indicated that the first independent orbital habitat could be completed 22 years after initiation of the program, and that a habitat could build a duplicate habitat in 2 years. Let's conservatively assume it'll take 50 years to build the first one, and assign 5 years to the doubling time. We'll also ignore the possibility that the more space communities we build, the better (and faster) at it we'll get, as well as the efficiencies which might be later gained by building smaller numbers of larger habitats with greater land area.

By the time we had achieved 28 doublings, we would have begun to exceed the total land area of Mars. By the pessimistic timetable above, this would take 190 years. (Please note it's not being predicted that this will indeed be the actual growth rate seen, merely that this is the maximum rate allowed by technological constraints.) It's the rare terraforming proposal that's optimistic enough to promise a Mars made over in Earth's image in less than two centuries. Another important point is that near the beginning of the O'Neill settlement construction program, the workforce begins enjoying living conditions that may be even more Earth-like than those possible on Mars only at the very end of the terraforming effort.

Lest it be argued there's not enough raw material available to build this many orbital settlements, the resources of the asteroid Ceres alone would allow us to do this five hundred times over. Space habitats represent an incredible economy of mass in comparison to planets.

O'Neill was interested in shattering the limits to growth which were widely (if somewhat incorrectly) perceived in the 1960's. He once calculated that even if we limited ourselves to the resources of the asteroid belt (merely the most convenient source of materials, and not the only one), we could still build, in the form of orbital habitats, over 3,000 times the livable surface area of the Earth.

Thus, Mars holds out the promise of becoming home to a planetary civilization which might rival that of Earth. Orbital colonies can form a space-based civilization that far surpasses Earth's in both size and diversity.

Regards,

Mike Combs