The only thing Mars has in quantity that would be of use to an expanding colony is iron(III) oxide and water ice. We know this because several rovers have analyzed Martian rock, and orbiters have analyzed the Martian surface. But available resources are very important, because the cost of a space launch is exponentially related to the mass of the material you are launching. The more resources you can scrounge locally, the fewer you have to ship, and every gram of material you launch into orbit takes a kilogram or more of fuel.

Luna has zinc, titanium, nickel, iron, cobalt, manganese, silicon, and oxides and hydrides of all of the above, as well as other minerals and metals, plus a possibility of water ice. The only resource the Moon does not have, for sure, is nitrogen and nitrates. All of those resources that can be mined on the Moon are resources that won't have to be shipped to the Moon. Besides, the Moon is closer to Earth and is therefore cheaper and quicker to get to.

What, because that worked out so well? No, imperialism is wrong, even if no-one lives in the land you want to take.

__________________
Trust me, I'm a socialist!

There's power in a factory,power in the land, power in the hand of the worker. But it all amounts to nothing if together we don't stand, there is power in a union.
The union forever defending our rights, down with the blackleg, workers unite. To our brothers and our sisters in many far off lands, there is power in a union.
Money speaks for money, the devil for his own. - Billy Bragg

How many things have we landed on Mars?

How can we really be sure what is there?

__________________
"Have you no decency, sir? At long last, have you left no sense of decency?"
-Joseph Welch

We know that the moon doesn't have any water, in any form. Due to low mass and temp range. Any water that it did have would have been lost into out space (on the sunny side of the moon, any ice would melt, and much would disolve into water vapors, the low mass, which makes low gravity, would allow for all the water vapor to fly into space, so every day, the moon would lose some water vapor, until it had none left.

Transportation would not be a problem between planets. As seeing as we are talking sci-fi~ish, the obvious answer would be a space elevator on each planet. The only energy used is the energy to get out of the pull of the planet, so distance only effects time, not fuel.

I think that Venus would be the best option for colonizing. It is large enough to hold an atmoshpere, has Nitrogen, Carbon, Oxygen, and Hydrogen. Through several not very difficult chemical processes, it would be easy to grow vegitation there in well kept and maintained facilities. Over the course of decades, it would slowly change the enviroment to allow possible outside living.

I've gotta go, I'll get more into that in a moment.

__________________
Set your destination with your heart, get there with your mind.

"The wisest men follow their own direction." - Euripides

Fourteen. Wikimedia Error

They've landed in pretty much all of Mars' major regions, and I don't recall them finding much of utilitarian value. Scientific value? Yes. Utilitarian? Not much.

No utilitarian value? They said that you could grow great asparagus in Martian soil. Now I know that comment was tongue in cheek, but if you are talking about permanent colonies (not just shipping resources two and fro) the ability to grow food is HUGE.

I'm no scientist, but I'm curious as to how they can know exactly what a planet holds by taking fourteen surface smears.

__________________
"Have you no decency, sir? At long last, have you left no sense of decency?"
-Joseph Welch

The soil is good for growing, the lack of water, though isn't.

And fourteen is a good amount. How many times did the bristish come to the "new" world before the colonists did?

__________________
Set your destination with your heart, get there with your mind.

"The wisest men follow their own direction." - Euripides

Not really a legitimate comparison...

__________________
"Have you no decency, sir? At long last, have you left no sense of decency?"
-Joseph Welch

Sorry, a space elevator can't opporate on Venus. A space elevator requires the rotation of the planet to keep it up (the slower the planet's rotation, the longer the cable would need to be), Venus rotates once every 243 Earth days, so the space elevator would have to be about 10 million km, or about 1/4 the distance between Earth and Venus when they are at their closest.

__________________
"The people have always some champion whom they set over them and nurse into greatness...This and no other is the root from which a tyrant springs; when he first appears he is a protector."


"We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light."

--Plato

developing an extraterrestrial colony for mining or other commercial interests is probably different politically to developing it for expansion of the population. a commercial enterprise would have specific backers, a specific purpuse and agenda, it could be temporary and mobile and probably not be much different to, say, an isolated oil rig in an inhospitable part of earth.

a colony for the purpose of expanding population is likely to be different. it would be expected to be larger, independent, fixed, support everyone from newborn babies up to retirement and beyond, be a fully fledged society, at least eventually. politically it would be very different to a commercial venture and likely require its independence and political identity fairly quickly.

also, a commercial enterprise can go anywhere the resources are and leave once the resources are depleted, so the moon, venus, mars, even asteroids are all fair game. a social colony is probably is restricted to mars. the moon lacks the gravity to support an atmosphere, venus is too hot. mars is the most comparable to earth and probably the easiest to develop into somewhere liveable.

beside the economics and politics (and the unanswerable question of technological capability) what are the ethics of terraforming mars ? we are trying to preserve diversity and natural areas on earth, is it ethical to alter a whole planet for our uses ?