Recently it has been suggested that Mars is easy to terraform as well. Meaning that, within a hundred years or so, it could be a place you might live without all that technology. (Or a lot less of it anyway.) As a result I have seen posts all over the blogosphere consisting of different versions of 'Lets go for it!'
My reaction is entirely different. I say 'Hands off!'
Well, reason numero uno: The very things which make easy terraforming possible make life possible. If there is life on Mars then changing the environment to suit us will almost certainly kill it. (Before you make assumptions about how much of a greenie-weenie I am, consider that I do think people come before most critters. Mars is different because there we stand a good chance of killing all of it. Plus there is reason numero dos below...)
Reason numero dos: We don't need Mars. In fact, it makes little economic sense to go there for anything other than scientific curiosity and tourism! Mind you, I'm not talking about a certain recent rant by a beer-addled SciFi writer explaining why space colonization is a just a Heinlein-worshipping nerd's pipe dream. No, I'm talking about gravity wells...
You see, we all live at the bottom of a deep well. It costs a lot of energy to get out of this well, enough that the rant linked above isn't entirely without merit. So, let's suppose we expend that energy; where are we? In an orbit around the sun, that's where. If we want to move to a different orbit it costs yet more energy, although (depending on how much time we have) it costs a minuscule percentage of what it cost to get out of the well. So much less that we can ignore that cost for now and say that changing solar orbits is free.
So we switch to a different solar orbit, let's say that of Mars. At this point we have nowhere to go unless we expend still more energy to go down into a different well! Sure, we can cheat a little and use the atmosphere of Mars to brake us (thereby saving some energy) and doing other stuff like that. But where are we after all that effort? At the bottom of another dang well, that's where!
If we want to go back to Earth we have to repeat the process from scratch. If we want to bring anything back with us we have to pay energy to haul it. There probably isn't anything in the universe so valuable it isn't cheaper to mine or make it here on Earth than it is to ship it back from Mars. (Except, maybe, samples of those unique Martian lifeforms. If there are any.)
Let's recap: We fight our way out of a deep well just so we can climb down into another one. That counts as a definition of stupid as far as I'm concerned.
Does this mean that boozy SciFi writer was right? Well, actually no. He even referred to the alternative, but he didn't apply the same rigor to debunking it. I'm not going to speculate why, except I will assert that I don't think he is blinkered to the same extent certain planetary chauvinists are.
Yup, I called them planetary chauvinists for a reason: They think people would only want to live on planets because that is the only place people have ever lived. I disagree. I think people would like to live anyplace where they can make a comfortable living for themselves and their families. And I think there are approximately 300,000 asteroids which could qualify, even if we have to render them down into space habitats first. Believe me, the asteroids have every resource would could possibly need. And we don't even have to dig deep to reach them.
(Personally I don't recommend hollowing asteroids out to live in. But people have already studied some interesting alternatives, including one kind which you could make by just melting a small m-type asteroid with concentrated sunlight and then blowing it up like a balloon.)
Best part? No gravity wells. Once you are out of this one getting around is cheap as hell. And sending stuff back here to sell is all down hill!
Hands off Mars I say! Down with planetary chauvinism!