MARS USED to teem with life, but now it's a dead world. I'm not referring to actual Martian history, which we still know very little about. I'm talking about the way humans used to think of Mars and how the they think about it now. As recently as the 1950s, Mars was packed with scary, incomprehensible creatures and hulking buildings set in a web of gushing canals. But now it's a cold, dry land full of rocks that are fascinating mainly due to their extraterrestrial nature.

We even have two robots who live on Mars, sending us back pictures of mile after mile of beautiful emptiness that looks like the Grand Canyon or some other national park whose ecosystem is so fragile that tourism has already half-destroyed it.

Mars has, in short, been demystified. It's not an exotic source of threat or imagination; it's a place to which President George W. Bush has vowed to send humans one day. And last weekend, a conference was convened at Stanford University to discuss the feasibility of a U.S.-led mission that would send humans to the red planet. The attendees, mostly scientists and public policy types, were all preaching pragmatism.

Reuters reports that consensus at the conference was that NASA would need an additional $3 billion per year to plan for a Mars mission that would leave in the 2030s. (NASA's current budget is $17.3 billion per year.) So the question that geeks like to ask each other—"What would you take with you to colonize another planet?"—now has a depressing and very non-science-fictional answer when it comes to Mars. It's $75 billion, paid out over the next 25 years.

But just to put things in perspective, a congressional analysis done in 2006 pegged the cost of the U.S. war on Iraq at $2 billion per week. Last year, the total amount of money spent on the war in Iraq surpassed $1.2 trillion. So it's a hell of a lot cheaper to colonize Mars than it is to colonize our own planet. Still, it's too expensive.

U.S. aerospace geeks are hoping that we can turn to Europe, Russia and perhaps Asia to collaborate on a Mars mission because nobody is expecting that NASA will ever get even a sliver of the budget that the U.S. war machine does.

There is a tidy way to wrap this up into a lesson about how we're willing to spend more on destroying life as we know it than extending life to the stars—about how we'd rather burn cash on war than healthy exploration of other planets. But that's not the whole story.

Let's say the U.S. government decided to leave Iraq alone, and spend $2 billion per week on a mission to Mars instead, a mission that would culminate in a human colony. We could follow a plan somewhat like the one outlined in Kim Stanley Robinson's book Red Mars, where we first send autonomous machines to create a base and begin some crude terraforming. And then we send a small group of colonists, to be followed by bigger and bigger waves of colonists who eventually live in domes. And who wage wars and rape the Martian environment.

I think the problem with colonizing Mars is that it would look all too much like colonizing Earth. We might even be killing a fragile ecosystem that we're not yet aware of. But most of us haven't demystified Mars enough yet to realize that. Sure, we know it's not packed with cool aliens, but we haven't yet realized that hunkering down on another planet isn't going to solve our basic problems as humans. On a planet, given the chance, we'll exploit all natural resources including each other.

It's not that I'm against a mission to Mars. I just think that getting the money for that mission is really the least of our problems. What I'm worried about is what humans tend to do with money when they aim it at something, whether that's a nation, a people or a planet. Maybe it's better for Mars that we can't afford to go there yet.

Annalee Newitz is a surly media nerd who would rather live on an artificial Halo world than a colonized planet.

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