I was reading a post at New Scientist about preserving Mars a while ago, and I thought it seemed pretty interesting.
When we start colonizing the moon, Mars, and beyond, what responsibility do we have to preserve them as they are?
For example, take Mars. Terraforming it (assuming we have the capability by then) will do more than just add life. Many of its most distinctive features would not exist in a terraformed world, or at least not for long. Its enormous canyons would be filled with water. Erosion would begin beyond the small amount caused by sandstorms. Many of its mountains and volcanoes would become islands or submerge completely.
As the planet heated, frozen water in the ground (permafrost mostly, I guess) would also melt, permenantly changing even landscapes not being flooded. Its polar caps would shrink greatly, too. Its soil would begin to change, no longer the distinctive rusted red we associate with the planet.
And what if there were life there? What if Mars had bacteria deep underground that spreading terrestrial bacteria outcompeted and eliminated? Not only would we lose an amazing scientific opportunity, but we would have destroyed the first alien life we ever encountered. Think about what that would mean, for a moment. What lengths are we obligated to go to in order to ensure that we don’t do such a thing?
Should the goal be to make a second Earth? Should we just change Mars to be a new haven for humankind? Or when we colonize Mars should we become, in some meaningful sense, Martian?
It’s not idle speculation, I don’t think, because it will happen, and probably not so far in the future as we think. But I also think that it’s something that’s very, very important, so it’s not something we should decide immediately. For now, I think, we continue to try to leave Mars as untouched as possible, because we can always start changing it, but once we do, we can never unchange it.