[lywald]

Putting viable life on Mars would be such an important threshold. It would guarantee life to survive even the destruction of Earth. Important stuff. Like Raid1 for data redundancy.

Not many things could destroy both Earth and Mars, except the expanding of the Sun in 5 billion years and maybe the fusion Andromeda/MilkyWay in 4 billion years if we're not lucky. Also aliens.

[zerostar07]

Isn't that dangerous though? Could altering its atmosphere have a destabilizing effect? What if they evolve too fast and turn against us?

Edit: interesting to read: http://en.wikipedia.org/wiki/Terraforming_of_Mars

[freehunter]

I think the dangerous part would be altering the planet to be unlivable to the current inhabitants. Which is a good reason for conducting these tests, to see if anything is there before we start transplanting life. If nothing is there, then we can move lichens etc without fear of contamination. If something is there, we don't want to destroy its habitat by introducing new life.

[eru]

Evolve fast enough? We are talking about millions of your earth-years at least. And we don't even know how likely intelligent life is at all. After all, earth only produced one tool-using, technology loving species.

(Dolphins and some others seem smart, too, but they wouldn't venture to other planets.)

[clavalle]

And what? Make it unsuitable for life?

If something happens and they do evolve fast enough to pose a threat, perhaps they will evolve fast enough to realize that two planets with intelligent life are better than one.