[wkdown]

I suppose I can understand the argument. I know if/when we find life on another planet or moon (Europa, Titan, etc) that no living matter from Earth should touch that world, for fear of mutating / polluting it. But when it comes to others we either know have no life (Mercury, Jupiter, etc) or most likely don't (Venus, Mars, etc), what is the harm in human exploration or even terraforming attempts?

Even if humans "infected" the whole solar system, how can we spread from there? The Centauri system is the next closest star system [1], most likely without planets there, and is over 4ly away. That's roughly 25 trillion miles away. If we could travel at the same speed as New Horizons (36,373mph) [2], it would still take 77.5 thousand YEARS to get there. [3]

We are not gonna pollute the universe and its a silly to think ourselves capable of such a feat.

[1] http://upload.wikimedia.org/wikipedia/commons/e/e9/Near-star...

[2] http://en.wikipedia.org/wiki/New_Horizons

[3] http://www.wolframalpha.com/input/?i=time+to+travel+24.7+tri...

[pavel_lishin]

The worry isn't about "polluting the universe", it's about contaminating what's basically a big scientific petri dish - Mars. If we start tossing buckets of sludge out there, determining whether there was ever any native life becomes significantly more difficult.

"There are elements trying to keep us from spreading throughout the universe" sounds incredibly paranoid.

[ams6110]

Hard to imagine that any life that formed independently on Mars would ever be confused with life tranplanted there from Earth...... unless life on Earth came from Mars to begin with?

[MichaelSalib]

Perhaps given a full blown xenobiology laboratory staffed with hundreds of the world's top scientists and every instrument money can buy, it would be easy to distinguish earth-borne bacteria from non-earth-borne bacteria. But since we've only got a car-sized rover with a handful of instruments and no scientists on site, we need to be more careful.

In any event, how exactly do you differentiate earth-borne bacteria from non-earth-borne bacteria? What's your rubric?

[AutoCorrect]

dna.