[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.