What mechanism do you propose to "tell us which mutations will occur over time in that environment"? Something like the one we're currently using? It might not go well. Again.

The number of upvotes seriously saddens me. You guys really want to go full My Lai on the other planets?

I wonder what would happen if an organism or virus that was never seen on a planet started spreading?

Consider for a moment what happened when Europeans started making extensive contact with natives in the Americas. Now extrapolate that to the scale of an entire ecosystem, and note the serious ethical issues involved. Or, you know, just look at Australia, the introduction of just three species there (the cane toad, red fox, and european rabbit) has completely upended parts of the native ecosystem, and that’s just looking at land animals.

"Surely it would also be valuable to manually seed life across the universe". That's hardly an obvious conclusion to reach.

No special mutations will occur on Mars just because it's Mars. A mutation occurs randomly when some piece of the DNA string gets a little corrupted. This happens regardless of the location, although a high radiation environment such as Mars would perhaps cause it more often. Which mutations survive would be more relevant.

@JonathanReez We certainly don't expect intelligent extraterrestrial life in the solar system. But not expecting it and being able to prove it doesn't exist are quite different. One day I'm sure we'll be able to give a definitive answer, but not today.

@JonathanReez I don't see any answers mentioning it, so maybe I'm misunderstanding, but Earth microorganisms might wipe out alien life, and causing an extinction is seen as bad thing.

@AndrewMorton in our current ethical system extinctions are only bad if done to creatures possessing neurons (so at least something as complex as a fly). We generally don't worry about wiping out bacteria/viruses.

It's considered "anathema" for the same reason that banging climbing bolts into rock faces anywhere you like just because you feel like doing it is also "anathema" - but on a different scale.

@alephzero do you imagine trad climbing is more popular amongst the bacteria on Mars? :)

@JonathanReez “in our current ethical system” Which system do you mean? and citation seriously needed.

@wizzwizz4 some scientists believe that insects can experience pain. I don't believe anyone seriously considers bacteria or viruses to experience pain. And in most belief systems on this planet, experiencing or not experiencing pain is a critical factor in whether or not a given creature needs to be protected from unnecessary harm. Now, I do accept that we could instead have an ethical obligation towards future humans to let them figure out the mysteries of the universe, but not towards the bacteria themselves.

@JonathanReez Which makes no difference to extinctions. You can cause an extinction without harming any of the members of the species involved (in theory) beyond just encouraging a < 1 repopulation rate and waiting for them to die, but that's generally considered bad.

@wizzwizz4 yes but even in the case of extinctions I've at most seen arguments around the preservation of plants or mushrooms, so multi-cellular organisms. Small single celled bacteria/viruses (the only kind of life possible in Solar System) are never a concern. But again - this has nothing to do with the imperative to satisfy scientific curiosity and letting future humans discover the wonders of the universe.

@JonathanReez We have no particular reason to believe all possible life in the Solar System has to be cellular, let alone unicellular. (And viruses can't self-replicate; they're parasitic,so no they couldn't survive on their own while being considered viruses.) You're making a lot of bold, wrong assumptions.

@wizzwizz4 we do based on life in extreme environments on Earth, which is always very simple. And we do know that non-extreme environments are exceedingly unlikely to exist anywhere in our Solar System.

@JonathanReez For Earth life. Who says astrobiology has to be DNA-based (if it exists)? See also.

@wizzwizz4 please add an answer on this question. Thanks.

@CarlWitthoft: The people upvoting this question most likely just find it interesting or thought-provoking. I see literally no reason to assume that they support massacring innocent people.

@CarlWitthoft voters are not voting about correctness of the question or it's assumptions. The question is useful.

@ruakh That's possibly true, but my point is that nobody with the slightest understanding of biology, or science in general, let alone morality, would need to ask such a question.

@JonathanReez You say it might be possible for there to be life in the Solar System that is not cellular. Has anyone proposed a possible form of life, capable of self replication, that is not cellular? If so, do you know of any links. I would find that fascinating.

@Vince49 I think you meant to ping someone else :)