I’m more concerned what happens when we bring some microbes from Mars.

Andromeda Strain makes a good story, but viruses and bacteria tend to evolve with their hosts and environment. It is unlikely that any virus or bacteria brought from mars would have a serious impact on humans or our environment. We probably aren't good hosts to something that's been evolving in martian conditions.

Interesting, maybe they plan to never bring anything to Earth's surface .. maybe use ISS as an 'air gap'

things that go to mars tend to stay there

That's changing very soon.

Perseverance's mission includes collecting and storing samples for a return mission. https://en.wikipedia.org/wiki/Mars_sample-return_mission

And also things that have gone to Mars in the past have blasted off chunks of Mars into Earth.

We probably have done this already, with the man made machines that we had sent. Although the NASA tries to sterilize the robots/rovers, I doubt that they can kill every bacteria and some of the bacteria are known to somehow survive when exposed to space as well.

Earth bacteria require liquid water (amongst other things). Thus far none of the rovers have landed in a lake, so it's unlikely that earth bacteria will be spreading any time soon.

I've been curious about this recently actually. What are the downsides of "seeding" a plant with life to study how it evolves?

Evolution takes a long time. And there aren't many (any) environments that we've identified and can reach which are conducive to the sort of life we know about. Also it'd be a bit presumptuous for us to colonize a hospitable planet for our own experimentation.

But it's an interesting question. In fiction, I can recommend Adrian Tchaikovsky's Children of Time, and sequel Children of Ruin.

Both great books and a really interesting thought process on what truly alien life might be like instead of just humans with more or less arms.

And thank you as well

Just finished reading the second, I really enjoyed them.

Thanks. Just picked up the first one on Audible!

It becomes much more difficult to determine whether the planet contains indigenous life once you've introduced life from Earth.

i think it's safe to assume it doesn't. And a few plants in a tiny section of mars will hardly ruin the evidence anyway.

What makes you think it’s safe to assume that Mars has no life?

a) simple maths; what are the chances?

b) we should have found something by now. There clearly isn't a whole lot happening on the surface of mars at any rate

a) nobody really knows the chances of abiogenesis or in-system panspermia yet.

b) we’re still guessing at bio-signatures; all we are confident of is there isn’t “a lot of stuff like us”, but that’s a compound claim and we can’t rule out “a small quantity of stuff like us” or “as much life as a desert but very different to us”.

The fear I read is that we might be accidentally eradicating any life we don't yet know about, if we introduce life from earth.

Don't we already to this on Earth?

Yes, but it’s not helpful for research.

Imagine if an alien lifeform had terraformed earth this way. We would not have existed.

(There is a hypothesis that life may have been introduced this way to earth, known as the Panspermia Hypothesis https://en.wikipedia.org/wiki/Panspermia)

There are so many chance events that could have gone differently and we would not have existed.

If not for an asteroid, the earth might still be populated with dinosaurs. Would they have evolved to our degree of intelligence and civilization? Who knows?

    The universe may
    be as great as they say,
    but it wouldn’t be missed
    if it didn’t exist.”

-Piet Hein

I'm also a fan of this idea. It seems far easier than trying to plant humans in giant bubbles with an Earthly ecosystem that just happen to be on the surface of Mars.

As other commenters have noted, it's probably not very wise, but I imagine it would be the cheapest way to increase the chances of the continuation of life (as we know it).

But why would we want to continue life? Whenever I read something like that I feel life a sociopath but I don't really understand it. I'd care about the wellbeing of the people, not the continuation of the human species or, as here, of life itself.

I mean, I think it's kind of a natural reaction to "well if humanity disappears altogether, what was the point?", so we feel an urge to perpetuate humanity, in order to imbue our own existence with some sort of meaning.

Thank you for your answer. So maybe my lack of such an urge it's not about me being a sociopath or not, but a difference in philosophical views. Although gp was talking about perpetuating life itself, not humanity. Does knowing that a random organism somewhere far away it's keeping the metabolic torch lit satisfy this urge?

Maybe after initial terraforming you could also seed it with a specially engineered retrovirus to help evolution along by tweaking genes associated with prosociality.

Means it’s hard to tell, if we find life there later, if that life was native or if we put it there.

Evolved life will come back and may outcompete original life.

What's more important: knowing if Mars had/has life on it or having life on it?

They’d die. For some reason the ‘beneath its surface’ part of the headline got left off this submission.

The surface of Mars is an anoxic toxic irradiated frozen desert.

Most likely we'd be able to determine they are from earth from their properties and from their locations and from their small numbers ?