All the study says is that their lab yeast survived shock waves and perchlorate levels similar to those on Mars.

That's all.

I think by "survive" they mean that yeast spores can briefly be put in a "mars jar" and then be revived, not that they can become metobolicaly active, or even last for an extended time on mars

We should be dropping bags of extremophile organisms into the Martian atmosphere to get a start on terraforming it.

How likely is it that we have already accidentally "contaminated" other planets or moons, despite procedures to prevent this?

It seems unlikely to be possible to completely prevent all lifeforms from hitching a ride

Yeah, we can make beers on mars!

At the end of the day, there are tons of organisms, many of which can survive epic conditions. My personal favourite is still Deinococcus radiodurans but there are many other contenders.

This here is odd because it seems to follow a "life must be everywhere". I never understood this. Aka NASA wants to find life elsewhere, but ... why? Life is already here and evolution occurs. See dinosaur. So, adaptability is an intrinsic property. Why does it have to be shown that yeast can adapt to martian conditions? Do we want to grow yeast on mars? And if the question is humans on mars, why would yeast matter? The conditions do not allow humans to live on mars, unless sheltered. Even genetically modified humans will most likely not be able to live on mars freely. The temperature alone makes this impossible:

https://en.wikipedia.org/wiki/Climate_of_Mars#Temperature

You'd need to be in a suit all of the time or in some building with higher temperature. Mars is not Earth. What is the point of having some bacteria or yeast on mars?

What about uncommon yeast?

So send the yeast.

And yet the stuff in my freezer went bad.

Given that the "percentage of stars with planets" part of the Drake equation has recently been determined to be close to 100%, Panspermia is starting to feel more and more likely.