Tardigrades may now be living on Moon (opens in new tab)

Confucious would reply:

When the wise man builds an incredible machine that can bring us to the Moon, the fool looks at the bags of feces.

More seriously, because of the rocket equation, bringing more payload back would require a lot more fuel. Bringing this additional fuel to the Moon would also require even more fuel.

The Saturn rocket is still the biggest rocket ever made. Probably, the engineers back then did not want to make an even bigger one just to bring back the bags.

I assume it's mostly a matter of fuel and how the added weight would've required far more of it.

> Were payload restrictions that tight on the return Apollo journeys?

Probably, yes. https://www.vox.com/science-and-health/2019/3/22/18236125/ap...

Well, they could have, but if they had they would have brought back fewer samples of actual material from the surface of the moon. Given the enormous expense and risk involved in getting there, it's far from obvious to me that they made the wrong decision.

The low "air" pressure, lack of atmosphere, lack of magnetosphere, radiation (including UV radiation from the sun) kinda makes sure it becomes a non-issue in a short time. That's why NASA probably didn't worry about leaving it there too much.

It won't decay biologically though.

I disagree with "Pristine environment", it gets hit with extra-solar-system all the time, as the several marks on its surface attest to it.

From an outside perspective, that waste is probably the most interesting and valuable part of the moon now. And this idea of 'purity' is rather absurd, given the size of the moon. Almost nothing in the universe is so pure that you can't find contaminants on the order of ~1 part per mole. Do you complain when someone leaves a gold atom on a sugar cube?

Before Apollo it is possible that missions like Surveyor 3 were contaminated with bacteria like Streptococcus mitis which may have been found on components of Surveyor 3 returned by Apollo astronauts: https://en.wikipedia.org/wiki/Surveyor_3

Those were turdigrades, different class.

i wonder if they accounted for the reduction in mass when calculating the return trajectory

Yes: they necessarily do so.

Despite the article's statement, tardigrades are not extremophiles, they can't live in extreme environments. What they can do is exist/survive in hard vacuum and other extreme environment by entering a super-hybernation mode (cryptobiosis).

Furthermore while they can survive fairly long spans in extreme environments they're not actually immortal, the FOTON-M3 mission resulted in 32% mortality after 10 days in hard vacuum but protected from UV (the survival rates were much lower for those exposed to UVs).

yes because there is no water, air, or food on the moon for a suitable habitat for tardigrade reproduction

We can sequence its DNA and see how similar it is to the ones on Earth. If there are living organisms on the moon that share a common ancestor with Earth tardigrades then they diverged a very long time ago and their DNA will reflect that. But if their DNA is identical to those on Earth then we know they came from Earth.

yes, these tardigrades were sent to the Moon in a rocket

i agree the article isn't super informative, but is it correct to say that something in cryptobiosis isn't alive? There is almost certainly some tiny amount of remnant metabolism and sensor proteins.