Tardigrades may now be living on Moon | Hacker News Reader

Tardigrades may now be living on Moon

afp.com

39 pointsgglon34 comments

Can this be flagged as clickbait? They are not living, they are in cryptobiosis. Even though experiments have shown that they can come back to life after a long time in this state, nothing can guarantee that they are actually still alive.

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.

If we find one on the moon, can we know if it originates from earth?

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

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

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.

Do you know how much tardigrades DNA have changed since they first appeared on earth?

I do not know exactly how much but this is something that can be approximately quantified.

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).

They will be waiting for us when we come back.

Cue the "accidental panspermia hypothesis" - the real (messy) world variant of panspermia[1].

[1] https://en.wikipedia.org/wiki/Panspermia

> ”That distinction belongs to the DNA and microbes contained in the almost 100 bags of feces and urine left behind by American astronauts during the Apollo lunar landings from 1969-1972.”

Gross! Talk about littering and polluting a pristine environment. This is at least as bad as the climbers who leave poop on Everest, where it doesn’t biodegrade.

Is it really so hard to bring poop back with you? Were payload restrictions that tight on the return Apollo journeys?

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

Difficult to figure out how regular the astronauts would be.

they probably had them on a strict diet and knew pretty well.

TIL if someday we travel to new worlds, outside Sol, and find remnants of sentient life having been there, it will most likely be the poop they left behind.

Probably in the sense that they predicted a range of masses that the lander would have to be able to launch with. I doubt they shaved things close enough where a few dozen pounds were make or break though.

The reduction in mass by consumption of food was likely offset by the collection of samples of rock and dust.

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...

They brought it with them (in the form of food and water and what was already in their body), taking it back should have been in their calculations.

I think it’s more likely that it was in their calculations to not bring them back.

They also took a bunch of rocks with them, which had to be accounted for. I have no idea what their exact calculations were like.

It's not a matter of whether or not it was in the calculations. It's how much fuel you could save by leaving some mass on the moon.

They traded food (in the form of poop) for rock samples, if that makes you feel any better.

Not sure why I'm getting down voted like this. The golden rule of exploration is "Take nothing but pictures. Leave nothing but footprints. Kill nothing but time."

By bending these "rules", we have now contaminated a once pristine environment, and new scientific discoveries will have to eliminate our contamination on anything they find. From bacteria to tardigrades, to liquids and other potential chemical contaminant.

> The golden rule of exploration is "Take nothing but pictures. Leave nothing but footprints. Kill nothing but time."

... really? This feels like nothing but unrealistic idealism to me. Wherever we've gone exploring as a species throughout our history, we've left our mark (usually bad). You might dream of a reality where we change nothing at all, but it's just not how things work out in reality. And honestly, leaving a bunch of waste, which is most probably entirely sterilized and cleaner than your kitchen by now, on an uninhabited astral body with no ecosystem or atmosphere, seems a bit less egregious than wiping out local wildlife or cultures.

So we should not strive for it? They left at most 5 kilos of waste on the surface of the moon for an extra rock?

Those were turdigrades, different class.

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

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.

Even if they built a larger rocket it would be better to pack more people, experiments or bring back more samples than poop.

We got enough poop on earth, the bacteria would die due to UV and hard vacuum you could even decontaminate the left overs before chugging them out of the window on your way back home if you want to be extra careful.

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?

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.

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