Tardigrades May Still Be Living on the Moon After Lunar Lander Crash

The only known creature that might live on the moon certainly looks freakish. With four pairs of clawed legs and a general appearance of an overstuffed air mattress complete with a mouth that looks like a vacuum attachment part, it certainly appears alien — if you could see it with the naked eye, that is.

But most tardigrades are microscopic Earthlings, in fact. They only got to the moon due to an unfortunate crash of an Israeli spacecraft in 2019 that included some of the creatures as part of a kind of time capsule.

Since then, scientists and web denizens alike have questioned the possibility of whether these hardy microscopic animals that can survive extreme temperatures, radiation, and other pressures might have survived the crash and the harsh conditions of the moon.

“It’s almost certain that nothing survived,” says Jasmine Nirody, an organismal biologist at the University of Chicago who studies tardigrades.

But if the capsule that contained them survived intact, it’s possible the creatures are surviving in a suspended state.

What are Tardigrades?

Tardigrades, also known as water bears, aren’t just one species, but a phylum that contains many hundreds of species, each specialized to different ecological niches found across the planet — some of them very extreme.

These tiny animals are usually microscopic, with the largest species only reaching about the size of a single period on a printed page in ordinary font. In terms of taxonomy, they are the closest living relatives of arthropods — the phylum that includes spiders and insects.

They are famous among scientists for their ability to survive things that most other life couldn’t. They can withstand an extreme lack of water, oxygen, and extreme pressures and temperatures. They can also deal pretty well with starvation and radiation — the kinds of obstacles they might face on the moon.

Read More: Tardigrades, or Water Bears, May Help Unlock Slowing the Aging Process in Humans

How Did Tardigrades Get to the Moon?

The whole reason people are even debating whether there is life on the moon, or at least debating seriously, comes down to a failed Israeli space mission to leave a digital time capsule. Israel’s Beresheet was an unmanned spacecraft that included 1,000 tardigrades stored in a time capsule, which also contained digital records of books, Wikipedia, and other items. The tardigrades were added almost as an afterthought, since previous research had shown the creatures can survive the vacuum of space for a time.

However, the spacecraft crashed on April 11, 2019, due to a failure of its equipment. It’s unclear whether the time capsule and the tardigrades inside survived the impact and crash. Nirody doubts they did, though she admits that “I’ve never crashed tardigrades onto anything, so I don’t know.”

How Could Tardigrades Survive the Moon?

To survive most of the extreme conditions that tardigrades encounter, they typically enter a hibernation-like state of dehydration. This usually takes them several minutes to do, Nirody says, so if the tardigrades weren’t in this state upon crashing, they would have been more vulnerable to the force of the impact. But once in this state, tardigrades can survive for decades — we don’t really know how long because nobody has tested them for longer, Nirody says.

Since they apparently were in a dehydrated state when placed in the capsule, that would mean they were hardier. But they still have extreme conditions to contend with. Temperatures without an atmosphere there swing from nighttime lows of -208 degrees Fahrenheit to daytime highs of 250 degrees Fahrenheit. Tests have shown that tardigrades can survive these temperatures, as long as they remain in their dehydrated state. They could also likely contend with some of the radiation they would experience without Earth’s protective atmosphere.

Could Tardigrades Live on the Moon?

Still, remaining suspended in a dehydrated state isn’t exactly life, per se. In order to reproduce, tardigrades would need to exit that state — something they don’t typically do unless they encounter water, which doesn’t exist on any sort of level on the moon high enough for the creatures. 

“They don’t come back to life unless they are rehydrated,” Nirody says. 

Once rehydrated, they would also need food, which for water bears is plant cells, algae, or small invertebrates, not moon dust. In other words, it’s not so much that they could live on the moon, but that they wouldn’t die.

If astronauts returned to the crash site and recovered the time capsule, surviving tardigrades intact, it’s possible that they might come out of their suspended state, but that would likely entail removing them from the moon again. 

“We could drop them off on the moon for a sleepover and pick them up later, and they’d be OK,” Nirody says. Otherwise, “if they come back [from rehydration] and the conditions are bad, they’d just die.”

But until someone checks more closely, say on a lunar mission to the crash site, it’s unlikely that we’ll know for sure. Until then, there is a faint hope that tardigrades survive — though likely not living it up — on the moon.

Read More: Tardigrade Tattoos Could Pave the Way for Microscopic Medical Devices

Article Sources

Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• NASA. Weather on the Moon

Joshua Rapp Learn is an award-winning D.C.-based science writer. An expat Albertan, he contributes to a number of science publications like National Geographic, The New York Times, The Guardian, New Scientist, Hakai, and others.

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