October 2021

No one really expected those little…what are they called? Ah yes, water bears. Moss piglets. Tardigrades, those micro-animals found almost everywhere on Earth and virtually indestructible. Anyway, no one really expected them to survive the crash. And yet they did. All shriveled up like tiny pieces of dust just waiting for the right moment to re-emerge. And then no one really expected to find water on the Moon. Yet in 2008 large amounts were found at the poles and embedded in lunar soil. No one really thought there was any way those little creatures would ever come into contact with Moon water, and yet they did. Now here I am sitting across from my granddaughter, my Little One, trying to explain how we came to have so many of them here on the Moon.

“How did it happen, Grandpa?”

Well, Little One, let’s start at the beginning. You see, in 2019 when the Israeli lunar lander, Beresheet, crashed on the Moon it contained thousands of dehydrated water pigs (I know that’s not really their name, but it’s what many of us call them now) that spread over a wide area on the Moon’s surface. No one really thought those little water pigs scattered on the Moon’s surface could be a problem. I mean, how could they possibly survive all those years dried up like that? And yet they did.

Then when all those wealthy men came to mine the Moon, that’s when it happened. The mining groups started digging and the dust spread everywhere.  And Little One, I’m sure you guessed it, those dried up little tardigrades not much bigger than dust, spread too.

“But Grandpa, how did we get so many of them?”

Ah, Little One, that’s where the oil comes in. You see, the miners needed some way to lubricate the drills. As a result, they designed special oil made from algae to be used on the Moon. You may remember reading in history class how once we figured out how to make biofuels from algae people started using biofuels for all sorts of things. Turns out they made lubricants with the algae too. And guess what? Algae is one of those little water piglets’ favorite foods!

And when the men started drilling, not only did the dust and water bears spread, droplets of that algae lubricant spread too. And whenever a water bear landed in algae those newly hydrated water bears had something besides each other to eat. 

“Wait. Grandpa, you mean the water bears ate each other?”

Yes, Little One. When the early miners came and started digging around to see what was underground some of those little water piglets, I mean water bears, got blown into the holes and the lucky ones made it to the water. Well, at that time all they had to eat was each other, and I guess that would have been the end of them if the miners hadn’t come back with drills and algae-based lubricants. Oh, and bacteria. Let’s not forget the bacteria that hitched a ride in the lubricant. That was another food source for our soon-to-be popular little piglets.

“Grandpa, what about oxygen? How did they breathe? The Moon didn’t have oxygen back then.”

That’s where the exploratory crews came in. They figured out how to get air from the large water stores at the Moon’s poles and pumped that air down those tunnels. That way they could walk around in the tunnels and see what they had found. For the water bears it was a recipe for life!

And you know how the tunnels are all connected today, right? Well, before anyone really figured out what was happening, the more habitable the miners made the tunnels for themselves, the more habitable the tunnels became for the little water bears. Before long people started bringing down little potted plants and watering ‘em. The water bears just loved that!

And boy did those little guys take off! Once the water piglets, I mean water bears, had a constant supply of food, they started colonizing just about every moist nook and cranny they could find. And anyone who had plants? Well, what they really had was a water bear Garden of Eden.

At first no one noticed. I mean, how could they? The little guys are microscopic. No one really thought much of taking parts of plants to different tunnels. And by the time anyone really noticed, those water bears had spread throughout all of the tunnels. And instead of getting rid of the little buggers, people turned them into pets. Pretty soon everyone had a little terrarium with a magnifying lens on top. People just loved watching the little water bears as they romped around their mini-gardens.

“My teacher gave each of us our own terrarium so we could conduct experiments on them. We have to find experiments that don’t hurt them. But I can’t figure out what hurts a water bear and what doesn’t. I mean, if I take mine out they just dry up and wait for water to come again. That’s really boring.”

And that, Little One is our problem. At first people thought having these little terrariums helped with people’s depression from living in the tunnels. Heck they even started naming the tunnels after the little piglets.

“Yes, I know this one. I live in tunnel TT1 and you live in TT2 and my best friend lives in TT3. And my school is in MPT1.”

True enough. And I think most people, myself included, forget what the letters stand for. Do you remember?

“Yes! We had a test on this just last week. TT stands for Tardigrade Tunnel. And MPT stands for Moss Piglet Tunnel. And of course, the numbers help you keep track of what level you’re on. Everyone knows that!”

Good girl! You’re so smart! Now do you know why some of us call the little creatures water pigs instead of water bears or moss piglets?

“No, Grandpa. I don’t know. I just know that a lot of the older people don’t like the little water bears very much.”

Well then, let me continue the story and you’ll learn. You see, as more and more people started raising water bears in their little terrariums, people wanted more life down in the tunnels. One day an enterprising young woman brought lots of larger plants down to the tunnels and sold them. Everyone just had to have at least one in their compartment. By now you’ve studied botany, and you know along with oxygen plants give off water, and in an enclosed space the atmosphere can become moist.

Put that together with people’s waning interest in the water bears… and what do you have? A recipe for disaster. You see people started abandoning their little terrariums and before anyone figured it out, the little piglets had escaped and were taking up shop all over the place – anyplace that had moisture and some food, they’d colonize it. Pretty soon it got to be that they’d eat just about anything organic — algae, plants and bacteria of course, and then they started nibbling on people. Who would have thought? And yet they did.

It seems that somehow when people handled their plants the water bears hitched a ride. And without any plant material to eat, the water bears began to forage on all the little beasties that live on us. It really wasn’t until someone got sick that we gave any thought to the notion that they might be inside us too. Now they’re everywhere. We can’t escape them.

“In school we get to go on hunts to see who can find the most tardigrade outposts. I found one in every corner of our kitchen tube! But Marty found more than me. He even found an entire colony living on his toothbrush! Yuck! He took it to school to show everyone. Now his mom makes sure he puts the toothbrush in the desiccator every day. He had to go to the doctor to see if any were living in his mouth. The doctor had to clear out his mouth with that special stuff. Marty said it tasted horrible!”

Ah, poor Marty. I guess from now on he’ll be more careful about protecting his belongings.

“Yeah, the doctor gave him a stern lecture on keeping all moist items like toothbrushes, wash clothes and even sweaty shoes inside desiccators. When I told Mom about Marty she gave me the same lecture! I’m not lazy like Marty. I always put everything in the desiccators. I don’t want to drink that awful medicine. Yuck!”

And now Little One it looks like it’s just about your bedtime. Our story has come to an end. You now know how we got so many water piglets, um, I mean water bears, in the tunnels.

“Grandpa, do you think we’ll ever get rid of them all? Do you think we’ll always have to sleep in dry chambers to keep out the water bears when we sleep?”

I don’t know Little One. Maybe. Now let’s get you tucked in and your chamber closed up. There you go, sleep tight and don’t let the water bears bite.

“Grandpa?”

Yes, Little One?

“I heard that we can never go to Earth. Is that true?”

I don’t know, Little One. Maybe one day. Now go to sleep and have wonderful dreams.

As I walk away I can’t help but think that I’ve lied to her for the first time. How can I tell her scientists have found that the water bears have evolved to the point of becoming a new species? How can I tell her of the fear that if we’re allowed back on Earth this species will spread and infect everyone as they have us? In the past people feared how living at one sixth of Earth’s gravity would affect people’s survival when they returned to Earth. Now it’s the fear of bringing back Moon water bears that haunts us. Who would have thought something as simple as sending tardigrade dust into space would prevent us from returning to Earth? And yet it has.