‌It’s been three days since the Great Taumoeba Escape. I’ve taken no chances.‌

I manually shut off all the fuel bays—completely segregating each one from the fuel system. Then, one tank at a time, I opened it, collected an Astrophage sample from the line, and checked it in the microscope for Taumoeba contamination.

Thankfully, all nine tanks passed the test. I brought the spin drives back online and I’m cruising along at 1.5 g’s again.

I cobble together a “Taumoeba alarm” to alert me if this happens again. I should have done that in the first place, but hindsight is 20/20.

It’s a slide of Astrophage—same as I used in the Taumoeba farms—with a light on one side and a light sensor on the other. The whole system is exposed to the open air of the lab. If Taumoeba get ahold of that Astrophage, they’ll eat it, the slide will turn clear, and the light sensor will start beeping. So far, no beeping. The slide remains jet-black.

Now that things have calmed down and the problem is contained, I can start asking the million-dollar question: How did the Taumoeba get loose?

I put my hands on my hips and stare at the quarantine zone. “Which one of you did this?” I say.

None of it makes sense. The farms worked for months without any hint of a leak. The mini-farms are hermetically sealed steel capsules.

Maybe some rogue Taumoeba was lurking on the ship since the last outbreak—back at Adrian. Somehow it didn’t find any Astrophage until just now?

No. From our experiments, Rocky and I learned that Taumoeba can only last about a week without food before it starves to death. And they’re not big on moderation. Either they wildly breed and consume all Astrophage to be found, or they aren’t present at all.

One of these containers must be leaking. I can’t just jettison everything—I need these Taumoeba to save Earth—so what do I do? I have to figure out which one is the problem.

I check each farm as best I can. Since they’re in bins, I can’t operate any of the controls, but I don’t need to. They’re fully automated. It’s a pretty simple system—Rocky tends to find elegant solutions to complex problems. The farm monitors the air temperature inside. If it drops below 96.415 degrees Celsius, it means there’s no more Astrophage because the Taumoeba ate it. So it pumps in a little more Astrophage. Simple as that. And the system keeps track of how often it has to feed them. From that it makes a very rough approximation of the Taumoeba population inside. It adjusts the Astrophage feed rate as needed to control that population and, of course, has a readout to tell us the current state.

I check each farm’s readouts. Each one shows 96.415 degrees Celsius with a population estimate of 10 million Taumoeba. Exactly what they’re supposed to read.

“Hm,” I say.

The air pressure inside those farms is way lower than the nitrogen pressure surrounding them. If any of those farms had a leak, the nitrogen would get in and pretty soon the Taumoeba would all die. But they haven’t. And it’s been three days.

The breeder farms aren’t leaking. It must be the mini-farms. But how the heck does a microbe work its way through half a centimeter of Eridian steel? Rocky knows what he’s doing, and he knows all about Eridian steel. If it wasn’t good for holding microbes in place, he’d know. They don’t have Taumoeba on Erid, but they definitely have other microbes. This isn’t new to them.

All of this leads me to something I would normally consider impossible: Rocky made an engineering mistake.

He never makes mistakes. Not when it comes to creating things. He’s one of the most talented engineers on his entire planet! He couldn’t have messed up.

Could he?

I need definitive proof.

I make more Astrophage test slides. They’re super-handy for Taumoeba detection and easy to make.

I start with the bin containing the two mini-farms—the ones intended for George and Ringo. They certainly seem sealed. They’re just capsule-shaped pieces of metal. All sorts of stuff going on inside, but smooth Eridian steel on the outside.

I peel the duct tape off one corner of the box, pry up the lid, and throw an Astrophage slide in, then reseal everything. Experiment number one: Make sure I didn’t accidentally breed up some Super-Taumoeba that can live in pure nitrogen.

Another fun fact I’ve learned: Once Taumoeba get ahold of an Astrophage slide, it’ll be crystal clear in a couple of hours. So I wait a couple of hours and the slide is still black. Okay, good. No Super-Taumoeba.

I unseal the bin, open the lid, and let it air out for a minute. Then I reseal it. The nitrogen content in there will be nominal now. Way less than Taumoeba-82.5 needs to worry about. If there’s a leak in those mini-farms, the slide will tell the tale.

One hour, no results. Two hours, no results.

I take a sample of the air inside the bin just to be sure. The nitrogen level is nearly zero. So that’s not an issue.

I seal it up again and give it another hour. Nothing.

The mini-farms aren’t leaking. At least, the ones intended for George and Ringo aren’t. Maybe the leak was in one of the mini-farms I’ve already installed.

They’re just glued to the outsides of John and Paul. They’re not protected by the beetle’s hull or anything. I repeat the Taumoeba detection experiment with John and Paul’s bins.

I get the same result: no Taumoeba at all.

“Hm.”

Okay, time for the ultimate test. I remove John, Paul, and the two uninstalled mini-farms from quarantine. I set them on the lab table next to my Taumoeba alarm. I’m pretty sure they’re clean. But if they aren’t, I want to know right away.

I turn my attention to the even less likely culprits: the breeder farms.

If Taumoeba can’t escape Eridian steel, they definitely can’t get through xenonite. One centimeter of that stuff can effortlessly hold in Rocky’s 29 atmospheres of pressure! It’s harder than diamond and also somehow not brittle.

But I need to be thorough. I repeat the Astrophage slide test with all ten of the breeder farm bins. There’s no point in doing them one at a time. I pipeline the whole process. Now all ten of the farms are in sealed bins full of normal air and have an Astrophage slide inside.

It’s been a long day. It’s a good time to take a break and sleep. I’ll leave them overnight to see what happens. I bring bedding up from the dormitory to the lab. If my Taumoeba-detector alarm goes off, I want to be darn sure it wakes me up. I’m too pooped to work up a louder solution. So I’ll just bring my ears closer to the lab table and call it a night.

I drift off to sleep. It feels wrong to sleep without someone watching.

—

I wake up about six hours later. “Coffee.”

But the nanny-arms are downstairs in the dormitory. So of course I get no response.

“Oh, right…” I sit up and stretch.

I get up and shuffle over to the quarantine zone. Let’s see how those Taumoeba farm tests are doing.

I check the first farm’s Astrophage slide. It’s completely clear. So I move on to the next—

Wait. It’s clear? “Uh…”

I’m still not 100 percent awake. I wipe my eyes and take another look. It’s still clear.

Taumoeba got to the slide. It got out of the breeder farm!

I spin to the Taumoeba alarm on the lab table. It’s not beeping, but I run over to get a visual. The Astrophage slide in it is still black.

I take a deep breath and let it out. “Okay…” I say.

I return to the quarantine zone and check the other farms. Every single one of them has a clear slide. The farms are leaking. All of them are leaking. The mini-farms are fine. They’re sitting on the lab table right next to the Taumoeba alarm.

I rub the back of my neck.

I’ve found the problem, but I don’t understand it. Taumoeba are getting out of the farms. But how? If there was a crack in the xenonite, the overpressure of nitrogen would’ve gotten inside and killed everything. All ten farms have happy, healthy Taumoeba populations. So what gives?

I climb down to the dormitory and have breakfast. I stare at the xenonite wall that once housed Rocky’s workshop. The wall is still there, but with a hole cut in it where I’d requested. I’m using the area mainly for storage.

I chew on a breakfast burrito, trying to ignore the fact that I’m one meal closer to coma slurry. I stare at the hole. I imagine I’m a Taumoeba. I’m millions of times larger than a nitrogen atom. But I can get through a hole the nitrogen atom can’t. How? And where did the hole come from?

I’m starting to get a bad feeling. A suspicion, really.

What if Taumoeba can, for lack of a better description, work their way around the molecules of xenonite? What if there’s no hole at all?

We tend to think of solid materials as magical barriers. But at the molecular scale they’re not. They’re strands of molecules or lattices of atoms or both. When you get down to the teeny, tiny realm, solid objects are more like thick jungles than brick walls.

I can work my way through a jungle, no problem. I may have to climb over bushes, weave around trees, and duck under branches, but I can make it.

Imagine a thousand tennis-ball launchers at the edge of that jungle aimed in random directions. How deep into the jungle will the tennis balls get? Most of them won’t get past the first few trees. Some may get lucky bounces and go a little deeper in. Fewer still may get multiple lucky bounces. But pretty soon, even the luckiest tennis ball runs out of energy.

You’d be hard-pressed to find any tennis balls 50 feet into that jungle. Now, let’s say it’s a mile wide. I can make it to the other side, but there’s just no chance a tennis ball can.

That’s the difference between Taumoeba and nitrogen. The nitrogen is just moving in a line and bouncing off stuff like a tennis ball. It’s inert. But Taumoeba is like me. It has stimulus-response capabilities. It senses its environment and takes directed action based on that sensory input. We already know it can find Astrophage and move toward it. It definitely has senses. But nitrogen atoms are ruled by entropy. They won’t “exert effort” to do anything. I can walk uphill. But a tennis ball can only roll so far before it rolls back down.

That all seems really weird. How could Taumoeba, from the planet Adrian, know how to carefully navigate its way through xenonite, a technological invention from the planet Erid? It does not make sense.

Life-forms don’t evolve traits for no reason. Taumoeba lives in the upper atmosphere. Why would it develop the ability to work its way through dense molecular structures? What evolutionary reason could there be to—

I drop my burrito.

I know the answer. I don’t want to admit it to myself. But I know the answer.

—

I go back to the lab and perform a nerve-wracking experiment. The experiment itself isn’t nerve-wracking. I’m just worried that the results will be what I expect.

I still have Rocky’s AstroTorch. It’s the only thing on the ship that can get hot enough to dissociate xenonite. There’s plenty of xenonite to be had throughout the ship, thanks to Rocky’s tunnel system. I cut into the dormitory

divider wall. I can only cut a little bit at a time, then I have to wait for life support to cool things back down. The AstroTorch makes a lot of heat.

In the end, I have four rough circles, each a couple of inches across.

Yes, inches. When I’m stressed out, I revert to imperial units. It’s hard to be an American, okay?

I take them up to the lab and put together an experiment.

I smear some Astrophage on one of the circles and put another circle on top of it. Astrophage sandwich. Delicious, but only if you can get through the xenonite “bread.” I epoxy the two halves together. I make another identical sandwich.

And then I make another two similar sandwiches, but instead of xenonite, I use ordinary plastic discs that I cut from some mill stock.

Okay. Four hermetically sealed Astrophage samples—two with xenonite discs, two with plastic discs, all four of them sealed with epoxy.

I get two clear, sealable containers and set them up on the lab table. I put a xenonite sandwich and a plastic sandwich in each container.

In the sample cabinet, I have a few metal vials full of natural Taumoeba. The original stuff from Adrian, not the Taumoeba-82.5 version. I set the vial in one of the containers, open it up, and quickly seal the experiment. This is a very dangerous road to go down, but at least I know how to contain a Taumoeba outbreak if it happens. As long as I have nitrogen I’m okay.

I go to Breeder Tank One in the quarantine zone. I use a syringe to get the Taumoeba-infected air from the bin, then immediately flood the bin with nitrogen. I tape over the hole made by the syringe.

Back to the lab table, I close up the other container and use the syringe to inject the Taumoeba-82.5 in. Again, I seal that hole with tape.

I rest my chin in my hands and peer into the two boxes. “Okay, you sneaky little punks. Let’s see what you can do…”

It takes a couple of hours, but I finally see results. They’re exactly what I expected and the opposite of what I’d hoped.

I shake my head. “Dang it.”

The xenonite-covered Astrophage in the Taumoeba-82.5 experiment is gone. The plastic-covered Astrophage remains unchanged. Meanwhile in the

other experiment, both Astrophage samples are unharmed.

What that means: The “control” samples (the plastic discs) prove Taumoeba can’t get through epoxy or plastic. But the xenonite samples tell a different story. Taumoeba-82.5 can work its way through xenonite, but natural Taumoeba can’t.

“I’m so stupid!” I smack myself on the head.

I thought I was oh so clever. All that time in the breeder tanks. Generation after generation of Taumoeba. I used evolution to my advantage, right? I made Taumoeba with nitrogen resistance! I’m so awesome! Let me know when I can pick up my Nobel Prize!

Ugh.

Yes, I made a strain of Taumoeba that could survive nitrogen. But evolution doesn’t care what I want. And it doesn’t do just one thing at a time. I bred up a bunch of Taumoeba that evolved to survive…in xenonite breeder tanks.

Sure, it has nitrogen resistance. But evolution has a sneaky way of working on a problem from every angle. So not only did they gain resistance to nitrogen, they figured out how to hide from nitrogen by sneaking into the xenonite itself! Why wouldn’t they?

Xenonite is a complicated chain of proteins and chemicals I have no hope of understanding. But I guess Taumoeba has a way to worm its way in. There’s a nitrogen apocalypse going on in the breeder farm. If you can get into the xenonite walls deep enough that the nitrogen can’t reach, you get to survive!

Taumoeba can’t get through ordinary plastic. It can’t get through epoxy resin. It can’t get through glass. It can’t get through metal. I’m not even sure if it could get through a ziplock bag. But thanks to me, Taumoeba-82.5 can get through xenonite.

I took a life-form I knew nothing about and used technology I didn’t understand to modify it. Of course there were unintended consequences. It was stupidly arrogant of me to assume I could predict everything.

I take a deep breath and let it out.

Okay, this isn’t the end of the world. In fact, it’s the opposite. This Taumoeba can permeate xenonite. No problem. I’ll store it in something else.

It’s still nitrogen-resistant. It doesn’t need xenonite to survive. I tested it thoroughly in my glass lab equipment back when we first isolated the strain. It’ll still do its thing on Venus and Threeworld. Everything’s fine.

I glance back at the breeder farms.

Yeah. Fine. I’ll make a big farm out of metal. It’s not hard. I have a mill and all the raw materials I need. And God knows I have time to spare. I’ll salvage the operational equipment from a farm Rocky made. Only the casing is xenonite. Everything else is metals and stuff. I don’t need to reinvent the wheel. I just need to put it on a different car.

“Yeah,” I reassure myself. “Yeah, this is okay.”

I just need to make a box that can maintain a Venusian atmosphere. All of the hard stuff is already done, thanks to Rocky.

Rocky!

I feel a sudden surge of nausea. I have to sit on the floor and put my head between my legs. Rocky has the same strain of Taumoeba aboard his ship. It’s stored in xenonite farms like mine.

All critical bulkheads of his ship, including the fuel tanks, are made of xenonite. There’s nothing standing between his Taumoeba and his fuel.

“Oh…God