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…”