Once I isolated a few Taumoeba from the Adrian air sample, Rocky built a breeder tank and we let them get to work. It’s just a xenonite box full of Adrian air and a few hundred grams of Astrophage.

As far as we can tell, Taumoeba is very resilient to temperature variations. Good thing, too, because I let it sit at room temperature that one day.

Drugs are bad.

In retrospect, it makes sense that they’d be robust on temperature. They live in a negative-51-degree-Celsius environment, and eat Astrophage, which is always 96.415 degrees Celsius. Hey, everyone likes a hot meal, right?

And boy, do they breed! Well, I gave them a mother lode of Astrophage to work with. It’s the same as throwing yeast into a bottle of sugar water. But instead of making booze, we’re making more Taumoebas. Now that we have enough to experiment with, I get to work.

If you take a goat and put it on Mars, what happens? It dies immediately (and horribly). Goats didn’t evolve to live on Mars. Okay, so what happens if you put a Taumoeba on a planet other than Adrian?

That’s what I want to find out.

Rocky watches from his tunnel above the main worktable as I simulate a fresh new atmosphere in my vacuum chamber.

“No have oxygen, question?” he asked.

“No oxygen.”

“Oxygen dangerous.” He’s been a little edgy since his internal organs caught fire.

“I breathe oxygen. It’s okay.”

“Can explode.”

I pull my goggles off and look up at him. “There’s no oxygen in this experiment. Calm down.”

“Yes. Calm.”

I get back to work. I turn a valve to let a small bit of gas into the vacuum chamber. I check the pressure gauge to make sure that—

“Again confirm: No oxygen, question?”

I jerk my head up to glare at him. “It’s just carbon dioxide and nitrogen! Only carbon dioxide and nitrogen! Nothing more! Don’t ask me again!”

“Yes. No ask again. Sorry.”

Can’t blame him, I guess. Being on fire sucks.

We have two planets to deal with here. No, not Earth and Erid. Those are just the planets we live on. The planets we care about right now are Venus and Threeworld. That’s where Astrophage is breeding out of control.

Venus, of course, is the second planet in my solar system. It’s about Earth’s size with a thick carbon-dioxide atmosphere.

Threeworld is the third planet in Rocky’s home system. At least, Threeworld is what I call it. The Eridians don’t have a name for it, even in their own language. Just a designation: “Planet Three.” They didn’t have ancient people looking up at astronomical bodies and naming them after gods. They only discovered other planets in their system a few hundred years ago. But I don’t want to say “Planet Three” all the time, so I’ve named it Threeworld.

The hardest part about working with aliens and saving humanity from extinction is constantly having to come up with names for stuff.

Threeworld is a tiny little planet—only about the size of Earth’s moon. But unlike our airless neighbor, Threeworld somehow has an atmosphere. How? I have no idea. The surface gravity is only 0.2 g’s, which shouldn’t be enough. Yet somehow, Threeworld manages to hang on to a thin atmosphere. According to Rocky, it’s 84 percent carbon dioxide, 8 percent nitrogen, 4 percent sulfur dioxide, and a bunch of trace gases. All with a surface pressure less than 1 percent of Earth’s.

I check the readouts and nod approvingly. I do a visual inspection of the experiment inside. I’m pretty proud of myself for this idea.

A thin coat of Astrophage sits on a glass plate. I coated the plate by shining IR light through the glass and attracting Astrophage from the other side. It’s the same way the spin drive does it. The result is a uniform layer of Astrophage that’s just one cell thick.

Then I seeded the slide with Taumoeba. As they eat the Astrophage, the currently opaque slide will become more and more transparent. It’s a hell of a lot easier to measure light level than a quantity of microscopic organisms.

“Okay…the chamber has Venus’s upper atmosphere duplicated. As good as I can, anyway.”

I figure the breeding zone of Astrophage is based mainly on the air pressure. Basically, they have to aero-brake from near light speed when they hit the planet. But being so small that doesn’t take very long and of course they gobble up all the heat that’s created.

The end result is that Astrophage come to rest when the air is 0.02 atmospheres thick. So, going forward, that’ll be our standard for pressure. Venus’s atmosphere is 0.02 atmospheres at around the 70 kilometer mark, and the temperature there is about minus 100 degrees Celsius (thanks, infinite supply of reference material!). So that’s the temperature I have the Venus analog experiment set to. Rocky’s temperature-control system works perfectly, of course, even down to ultra-low temperatures.

“Good. Now Threeworld.”

“What temperature is Threeworld’s air at the 0.02 atmosphere altitude?”

“Minus eighty-two degrees of Celsius.”

“Okay, thanks,” I say. I move to the next chamber. It has an identical setup of Astrophage and Taumoeba. I let in the appropriate gases to simulate Threeworld’s atmosphere and temperature at the 0.02-atmosphere pressure area. I get the relevant information from Rocky’s perfect memory. It’s not much different from Venus or Adrian. Mostly carbon dioxide with some other gases running around. No surprise there—Astrophage go for the biggest concentration of CO2 they can see.

It’s a good thing these planets aren’t covered in helium or something. I don’t have any of that aboard. But carbon dioxide? That’s easy. I make that stuff with my body. And nitrogen? Thanks to DuBois and his preferred method of death, there’s a whole bunch aboard.

Threeworld does have some sulfur dioxide, though. Four percent of the total atmosphere. It’s enough that I didn’t want to approximate it away, so I had to make some. The lab has quite a selection of reagents, but no sulfur dioxide gas. However, it does have sulfuric acid in solution. I recovered some copper tubing from a broken cooling coil in the freezer and used it as a catalyst. Worked like a charm to create the sulfur dioxide I needed.

“Okay, Threeworld’s done,” I say. “We’ll wait an hour and check results.”

“We have hope,” says Rocky.

“Yes, we have hope,” I say. “Taumoeba are very sturdy. They can live in a near vacuum, and they seem comfortable in extreme cold. Maybe Venus and Threeworld are habitable for them. They’re good enough for Taumoeba’s prey, so why not for Taumoeba?”