White Crystal Butterflies | Wattys 2021 Shortlist | ✔

Chapter Thirty

Liu is so nervous, she keeps fumbling over simple knots, so I'm the one who sets up most of our rappelling gear. The ice in the tunnel is thick and hard. I don't foresee any problems anchoring ourselves directly to it, but I worry what it'll be like further down. These tunnels clearly don't stay cold all the way to the bottom, and we have no idea how far we'll have to descend. The Isoptera's signal is about the weakest I've ever seen still making it to a receiver. If the probe had been any lower-quality, I'm sure its transmitter pod would not have managed this range at all: we're so far away, the estimated distance between us and Krüger reads as nothing but an error.

Liu has barely said a word since we first found the signal. I do see her checking readings on her goggles, though, and at one point she pulls out a tiny pocket notebook to jot something down. I suspect we've discovered where Mahaha's methane pockets and the missing water in its system both come from. The tunnel, as I work at the rim of it, continues to spit up a constant stream of snow. The crystals are tiny, freshly formed. When open to the sky, this thing must serve as a chimney, spitting vapor back into the clouds.

I wonder how many of these there are on Mahaha.

Finally, I rope myself into climbing gear, pull my backpack on for extra weight, and swing myself over the tunnel rim to test our first anchor in the ice. My crampons bite the tunnel's smooth sides, flaking off thin layers like chips of mica. This ice must all be deposition from the moisture blowing up from below, pulled from the air and built up millimeter by millimeter over decades, if not millennia. It almost feels like a shame to send an ice screw into such a pristine formation, knowing the scar will stay there for half of forever.

The ropes hold. I descend carefully to the first tunnel split, noting everything around me in the claustrophobic space. I hope these passages don't get narrower as we go along. The receiver now clipped to my jacket—and strung on a cord around my neck for good measure—beeps softly, sometimes intermittent, but by-and-large consistent so long as I don't block its line of transmission. At the tunnel split, I hold it out over one of the two branches. It goes silent. I move it to the other branch, and the beeping returns.

"It works!" I call up the tunnel. There's a sound of relief from Liu above. "I'll take the rope down the right path, and call you when you can start coming down. Are you okay to start rappelling on your own?"

"I think so..." Her voice wavers.

"Don't worry," I say. "I'll walk you through it."

Like I so long ago promised to do when I offered her a place on this team. That guilt weighs me down until I close my eyes, acknowledge it, too, and stow it away. I'm not the legend she believed I was when that invitation was extended. I've fucked up, broken promises, and gone back on my word. I've denied her—and Krüger—the guided freedom this mission was supposed to entail, and while I started to give back the training element in the same sessions that taught Liu rappelling, I've got a whole lot more to make up for.

That's going to take another apology.

But for now, we need to focus.

"Stay in touch over your headset," I say. "We'll test how far apart we can be before they stop communicating."

I hop off the wall and glide down the rope into the tunnel with the signal, feeding out more rope as I go. It's another six or seven meters before I find the next split. I'm deep enough now that the already poor sunlight from above has been reduced to a glimmer off the tunnel walls. I switch my headlamp on and dial it down to the lowest setting. Its beam flashes up and down the ice. The tunnel walls are transparent for a good twenty centimeters in, their internal layers refracting the light and sending rainbows scooting through them. It's like the whole place is made of diamond.