21 RACING THE CLOCK

21 RACING THE CLOCK Lunar day 217 Late afternoon Two minutes later, I was back on the surface of the moon. Chang had gathered the emergency equipment and rushed me through suiting up. Now we were heading clockwise around the base as quickly as we could go. I was terrified. I feared I was going to get plugged by a falling piece of space junk, or that the patch on my space suit might fail, or that a thousand other things might go wrong. Chang wasn't exactly being reassuring. He was so concerned about saving Nina, he wasn't very

focused on me. He kept charging ahead, almost seeming to forget about me, then getting annoyed that I was slowing him down. "Come on," he chided as we passed the rover garage. "Nina doesn't have much time." "I'm doing my best," I told him. "Well, we need to move faster," he said sternly. "Try to keep up." I picked up the pace, but it was a struggle. The exertion made me use a lot more oxygen than I wanted to, which made me worried—which made me breathe even heavier, which used even more oxygen, and so on. My heart was pounding in my chest like I was running a marathon. We rounded the science pod to the north side of the base. I had never been there before, and since there were no windows facing this direction, I'd never been able to see it. Moon Base Alpha wasn't very attractive, but this area made the rest of it look like the Garden of Eden. It was full of ugly gray machinery: the water reclamation unit, the power storage for the solar arrays, the devices that made oxygen and filtered our air, and a whole bunch of other unattractive, clanking things that did stuff I didn't understand but that probably kept all of us

alive. Plus, every piece of broken machinery and unused scrap of building material had been dumped there. With no atmosphere to erode it and no wind to blow it away, it all just sat there, and would still be sitting there in ten thousand years. It was as though humans had scoured the earth for the least attractive industrial park and then rebuilt it on the moon. A thick ridge of dark, ancient volcanic stone poked through the moon dust ahead. It ran from the solar array to underneath the moon base. "That looks like our lava tube," Chang told me. "It's buried," I said. "How do we get into it? How'd Nina get into it?" "There, I'll bet." Chang pointed to a gap in all the machinery along the wall of the base, where a large sheet of steel lay on the ground. If we hadn't been specifically hunting for it, we might have easily overlooked it; it blended in with all the other garbage. On earth, the steel might have weighed several hundred pounds. Here, Chang lifted one end with ease. Below it was the entrance to the lava tube. "Looks like we found the right place," Chang said. He propped the steel sheet against the water

reclamation unit. I stared at the gap in the rock warily. It was much smaller than the entrance to the operations pod at MBB. Even though I was afraid to be out on the lunar surface, the tunnel didn't look much more inviting. It was merely a narrow, dark, jagged hole, the kind of place you could imagine dangerous things lurking inside of. I knew there weren't any such things as space snakes, but if there were, they would have lived in holes like this. "Let's go," Chang ordered. "I'll lead the way." We each had spotlights built into our helmets for getting around on the lunar surface during the long periods when the sun wasn't out. Chang flipped his on and stared into the hole. The light made it less daunting, but it was still awfully spooky. Chang descended into the tube. He was a big guy and his suit made him even bigger, so the narrow entrance was a tight fit. He had to duck his head to get under the moon base. "All right," he told me. "Come on down." I flipped on my own helmet lights and edged into the hole after him. Since I was much smaller, it was easier for me to get inside, although I still took care around the jagged rocks.

We had left the sheet of steel that had concealed the hole propped against the water reclamation unit above, although there hadn't been much room between the unit and the lava tube to do this properly. I hadn't gotten far into the tube before the steel succumbed to gravity and toppled. It crashed back to the surface right above my head, making the tube even darker. I figured the same thing must have happened when Nina had come into the tube the night before. And with the steel over it, the entrance was hidden perfectly. It made sense that the search parties that had come through earlier hadn't looked for Nina underneath a flat piece of steel on the ground. After all, Nina was a human being, not an ant. And no one had known there was a lava tube underneath the moon base. Except Nina, apparently. The tube descended steeply beneath the foundation of the moon base, which was three feet of solid concrete. Just below it, we came across the operations pod. It looked almost exactly the same as the one at MBB. It was smaller and the air lock was an older model, but the basic design was the same. Chang

already had the air-lock door open. "Hurry," he told me. I stepped inside after him. He closed the door behind us, then pressed the button to activate the repressurization. It didn't work the way it was supposed to. The entire air lock shuddered like a balky washing machine, and then a red warning light flashed on the ceiling. I knew that at least some atmosphere had been created, because I could suddenly hear things outside my helmet, but something definitely seemed to be wrong. There was a loud, sputtering noise, like a generator struggling to provide energy. "Warning," a pleasant computerized voice said, although it was barely a whisper, as though it was running out of power. "Pressurization has been completed, but due to a malfunction in the oxygenation system, oxygen levels are critically low. Please exercise caution and do not mphrfllthhppp." The warning decayed into gibberish as the central computer died. The red warning lights flickered around us. That wasn't exactly reassuring. I had to fight to keep from hyperventilating and gulping all my oxygen down at once.