“No,” Prax said. “That’s right. It’s the cascade. It’ll get worse.”
“What’s the cascade?” Naomi asked. Amos slid the pistol into its box and hauled out a longer case. A shotgun maybe. His gaze was on Prax, waiting.
“It’s the basic obstacle of artificial ecosystems. In a normal evolutionary environment, there’s enough diversity to cushion the system when something catastrophic happens. That’s nature. Catastrophic things happen all the time. But nothing we can build has the depth. One thing goes wrong, and there’s only a few compensatory pathways that can step in. They get overstressed. Fall out of balance. When the next one fails, there are even fewer paths, and then they’re more stressed. It’s a simple complex system. That’s the technical name for it. Because it’s simple, it’s prone to cascades, and because it’s complex, you can’t predict what’s going to fail. Or how. It’s computationally impossible.”
Holden leaned against the wall, his arms folded. It was still odd, seeing him in person. He looked the same as he had on the screens, and he also didn’t.
“Ganymede Station,” Holden said, “is the most important food supply and agricultural center outside Earth and Mars. It can’t just collapse. They wouldn’t let it. People come here to have their babies, for God’s sake.”
Prax tilted his head. A day before, he wouldn’t have been able to explain this. For one thing, he wouldn’t have had the blood sugar to fuel thought. For another, he wouldn’t have had anyone to say it to. It was good to be able to think again, even if it was only so he could explain how bad things had become.
“Ganymede’s dead,” Prax said. “The tunnels will probably survive, but the environmental and social structures are already broken. Even if we could somehow get the environmental systems back in place—and really, we can’t without a lot of work—how many people are going to stay here now? How many would be going to jail? Something’s going to fill the niche, but it won’t be what was here before.”
“Because of the cascade,” Holden said.
“Yes,” Prax said. “That’s what I was trying to say before. To Amos. It’s all going to fall apart. The relief effort’s going to make the fall a little more graceful, maybe. But it’s too late. It’s too late, and since Mei’s out there, and we don’t know what’s going to break, I have to go with you.”
“Prax,” Cassandra said. No. Naomi. Maybe his brain wasn’t really up to full power even now.
“Strickland and that woman, even if they think they can keep her safe, they can’t. You see? Even if they’re not hurting her, even if they’re not, everything around them is going to fall apart. What if they run out of air? What if they don’t understand what’s happening?”
“I know this is hard,” Holden said. “But shouting about it won’t help.”
“I’m not shouting. I’m not shouting. I’m just telling you that they took my little girl away, and I need to go and get her. I need to be there when you open that door. Even if she’s not there. Even if she’s dead, I need to be the one who finds her.”
The sound was crisp and professional and oddly beautifuclass="underline" a magazine slipping into a pistol. Prax hadn’t seen Amos take it back out of its box, but the dark metal was in the man’s huge hand. Dwarfed by his fingers. While he watched, Amos chambered a round. Then he took the gun by its barrel, careful to keep it pointing at the wall, and held it out.
“But I thought…” Prax said. “You said I wasn’t…”
Amos stretched his arms out another half inch. The gesture was unmistakable. Take it. Prax took it. It was heavier than it looked.
“Um. Amos?” Holden said. “Did you just give him a loaded gun?”
“Doc needs to go, Cap’n,” Amos said with a shrug. “So I’m thinking he should probably go.”
Prax saw the look that passed between Holden and Naomi.
“We might want to talk about that decision-making process, Amos,” Naomi said, shaping the words carefully.
“You betcha,” Amos said. “Soon as we get back.”
Prax had been walking through the station for weeks as a native, a local. A refugee with nowhere to flee. He’d gotten used to how the hallways looked, how people’s eyes slid over him in case he’d try to lay his burdens on them. Now that Prax was fed and armed and part of a group, the station had become a different place. People’s eyes still slid across them, but the fear was different, and hunger fought against it. Holden and Amos didn’t have the gray of malnutrition or the haunted look around their eyes of seeing everything they thought was immutable collapse. Naomi was back at the ship, hacked into the local security network and ready to coordinate the three of them in case they got split up.
For the first time perhaps in his life, Prax felt like an outsider. He looked at his hometown and saw what Holden would see: a huge hallway with paints and dyes worked into the ice up high on the wall; the lower half, where people might accidentally touch it, covered in thick insulation. Ganymede’s raw ice would strip the flesh from bone with even the briefest contact. The hallway was too dark now, the floodlights beginning to fail. A wide corridor Prax had walked through every day he was at school was a dim chamber filled with the sounds of dripping water as the climate regulation failed. The plants that weren’t dead were dying, and the air was getting the stale taste at the back of his throat that meant the emergency recyclers would be coming on soon. Should be coming on soon. Had better.
Holden was right, though. The thin-faced, desperate people they passed had been food scientists and soil technicians, gas exchange experts and agricultural support staff. If Ganymede Station died, the cascade wouldn’t stop here. Once the last load of food lifted off, the Belt, the Jovian system, and the myriad long-term bases in their own orbits around the sun would have to find a different way to get vitamins and micronutrients for their kids. Prax started wondering whether the bases on the far planets would be able to sustain themselves. If they had full hydroponics rigs and yeast farms and nothing went wrong…
It was a distraction. It was grasping anything other than the fear of what would be waiting behind that door. He embraced it.
“Hold up! All y’all.”
The voice was low and rough and wet, like the man’s vocal cords had been taken out and dragged through mud. He stood in the center of the ice tunnels intersecting before them, military-police body armor two sizes too small straining to keep his bulk in. His accent and build said he was Martian.
Amos and Holden paused, turned, looking everywhere but at the man before them. Prax followed their gazes. Other men lurked, half hidden, around them. The sudden panic tasted like copper.
“I make six,” Holden said.
“What about the guy with the gray pants?” Amos asked.
“Okay, maybe seven. He’s been with us since we left the ship, though. He might be something else.”
“Six is still more than three,” Naomi said in their ears. “You want me to send backup?”
“Hot damn. We’ve got backup?” Amos asked. “Gonna have Supitayaporn come down and talk ’em all to death?”
“We can take them,” Prax said, reaching for the pistol in his pocket. “We can’t let anyone—”
Amos’ wide hand closed over his own, keeping the gun in his pocket and out of sight.
“These aren’t the ones you shoot,” Amos said. “These are the ones you talk to.”
Holden stepped toward the Martian. The ease with which he held himself made the assault rifle on his shoulder seem almost innocuous. Even the expensive body armor he wore didn’t seem at odds with his casual smile.
“Hey,” Holden said. “There a problem, sir?”