Greg Egan - The Clockwork Rocket

“It might seem tempting to try to spin the Peerless around a horizontal axis, in the hope of making the gravity in the fields as close as possible to the old direction—but I’m afraid the mountain’s center of mass is so low that it wouldn’t work out that way. There’s also a question of stability: if you try to spin a cone around anything other than its axis of symmetry, the slightest disturbance can set it wobbling. So we really have no choice: the mountain needs to spin around a vertical axis, running from the summit to the base.”

She glanced down at Frido. Should she have had him stand beside her, backing her up, confirming these technical claims? Everyone understood centrifugal force, but half the crew would still have to take the finer points on faith.

Frido gazed back at her with a neutral expression. They both knew that he’d been preparing to move against her. It was too late to try to bring him on side.

“We’ll need to install two dozen small engines,” Yalda continued, “spread out down the slope of the mountain, along two lines on opposite sides of the axis. These will be very gentle devices compared to the ones we’ve used to accelerate, but we’ll still need to put them in deep pits so their thrust doesn’t merely tear them loose—or peel away parts of the surface of the mountain.

“That means digging into the rock out there, with no gravity to hold us down. It also means working in an air-filled cooling bag, to avoid hyperthermia. No one has ever done anything like this before. And however optimistic we are about it, it’s more work than the usual construction crews could hope to complete in time for us to sow the crops. Everyone who isn’t working in the farms will have to help. Once the construction crews have worked out the protocols, they’ll start training other people to join in. I’ll be among the first of their students, myself—because nothing could be more important than this.”

“Stints of dangerous work in the void, possibly for nothing?” Delfina interjected. She was in the front tier, a few strides left of Frido. “That’s your solution to an agricultural problem?”

“What do you suggest instead?” Yalda asked her.

“Find another food source that isn’t so dependent on gravity,” Delfina replied. “What are the arborines living on, in their forest?”

“Lizards, mostly. Which are living on mites—which in turn feed on bark and petals.”

“We could get used to lizard meat,” Delfina declared. “If it’s good enough for our cousins, why not eat it ourselves?”

“I’m sure we could,” Yalda conceded, “but the whole forest only supports about six arborines.”

“We can’t farm the lizards more intensively?”

“That’s… worth considering,” Yalda said. “But it would be another gamble, and even if we could make it work the payoff would come too late. The only thing we know for sure is that we can raise a wheat crop under gravity. Once we spin the Peerless , all we’ll have to do is prepare new fields and plant the seeds.”

“Where, exactly?” Delfina pressed her. “Which chambers were built with their floors pointing away from the mountain’s axis?”

“We’ll have to improvise for the first crop,” Yalda admitted. “We’ll have to lay down fields on surfaces that used to be walls—we won’t have time to carve out new chambers with the ideal geometry.”

“And what happens if we need to fire the engines? To avoid some unanticipated obstacle?” Delfina was enjoying this; someone had prepared her well.

Yalda did her best not to grow flustered. “As things stand, we’d need to get rid of the spin first. But there’s no reason in principle why we couldn’t redesign the attitude controls and the engine feeds to work while the Peerless was rotating.”

Delfina hesitated, as if she’d finally reached the end of a list of objections that she’d committed to memory. But her contribution wasn’t over.

“I’m sorry,” she said, “but I’m not convinced. On balance, I don’t think your plan is worth the risk. I won’t be joining any work team for this purpose.”

Yalda said, “There is no coercion here. You’re free to make your own decision on this.”

“And free to persuade my friends to make the same decision, I hope,” Delfina added cheerfully.

“Of course.” Yalda was angry now, but she was not going to change her stance and start making threats. Help spin the mountain, or you can go without food next harvest.

Far better, she decided, to call the spoilers’ bluff.

“But we’ll need to start drawing up the rosters,” she said, “so I’d like to get the numbers clear right now. How many people are prepared to work to make this happen—either in the farms, or out on the slopes? Please raise a hand if you’re willing to do that.”

About a third of the crew responded immediately. For a long, painful moment it looked to Yalda as if that burst of enthusiastic support was all she would get, but then the numbers began to grow.

In the end, only about two dozen people chose to side with Delfina. Most were from the feed chambers, sending her a message about Nino. No doubt there were many more who wanted the saboteur dead, but they weren’t going to risk the crops—or even risk being seen as risking the crops—just to express their anger over something else entirely.

Frido was not among the dissenters. At some point he had counted the numbers around him and decided to raise his hand.

17

As they waited to use the airlock, Yalda helped Fatima into her helmet and cooling bag. No one’s flesh was flexible enough to conform to the shape of the fabric perfectly—and the whole point was to ensure that there was air moving freely over your skin—but if you let the bag hang too loosely anywhere it just blew out into a rigid tent, leaving you fighting it with every move. The trick was to come close to filling the bag but to wrinkle your skin as much as possible, creating a series of small air channels between skin and fabric.

Yalda finished checking the fit. “I think you’re right now,” she said.

“Thanks.” Fatima reached into the hold beside them and took out two canisters of compressed air, passing one to Yalda. Yalda attached it to the inlet at the side of her own bag.

“Someone should find a better way to keep cool,” Fatima suggested.

“In time for the next shift?” Yalda joked.

Ausilio had finished pumping down the airlock pressure; he slid the external door open, took hold of the guide rail just outside the exit, then pulled himself through. As soon as he’d reached back to slam the door closed, Fatima opened the equaliser and air hissed slowly back into the lock.

Yalda was growing tired of these laborious preparations, shift after shift, but she kept her frustration to herself. Three more stints, and she’d never have to go through this rigamarole again.

Fatima entered the airlock and began working the pump energetically, bracing herself with three hands against the clearstone walls.

By the time Yalda was through onto the slope, Fatima and the rest of the team were already out of sight. Yalda swung herself between the guide rails and set off down the mountain, moving briskly but always keeping at least two hands on the rails. In the absence of gravity she ought to have been oblivious to the gradient of the slope, but the rim of the inverted bowl of garish color trails above her matched the old horizon perfectly, making it impossible to think of the ground as level.

The new horizon was a dazzling, multicolored circle where the fastest ultraviolet light from the old stars was shifted to visible frequencies before giving way abruptly to blackness. Straight ahead of her—“downhill”—the more modest trails of the orthogonal cluster shone sedately. Away from the guide rails, silhouetted in the starlight, dead trees sprawled at odd angles. Notwithstanding the high altitudes to which they’d been accustomed, their roots had not been enough to keep them cool in the complete absence of air. Patches of red moss had colonized the deadwood, but its faint light suggested that it was struggling.