“Has anyone alerted the Venusian defense system?” Wahram asked.

“Yes, Wang’s qube did that, and now Wang too, but the sunshield’s AI did not find that the data transmitted represented a hazard. We suspect something is wrong with it.”

“Did the sunshield AI explain itself?” Wahram asked. “I need to see that whole exchange, please. Display as text,” and then he was reading the table screen so intently that it seemed his exophthalmic eyes might pop out of his head entirely. Swan let him read and conducted her own quick conversation with Pauline.

“Pauline, say we can’t convince the sunshield’s AI to act, is there anything we could do from here?”

Pauline took a few seconds, then said, “A countermass arriving at the pebbles’ meeting point at the rendezvous moment and hitting the mass at a tangent would push the paired mass off to the side, thus missing the sunshield. After the impact, the sunshield’s security system would presumably react to any detritus flying its way. The countermass should have approximately an equivalent momentum to the pebble mob, to vector the paired mass away successfully.”

“How big is the pebble mob?”

“It looks like it will mass about the equivalent of ten ships of this size.”

“This ship? So… if this ship was moving ten times faster than the pebbles?”

“That would make a momentum equivalency, yes.”

“Can this ship get there in time, and going fast enough?”

By now Wahram was listening to them rather than reading.

“Yes,” Pauline said. “But only by accelerating at this ship’s maximum acceleration, and starting as soon as you can.”

Swan looked at Wahram. “We have to tell the ship’s crew about this. And everyone else too.”

“True,” he said, taking up his napkin and patting his mouth. He surged to his feet. “Let’s go up to the bridge.”

By the time they got there, the officers of the ship were already gathered before their AI’s biggest screen and were looking into a graphic of the pebble array very similar to the one Wahram and Swan had been looking at.

“Oh good,” Wahram said when he saw it. He was huffing a bit from the run down hallways and up stairs. “You see the problem we have.”

The ship’s captain glanced at him and said, “I’m glad you’re here. Indeed a big problem!”

Wahram said, “Swan’s qube says our ship here can serve to ward off the attack, by colliding with the pebbles at their rendezvous point.”

The captain and everyone on the crew looked startled at this idea, but Wahram gave them little time to adjust: “If we decide to do this, are there enough lifeboats for everyone aboard?”

“ ‘Lifeboat’ is not the right word,” the captain said, “but yes. There are lots of small ferries and hoppers on board, and most of the passengers could be put in them. Also there are more than enough personal spacesuits to send everyone out on their own. There are supplies in the suits to last ten days, so in that sense they’re better than the ferries, which don’t carry that kind of emergency supply. Everyone would get picked up, either way. But…” The captain looked around at the ship’s officers. “I should think the Venusian defense system would take this kind of thing on. Are we sure they won’t? And”—gesturing at the screen—“is this image evidence enough for us to change course, accelerate, and abandon ship?”

Wahram said, “We have to trust our AIs here, I think. They’re issuing their warning because we programmed them to react to input like this.”

“But they set up this fine-grained detection system on their own, I’m being told.”

“Yes, but I guess you could say we asked for that too. Wang asked for better protection. So—we’ve already made the decision to trust them.”

The captain frowned. “I suppose you’re right. But I don’t like it that the sunshield security doesn’t recognize this as a problem. If it did we wouldn’t have to throw our ship into harm’s way.”

“That may be balkanization rearing its head again,” Inspector Genette said from the doorway. “The Venus sunshield isn’t connected to the warning system that saw these pebbles, and it’s heavily firewalled from influences just like Wang’s qube. So it may not be equipped to believe the input.”

“What do the Venusians say?” the captain asked.

“Let’s ask them and find out,” suggested Wahram.

Swan said, “We have to tell them immediately, of course, but the Venusian leadership is notoriously opaque. How soon will they reply? And what do we do in the meantime?”

The captain was still frowning. He glared at Swan, as if because she had brought up the problem, it was her fault. “Let’s prepare to abandon ship,” he said unhappily. “We can stop at any point if it seems right. But if we confirm that we need to do this, we don’t have much time.” He stared at the screen and said, “We need to accelerate hard to make that rendezvous. Tell everyone to prepare for another flip. Mobile, what speed will it take in terms of g-force on the passengers to get to this convergence point in time?”

The AI spoke a string of numbers and coordinates, which the captain listened to closely. The captain then said, “We have to flip right now, then accelerate at a three-g equivalent for the next three hours, while angling slightly out of the plane, to a spot above the edge of the sunshield.”

This was bad news; suiting up in three g was hard, rarely attempted except in emergency drills.

“Tell everyone on board rated for spacesuits to please get started getting into them,” the captain ordered, then scowled. “Everyone else into the ferries. We need to accelerate immediately on making the flip.” Then, after looking around at his people on the bridge, he went to the intercom and began to explain the situation to the passengers himself.

This proved more complicated than he had perhaps anticipated, and Wahram and Swan left for the locks on their rooms’ floor before he was finished. Compensation for the ship would no doubt be a matter of ordinary Swiss insurance, and indeed it might come directly from the Venusians; some reward for their sacrifice was practically guaranteed, the captain was announcing as they took the elevator down; in any case it looked as if it was going to be necessary to abandon ship. The ship’s ferries and hoppers could hold all ten thousand people on board, but those qualified could and should make their escape in individual spacesuits, all of which had long-term supplies. In fact anyone who preferred suits to ferries could leave in a suit immediately on suit integrity check. All locks were available. They would be picked up within hours, he hoped, and it would become no more than an inconvenience, which would be regarded as heroic because it would save Venus. Only good things could follow from that. There was a necessity for speed to give their aid effectively, so unfortunately they would all be forced to operate under a three-g equivalent for the duration of their time on board. The inconvenience was greatly regretted, and assistance from the crew would be provided to all who requested it.

The announcement as it went on and on in its convoluted Swiss way was causing an uproar throughout the ship, which Swan and Wahram became aware of when they left their elevator on their floor. As they entered the lock room they heard voices calling out, seemingly throughout the ship, and they gave each other a look.

“Let’s stick together,” Swan said, and mutely Wahram nodded.

This flip was somehow more disorienting than usual, as if knowing it was anomalous made it into something like space sickness, or a dream in which one’s body floated away to disaster.

The bad feeling fell into another kind of nightmare when they got going again and the weight of their bodies fairly rapidly tripled. This was enough to drive everyone to the floor. People cried out at the shock of it, but the situation was understood, and after the first few moments most of the passengers rolled into a crawling position and did their best to crawl or roll or slither. Different methods were being tried, and some people were clearly having no success at all, lying there struggling as if pinned by an invisible wrestler.