Starfire

32

The geometry had been set in place six days ago and fine-tuned every hour. The hollow tip of the conical shield pointed its arrow toward Alpha Centauri and maintained a fixed distance of half a light-second from Earth. Cusp Station hovered thirty thousand kilometers behind, precisely on the axis of the cone. Sky City in turn was locked in position one kilometer behind Cusp Station, whose newly installed field generators bathed the shield in a low-intensity glow mediated and diffused by the shield’s fine network of superconducting fibers.

Each particle bundle impinging on the shield would generate a burst of radiation, whose direction and signal frequency shift contained enough information for a precise trajectory to be computed. But to be useful, the calculation — like every other action — had to be made fast. Within seconds of hitting the shield, a free-flying particle bundle would reach Earth. Before then the detection data must be received on Sky City, necessary calculations completed, a loop field generated and sent on an interception trajectory, and the particle bundle caught and diverted safely away.

It was all possible — just. Maddy had watched the first tests, when the flux of particle bundles was still limited to a few thousand arrivals per second. Before the human eye could detect anything at all, each bundle was intercepted, netted, and curved away to miss Earth by thousands of kilometers. After a few hundred successful encounters, the conversation in the engineering control center became casual and upbeat. What no one mentioned — what Maddy wondered if most people knew — was the projected change in the situation as the storm approached its height. If the convergence of the beam was as strong as expected and the maximum arrival rate of particle bundles came even close to the projected value, the field generators would be unable to produce enough loop fields to handle the entire flood. At that point some of the bundles would begin to get through. Cusp Station and Sky City would have to be preferentially protected, since if their systems failed all defenses would be lost. But the consequence of that would be weaker protection at the edges of the shield, and thus of the parts of Earth, that lay behind them.

One thing was certain: The team on Sky City would know the worst before very long. The flux counters had begun their final climb. Storm maximum would occur in less than three hours, and long before that the defense system would be tested to the limit.

Maddy stared around the room, with its score of working engineers and data analysts. She wondered again: How far had the word spread of Wilmer Oldfield and Star Vjansander’s worst-case prediction? Did they all know?

She herself had told no one — but news, especially bad news, leaked out no matter how you tried to contain it. Yet she had seen no small groups closely-knit in conversation, and she had overheard not a dropped word.

On the other hand, she knew that John had heard Wilmer’s worst-case assessment — she had been with him at the time. And he now showed no hint of interest in anything beyond the task at hand. In fact, she was beginning to wonder if he had forgotten to make a promised announcement on a quite different subject. In the circumstances, that would be more than reasonable. A dozen murders must seem like nothing in the face of billions of deaths.

But John had not forgotten. When he finally spoke he was terse, almost casual. He addressed the room at large, his gaze intent on the displays. “We’re at zero minus two hours forty-one minutes, and are approaching one-tenth flux maximum. By the way, the particle storm seems to have produced an unexpected result. Because of it, they’ve found Doris Wu’s body.”

He seemed ready to leave it at that, leaning over the control panel and monitoring the final countdown, but Will Davis whistled loud through his front teeth and said, “You can’t stop there, boyo. Where, and how?”

“One of the last up-leg shuttles to Sky City. A million-to-one chance. If we hadn’t moved to our present position, the body might never have been found. The shuttle passed within forty meters, and a passenger made visual contact. They took her body on board and brought it here. It’s sitting in Cargo Bay Fourteen.”

Maddy was standing inconspicuously at the back. She said under her breath, Go on, go on. But John seemed intent on the controls.

“Did they find anything that might tell who killed her?” Torrance Harbish asked. Engineers from all around the center, their tasks for the moment ignored, looked up or moved closer.

“I don’t know,” John said. “I doubt it. Until this is all over, the security staff must have other things on their mind.” He looked up. “And so do we. Lauren, do you have those capture rates? Wilmer Oldfield is panting for them.”

“Right here. Shall I transmit?”

“Waste of time. Wilmer won’t look at the feed. Do you have time to take it to him?”

“I’ll find time. Where is he?”

“At the back of the water buffer. He and Star want to compare the bundles they get now with what they caught during the blip storm.”

“I hope the results they’re getting make more sense than mine do,” Amanda Corrigan said. She had three separate displays running in front of her. “We have a set of quickie Sniffers a few light-days out, and they’re showing a stronger storm convergence toward Sol than we’ve ever seen. But the counts I’m making locally fail to confirm. Both sets of data can’t be right. Take a look. Where are the bundles?”

The first display was a simple two-axis graph. The horizontal axis showed distance from Sol in astronomical units. The vertical axis was estimated beam area. As the storm approached the solar system, the area decreased dramatically. The. Alpha C storm was homing in on the solar system.

The second display was a table of total beam area versus predicted particle count per second at Sky City. The third display was another graph, with time as the horizontal axis and particle count as vertical axis. Both predicted and observed counts were shown. The predicted count rose rapidly at the time of maximum flux, and fell away as fast beyond it; the observed count went only up to the present time, but at the moment it was close to constant over time and looked nothing like the predicted peak.

John Hyslop gave the curves and tables in front of Amanda a cursory glance. “I’ve no time to look at them now. Get them to Wilmer and Star, let them figure it out. Matching predictions and observations isn’t our business. Our job is to deal with whatever arrives.”

He caught Maddy’s eye. She wondered if he could possibly be as calm as he looked. She surveyed the whole information center, with people constantly hurrying in and out, and found everyone busy and preoccupied. But she saw no sign of nervousness. The only nervous one was Maddy herself — maybe because she had too little to do.

She waited a few more moments, then quietly slipped out of the room. She was no help here, an engineering nonentity surrounded by the pick of the solar system’s engineers. But somewhere on Sky City there must be someone who needed assistance. If it was not true now, it would be when the storm arrived.