Cascade Point

Chou was silent for a moment. "If we can't stop this, how long do we have?"

"Until the explosion? A year, probably. If our theory is right, that is; if it isn't I have no idea. Of course, Firefly will be far too hot to approach long before that."

"Dr. Carter... can we stop Firefly?"

Carter shook his head slowly. "I can't see any way to do it. No way at all. My God, Senator, what's going to happen to all those people?"

"We won't be able to evacuate them in time. Besides, where would they go? Ceres and Hestia can't absorb any excess population. Maybe we can tow the Space Colonies out of Earth orbit into the asteroid belt; they should be able to survive out there." Chou shook his head, his face a mirror of horror and pain. "But Earth has no chance."

"No."

Chou looked up. Carter avoided his eyes. The blame is not yours, Doctor," the Senator said. "We—mankind's leaders—made the final decision on Firefly. Ours is the responsibility. Not that laying blame helps any." He sighed. "Ironic, isn't it? For the past three centuries we have been continually worried about ru

Something brushed the edge of Carters mind. "Say that last again, will you?"

"What? I just said our final crisis was too much energy, whereas in the past—"

"Too much. Too much." Suddenly the fatigue was gone, dislodged from his mind by a maelstrom of new thoughts and ideas. Fumbling out his intercom, he keyed for general 'cast. "This is Carter. All senior staff, report to conference immediately."

"Dr. Carter...?"

Carter glanced up and smiled slightly at the Senators uneasy expression. "Don't worry, I haven't crossed my circuits; at least, not yet. You just reminded me that there are two sides to this problem and we've been ignoring one of them. Excuse me now, I have to think."

He was still scribbling on a pad when the others arrived and took their places. "All right," he said. "First of all, has anyone else come up with anything?"

No one spoke, but Carter could feel the drop in tension throughout the room as they realized there was a hidden promise in his question. "I don't guarantee this," he warned them, "but see what you think. So far we've been concentrating on getting more mass into Firefly. Maybe we can hit the problem from the other direction; namely, to decrease the density of the particle cloud that's keeping the neutrons out in the first place."

"But it's not like a real, stationary cloud," Rurik objected. "It's self- regenerating, more on the order of a bathtub with a faucet at one end and a drain at the other."

"Exactly. So we're going to enlarge the drain. What is the cloud composed of, gentlemen?"

"Subatomic particles," Galton said. "Positive and neutral, mostly."

"Right," Carter agreed. "Why no negative ones? Because the positive plates that hold Firefly itself in place rip away any negatives as soon as they're formed. Conversely, the plates tend to keep the positives near Firefly. The neutrals don't care either way." He handed a sketch to Mahler. "Felix, I propose setting up a pair of negatively charged plates a few meters from Firefly and where they won't block the neutron beams. What I want is to set up an extra electric field that will pull the positive particles away from Firefly without risking moving the black hole itself. Can it be done?"

Mahler frowned at the sketch for a moment. "It'll be tricky," he said. "Any extra charge near Firefly will change the field of the main plates. What we need is stable equilibrium right at Firefly's position and a small nonzero field a few angstroms away. We'll probably need curved electrodes of some kind; the computer can figure the shape for us."

"But be damn careful with that field," Rurik spoke up. "The black hole has got to be at a stable equilibrium point or we'll lose it."

"I'll set up the programming myself," Mahler said, making notes beside Carter's sketch.

"Doc, what about the neutral particles?" Rossetti asked.

"I think we're stuck with them," Carter admitted. "But if we can decrease the density of positives even a little it may be enough." The excitement he had felt a few minutes before was wearing off and fatigue was begi

Carter had intended only to rest his eyes for a moment before rejoining the others. It was with some shock, therefore, that he dragged himself from a nightmarish dream two hours later to find himself still sitting at the deserted conference-room table. Blinking the sleep from his eyes, he pulled out his intercom. "Carter to control room," he said thickly.

"Rurik here, Ray." "What's going on up there? Why did you let me sleep this long?"

"We thought you needed the rest. The new electrodes have been made and tested, and Galton and Telema

"In a minute." Sleep was begi

"But the photons don't carry enough mass to make any real difference. Remember?"

"Don't care about the mass. The X-ray photons will get trapped into orbits around Firefly, either spiraling in or being absorbed by particles in the cloud. Most of those particles will be neutrals, since we're pulling away the others. Any particle that absorbs a photon will gain its kinetic energy and momentum."

"I understand," Rurik nodded excitedly. "The neutrals will tend to move away from the black hole faster. Just like heating up a gas and making it expand, really."

"Right. I admit it'll be a small effect—Firefly's own X-ray output is heating up that particle cloud far more than our lasers could ever hope to—but it may be worth doing, anyway."

"Agreed. We'll get on that right away."

Deep in Carter's subconscious the decision was made that he had done all that he could and that Firefly's fete was now in the hands of the universe. He barely managed to turn off his intercom before he was once more deeply asleep.

—

It was another four hours before he again awoke. This time he had the strength to go to the control room. One look at the meters was enough. "We did it," he murmured, half to himself.

Rurik swiveled in his seat at the main board. "You're awake," he said u

"That reminds me. Did you tell me Galton was helping to install the new plates?"

Rurik lowered his eyes. "He insisted on going. I think he felt—well, responsible for the runaway." "He's an operator, not a tech," Carter growled. "He had no business going out there." He looked around the room. "Where is he, anyway?"

There was a long moment of silence. Then Rossetti spoke up quietly. "He and Telema

Carter stared at him, a cold fist squeezing his heart. "Oh, God. I never even thought of that."

"They knew the risk," Rurik said. "They also knew it had to be done."

"A high price to pay, but it bought the lives of Earths billions," Senator Chou added.