The Ringworld Engineers

“Know them? Know who?”

“Valavirgillin. Ginjerofer. The king giant. Mar Korssil. Laliskareerlyar and Fortaralisplyar. Herders, Grass Giants, Amphibians, Hanging People, Night People, Night Hunters… We’re supposed to kill 5 percent to save 95 percent. Don’t those numbers sound familiar to you?”

It was the puppeteer who answered. “The Ringworld’s attitude jet system is 5 percent functional. Teela’s repair crew remounted them over 5 percent of the arc of the Ringworld. Are these the people who must die, Louis? The people on that arc?”

Harkabeeparolyn and Kawaresksenjajok stared in disbelief. Louis spread his arms, helpless. “I’m sorry.”

The boy cried, “Luweewu! Why?”

“I promised,” said Louis. “If I hadn’t promised maybe I’d have a decision to make. I told Valavirgillin I’d save the Ringworld no matter what it took. I promised I’d save her, too, if I could, but I can’t. We don’t have time to find her. The longer we wait, the bigger the force pushing the Ringworld off center. So she’s on the arc. So’s the floating city, and the Machine People empire, and the little red carnivores and the Grass Giants. So they die.”

Harkabeeparolyn beat the heels of her hands together. “But this is everyone we know in the world, even by reputation!”

“Me too.”

“But this leaves nothing worth saving! Why must they die? How?”

“Dead is dead,” said Louis. Then, “Radiation poisoning. Fifteen hundred billion people of twenty or thirty species. But only if we do everything exactly right. First we have to find out where we are.”

The Puppeteer asked reasonably, “Where do we need to be?”

“Two places. Places that control the meteor defense. We have to be able to guide the plasma jets, the solar flares. And we have to disconnect the subsystem that causes the plasma jet to lase.”

“I have already found these places,” the Hindmost said. “While you were gone, the meteor defense fired, possibly to destroy the lander. Magnetic effects scrambled half my sensor equipment. Nonetheless I traced the origin of the impulse. The massive currents in the Ringworld floor that make and manipulate solar flares derive from a point beneath the north pole of the Map of Mars.”

Chmeee said, “Perhaps the equipment must be cooled—”

“Futz that! What about the laser effect?”

“Activity there came hours later: smaller electrical effects, patterned. I told you of this source. It is just over our heads, by ship’s orientation.”

“I take it we must disconnect this system,” Chmeee said.

Louis snorted. “It’s easy. I could do it with a flashlight-laser or a bomb or the disintegrator. Learning how to make solar flares will be the hard part. The controls probably weren’t designed for idiots, and we don’t have too much time.”

“And afterward?”

“Then we put a blowtorch against inhabited land.”

“Louis! Details!”

He would be speaking a death sentence for a score of species.

Kawaresksenjajok wouldn’t show his face. Harkabeeparolyn’s face was set like stone. She said, “Do what you must.”

He did. “The attitude jet system is only 5 percent operational.”

Chmeee waited.

“Operating fuel is hot protons streaming from the sun. The solar wind.”

The puppeteer said, “Ah. We flare the sun to multiply the fuel intake by a factor of twenty. Life forms beneath the flare die or mutate drastically. Thrust increases by the same factor. The attitude jets either take us to safety or explode.”

“We don’t really have time to redesign them, Hindmost.”

Chmeee said, “Irrelevant unless Louis is totally wrong. Teela inspected those motors while mounting them.”

“Yah. If they weren’t strong enough, she talked herself into adding an overdesign safety factor. Guarding against the mischance of a large solar flare. She knew that was possible. Doublethink!”

“To guide the flare is not necessary to us, merely convenient,” the kzin continued. “Let the laser-generating subsystem be disconnected. Then, if need be, Needle may be placed where we want the flare to fall, then used as a target: accelerated until the meteor defense fires. Needle is invulnerable.”

Louis nodded. “We’d like something a little more accurate. We’d do the job faster and kill less people. But… yah. We can do it all. We can do it.”

The Hindmost came with them to inspect the components of the meteor defense. Nobody talked him into that. The sensor devices they dismounted from Needle had to be operated by a puppeteer’s lips and tongue. When he suggested teaching Louis how to manipulate the controls using a pick and tweezers, Louis laughed at him.

The Hindmost spent some hours in the blocked section of Needle. Then he followed them out through the tunnel. His mane was dyed in streaks of a hundred glowing colors, and beautifully groomed. Louis thought, Everyone wants to look good at his own funeral, and wondered if that was it.

It wasn’t necessary to use a bomb on the laser subsystem. Finding the off switch took the Hindmost a full day and a disc-load of the dismounted instruments, but it was there.

The web of superconductor cables had its nexus in the scrith twenty miles beneath the north pole of the Map of Mars. They found a central pillar twenty miles tall, a sheath of scrith enclosing the cooling pumps for the Map of Mars. The complex at the bottom must be the control center, they decided. They found a maze of huge airlocks, and each had to be passed by solving some kind of design puzzle. The Hindmost handled that.

They passed through the last door. Beyond was a brightly lighted dome, and dry-looking soil with a podium in the center, and a smell that sent Louis spinning around, running for his life, towing a bewildered Kawaresksenjajok by his thin wrist. The airlock was closed before the boy started to fight. Louis batted him across the head and kept going. They had passed through three airlocks before he let them stop.

Presently Chmeee joined them. “The path led across a patch of soil beneath artificial sunlights. The automated gardening equipment has failed, and few plants still grow, but I recognized them.”

“So did I,” said Louis.

“I knew the smell. Mildly unpleasant.”

The boy was crying. “I didn’t smell anything! Why did you throw me around like that? Why did you hit me?”

“Flup,” said Louis. It had finally occurred to him that Kawaresksenjajok was too young; the smell of tree-of- life wouldn’t mean anything to him.

So the City Builder boy stayed with the aliens. But Louis Wu didn’t see what went on in the control room. He returned to Needle alone.

The probe was still far around the Ringworld, light-minutes distant. A hologram window, glowing within the black basalt outside Needle’s wall, looked out through the probe’s camera: a dimmed telescopic view of a sun somewhat less active than Sol. The Hindmost must have set that up before he left.

The bone in Harkabeeparolyn’s arm was healing slightly crooked; Teela’s old portable ‘doc couldn’t set it. But it was healing. Louis worried more about her emotional state.

With nothing of her own world around her, and flame about to take everything she remembered — call it culture shock. He found her on the water bed watching the magnified sun. She nodded when he greeted her. Hours later she hadn’t moved.

Louis tried to get her talking. It wasn’t good. She was trying to forget her past, all of it.

He found a better approach when he tried to explain the physical situation. She knew some physics. He didn’t have access to Needle’s computer and hologram facilities, so he drew diagrams on the walls. He waved his arms a lot. She seemed to understand.

On the second night after his return, he woke to see her cross-legged on the water bed, watching him