Greg Egan - The Eternal Flame

With one tap of her hand, Tamara deftly reversed the trajectories of the last crumbs that had been floating away from her mouth, then she took hold of the drive’s emergency start lever. If the reaction they provoked made a mockery of Carla’s guesses and blew the Object apart, the very alignment that had been intended to provide them with the most shielding from the blast would see the bulk of the flaming remnants propelled in the direction of the Gnat .

“One lapse to impact,” Ada announced.

Carla turned to the window. The powderstone plains were below the Gnat again; the rubble would strike an outcrop of calmstone on the opposite side. Calmstone meeting calmstone, putting paid to its name.

A soft blue halo appeared at the limb of the Object. A wildfire, come this far already? But then the halo expanded, creeping no closer as it slowly faded, and Carla understood: a plume of incandescent debris must have risen so high above the impact site and spread so widely as it soared into the void that its edges had become visible over the Object’s horizon.

Two bells later they’d moved far enough around the Object to see the plume clearly: a faintly glowing streak of gas and dust stretched out against the stars. Their trajectory was aimed right into it, so Tamara shifted the Gnat to a new orbit, its plane orthogonal to the axis of the plume.

Ada and Tamara began making observations, sighting beacons and timing the moments that various stars vanished behind the Object’s edge. Carla tried to catch up on her sleep as she waited for the verdict. When she closed her eyes she saw herself back on the Mite , descending into flames, but she was tired enough that it made no difference.

Two days later, the navigators had their first estimate of the change the calmstone rocket had produced. “We’ve removed three quarters of the Object’s velocity relative to the Peerless ,” Tamara announced. “A couple of scaled-down corrections should be enough to meet the target.” A perfect result was unattainable, but the target velocity would see the Object remain within reach for generations.

They waited one more day to be sure that the plume posed no danger, then Tamara tilted the Gnat ’s orbit enough to let them see the impact site. The crater was like nothing else on the Object: a flat bowl nearly a stroll wide, its floor a smooth black ellipsoid. The original terrain had been jagged, but the fireball that carved this shape had been oblivious to the varied heights of the boulders that stood in its way.

“So this is what our engines will do to the antipodal apartments when we use the new wonder fuel,” Ada said.

Carla buzzed, but the joke stung. “I’d better swap mine before word gets out.”

A few more blasts and the Object would be captured. They could return to the Peerless in triumph, their mission complete.

But what was the Object, right now? A vast new repository of energy—in a form that nobody knew how to handle, let alone safely exploit.

The fuel problem hadn’t been solved. Everything that made this new power source promising rendered it equally terrifying. And the fate of the Peerless , as ever, remained hostage to discoveries yet to be made.

26

Carlo looked on with a growing sense of dread as Ada and Tamara emerged from the airlock. Tamara was the leader; shouldn’t she have been the last to leave the Gnat ? He watched the navigators’ faces as they removed their helmets, bracing himself for confirmation of his fears.

They both looked tired, but happy. They did not look like bearers of bad news.

Addo ran forward to embrace his co, with Pio close behind. Tamara approached the rest of the welcoming party: Marzio, Carlo and Ivo’s son Delfino. “They’ll be up soon,” she said. “There were some records they’d packed away for the return journey that they suddenly decided they couldn’t leave for the decommissioning team to bring up.”

“Thank you,” Delfino said, his voice strained with relief. Carlo could understand why he hadn’t brought his children to the disembarkation; out of all the crew, Ivo had faced the greatest risk of not coming back.

“So what’s the news about the Object?” Carlo asked Tamara. Addo had spoken to the astronomers who’d seen it light up three times, but Carlo didn’t trust any remote interpretation of the events. “Rocket fuel or just rock?”

Tamara said, “Your co would murder me if I spoiled her chance to tell you the whole story. You’ll have to be patient.”

“But everyone’s fine?”

“Absolutely,” Tamara promised.

As Tamara spoke with Marzio, Carlo surveyed her appraisingly, looking for any sign that the journey might have done her harm. The most striking thing, though, was how much mass she’d gained. He’d been expecting that, but he was glad of the reminder; he didn’t want Carla to catch him noticing the change, forcing her to think about the struggle she’d be facing when they were meant to be celebrating her return.

Ivo climbed into view inside the airlock, a bundle of papers under one arm. Carla followed, similarly encumbered. “If they drop them they’ll be sorry,” Marzio said, bemused. “I don’t know why they couldn’t wait.” The papers began to flutter alarmingly as the airlock refilled, but with the entrance hatch closed any danger of losing them had passed.

Carlo approached the airlock. When Carla stepped through the doorway he took the papers so she could remove her helmet; the cooling bags made it impossible to extrude new limbs at will. Carlo noticed a neatly cut hole in the fabric over her left palm.

“Welcome back,” he said.

“I missed you,” she replied. Her words were strangely charged, like a threat or a confession.

The bag between them made a crinkling sound as they embraced. Carlo buzzed at the tickle of the creases.

“I managed to keep the Councilors away,” he said. “You won’t have to face any of them until the official reception.”

“Ha.” Carla relaxed slightly. “Poor Silvano isn’t going to be happy. Let me get this off, then we can go and talk.”

They stood together on the empty workshop floor, far enough from the others for a modicum of privacy. Carlo listened, entranced, to the results of the first experiments, but when Carla began describing her decision to join Ivo on the Mite it was hard to keep the horror from showing on his face. As the story went on he could feel himself losing the struggle.

“You almost died,” he said.

“But I didn’t.”

He tried to balance his anger against his gratitude that she’d survived, but the scales refused to lie still.

“Ivo could have gone down alone.”

“He was injured,” Carla replied. “I was the one who should have gone down alone. It was my job to replace him if he wasn’t in perfect health.”

Carlo didn’t reply. What could he do about this recklessness? Nothing. The whole thing was past.

He dragged his attention back to Carla’s words as she described her theory of luxagen annihilation; he even managed to ask half-intelligent questions as she summoned diagrams of the process onto her chest.

“When you turn everything sideways,” he said, “one of the photons that these annihilations ‘produce’ has to be there from the start?”

“Yes.”

“But that’s the ancestors’ reference frame, isn’t it?” Carlo realized. “So if they could watch all this, they’d claim that something emitted that photon in a completely separate process—to explain the fact that it came along just in time to bounce off the luxagen?”

Carla said, “That’s what you’d expect, though I wouldn’t swear to anything like that without a way to test it.”