Greg Egan - The Eternal Flame

After a frantic sweep she finally found it: a silhouette against the background of stars, absurdly huge under this modest magnification. She ran her fingertips over the dials of the clock, then wrote the time and the coordinates on her forearm. The silhouette was moving rapidly, blacking out each streak of color behind it for no more than four pauses. It was hard to discern its precise shape, as it seemed to be spinning as it moved, complicating its outline.

This was no interloper; any object crossing the sky so rapidly had almost certainly come from the Peerless itself. Tamara reached over and pulled a lever to ignite the shielded sunstone lamp that powered the coherent light source. The device was just a test rig that Romolo had loaned the astronomers, to try out on the first of Marzio’s new beacons. The tuning mirrors tended to slip out of alignment, and she had to spend a couple of lapses adjusting them until the monitoring screen showed a steady pin-prick of red light. That was from a tiny portion of the beam; the full radiance would have blinded her. She slipped the mirror into place that sent the beam to a second small telescope mounted parallel to the main instrument.

A red spot appeared in the center of the silhouette—bright enough to prove that the thing was small and close, not large and distant. Tamara guessed it was at most a few strides across—a rock that had broken away from the mountain’s slope, or something discarded from an airlock.

But that made no sense. The mountain’s spin could cast objects away, but they’d always be traveling at right angles to its axis. Anything flung off by centrifugal force would, in short order, end up motionless against the stars, a retreating image fixed on the observatory’s horizon. Not only was this thing above the horizon, it was ascending. Another force must have altered its trajectory after it had left the mountain.

It was a person , Tamara realized. Someone must have fallen from one of the fire-watch platforms. They’d tried to use their air jet to get back, but they’d panicked and become disoriented.

She tore off her harness and scrambled for the exit.

Ada was still in the office. Tamara explained the situation, and gave her the times and coordinates she’d need to extrapolate the watcher’s trajectory into the future.

“I want you to go up and keep the light source trained on them. I’ll follow the beam out.”

Ada said, “No one’s been reported missing. There’s a dead-man alarm on every platform; people don’t just disappear into the void.”

“What did I see, then?” Tamara demanded. “Explain it to me!”

“I have no idea.” Ada’s expression changed suddenly. “Unless it was deliberate?”

Tamara understood her meaning: someone on fire watch who’d been advocating too loudly for the wrong kind of vote might have had a surprise visitor. The alarm would present no problem: the watchers themselves disabled it for every change of shift.

“Track the beam for me?” Tamara pleaded.

Ada said, “This is crazy! How are you going to see it?”

“I’ll improvise. Please? ”

Ada gave up arguing. “Be careful,” she said.

She headed for the observatory. Tamara headed for the airlock.

Out on the slope, Tamara clambered along the guide rails leading up from the airlock until the dome of the observatory came into view. Even from this distance she could see a faint red glow on one of the clearstone panels: scattered light from the beam. She released the rails, waited a moment to fall safely clear of them, then used the air jet strapped to her body to cancel the sideways velocity she’d acquired on her way out to the airlock. The rails receded into the distance as the rock of the slope swept past beside her.

She fired the jet again, to take her toward the peak. Once she was level with the dome she slowed herself, then she used a quick burst to move straight toward the red glow. She struck the dome squarely on the panel she’d been aiming for and gripped the edge tightly with six hands, then glanced down and saw Ada gawping up at her. Tamara freed one hand to wave at her, then another to help tug an empty cooling bag out of her tool pouch and spread it across the panel. The beam showed up as a dazzling red disk half a dozen scants wide, shimmering through the fabric.

She didn’t need to use the jet: she pushed off from the dome, rising slowly into the void, holding the white banner stretched out below her. She ignored the stars, the dome, the mountain, fixing her attention on the way the light was drifting across the cooling bag.

She aimed the nozzle of the jet carefully, then opened it for a fraction of a pause. The red disk jerked wildly toward the edge of the fabric, and for a moment she thought she’d lost it, but when she stretched her left arm out a bit further the light reappeared.

Once it was clear that she wouldn’t need another correction immediately, Tamara opened her rear eyes and searched for the fire-watcher’s silhouette. She trusted Ada to perform her task flawlessly, but if the watcher hadn’t noticed the beam alight on them—or in their state of confusion had failed to grasp its meaning—they might have done the worst thing possible and fired their air jet again, changing their trajectory.

Tentatively, she slid the banner out of the beam, allowing the light to continue unobstructed to its original target. For a long time she could see no sign of it above her, but then she picked out a faint red speck surrounded by blackness. The silhouette had been there all along, but the trails behind it were so dim that she could barely make them out; little wonder she’d missed the gaps in them. She waited as long as she dared, hoping the reassuring message of the beam would get through, then she spread the banner out again to check her own alignment.

Ada’s tracking was perfect, and the watcher was proving to be an obliging partner in the rendezvous. There were grimmer reasons than presence of mind why someone lost in the void might stop trying to change course, but Tamara didn’t want to dwell on them.

The next correction she made would need just the briefest puff of air; Tamara’s fingers almost cramped with anxiety at the thought that she might open the valve too wide or for too long. The disk of light jittered, mapping every fluctuation in the nozzle’s tiny thrust, but when it settled it was closer to the center of the banner than ever. She chirped to herself to release the tension, then gazed in sudden wonder at the steady red glow. The navigators who’d brought the Peerless onto its orthogonal course had worked the marvel of their age, but none of them could have imagined following a beam like this across the void. She was at least four saunters from the mountain now, but the red disk had barely increased its width and was barely diminished in brightness.

The third correction was no less daunting, but she didn’t foul it up. Tamara imagined a daughter beside her, learning this skill from her, sharing her delight in the intangible red guide rope.

She could see the figure above her clearly now, almost certainly a woman, spinning slowly in the starlight. Tamara let the beam fall on the woman’s cooling bag, but it elicited no response.

Agonizing over their relative velocity would only waste time; she was sure it would not be injuriously high. She stuffed the empty cooling bag back into her tool pouch to free two more hands, aimed herself straight at the woman, and prepared to grab her.

Their bodies collided with a beautiful dull thwack, and Tamara closed six arms around her in a tight embrace. For a moment she almost let go in shock: the skin pressed against her through the fabric was alarmingly hot. She felt around the woman’s back for any trace of air wafting out; there was none. There was no canister attached to the bag, and no air jet either. Quickly, Tamara tugged her spare canister out of its pouch and snapped it onto the inlet. Air flowed through the bag, sending a warm breeze spilling out into the void.