The Eternal Flame

again the Gnat was receding—outpacing them in its orbit now, as the blast of air acted as a gentle brake on the Mite.

Ivo shut off the jet. They were separating from the Gnat so slowly that Carla could imagine Tamara stepping out through the hatch onto a fanciful sky-road, catching up with them effortlessly and handing them some item they’d neglected to pack. As for their rate of descent, that was too slight to discern at all. But the tiny reduction in their orbital velocity had reshaped their trajectory from a circle into an ellipse; in six bells, their altitude would be less by a factor of ten.

The whole flight plan they’d prepared relied on the assumption that the usual principles of celestial mechanics would keep working in the Object’s environs. Given the spectacular failure of traditional chemistry Carla wasn’t willing to take anything for granted, but all the evidence so far was that the orthogonal rock beneath them was producing the same kind of gravitational field as a comparable body made from ordinary matter. From the Gnat’s orbital period Tamara had estimated the Object’s total mass, and her figure was consistent with the kind of minerals Ivo’s spectra had identified on the surface. Rock couldn’t magically change into something entirely new just because you encountered it at a different angle in four-space. Indeed, one faction among the chemists maintained that ordinary matter ought to contain both positive and negative luxagens—in equal numbers, symmetrically arranged—and that the swapped rock in the Object would thus be literally identical to ordinary rock. Carla had had some sympathy for the notion on purely esthetic grounds—and it certainly would have made Silvano happy if it had turned out to be true—but the fate of Ivo’s projectiles had demolished that idea.

Comfortable? Ivo asked her.

She turned to him. Sure. Ivo looked composed, as far as she could judge from the sight of his face through his helmet. If all went well, for the next six bells they’d have nothing to do but watch the stars and the scenery. All the danger would be down on the surface—and the trick to staying sane until then was to accept that they couldn’t speed up their descent and get the whole thing over any sooner.

Carla gazed down at the gray plain directly below the Mite; though they were leaving this region behind, it was precisely where their spiral journey would finally deposit them. The craters here were wider and more numerous than elsewhere on the surface, bolstering the hope that the gray rock really would turn out to be as soft as powderstone.

As the plain slipped away she tried to imagine the collisions that had left these craters. The strange reaction with ordinary matter was probably not to blame; they looked too much like Pio’s craters, the product of nothing but like crashing into like at planetary speeds. The astronomers believed that the Object had started out deep within the orthogonal cluster a dozen light years away, then spent eons drifting alone through the void. Once, though, it must have been part of something larger.

What had torn that mother world apart? Perhaps a wildfire deep within it. A wildfire ignited how? By the tiny probability for every luxagen in every rock to break free from its energy valley—with the chance of escape mounting up over cosmic time. Some solids would be resilient, succumbing to nothing more than an inevitable slow corrosion, but others would suffer a kind of avalanche, with the change at one site shrinking the gaps between the energy levels for its neighbors, accelerating the process.

In the end, everything in the cosmos wanted to make light and blow itself to pieces. The only thing that differed was the time scale, set by the number of photons required to make the leap from solidity to chaos. But if the luxagens in most kinds of rock needed to make six or seven photons at a time in order to decay—six or seven far-infrared photons, each with the highest possible energy—what could possibly shrink that gap down to the single ultraviolet photon that Ivo’s spectra had revealed?

Carla’s gut tightened. She hadn’t been hungry since the journey began, but she found herself longing for the comforting aroma of groundnuts.

Other hands feeling steady? she asked Ivo.

Very, he assured her.

She wanted to see this reaction close up; the more she pondered the mystery, the more she ached to understand it. She just didn’t want to end up partaking in it herself.

Gyroscopes kept the Mite’s orientation locked against the stars, so as its orbit carried it around the Object, the Object in turn moved across the sky. Carla hardly needed to check the clock to know when they’d made half a revolution: the terrain that now stretched out above her head, its wide horizon upside down but level, rendered the whole configuration obvious.

It was her side of the Mite that was leading now, so it was her turn to brake the vehicle. She opened her air jet, counting the flickers beneath her fingertips, delivering a blast a little longer than Ivo’s. Their new orbit would be much rounder than the last one, but still sufficiently elliptical for its closest approach to bring them almost to the surface. Skimming above the powderstone plains, they could choose the most promising site and then kill their velocity entirely. Once they had fallen to within arm’s reach of the surface, resisting any further motion would require only the gentlest vertical thrust.

The ceiling of rock began tipping down toward Ivo’s side of the Mite, their descent propelling them around the Object ever faster. Carla found the sense of momentum more empowering than alarming; she’d had enough of waiting. She wanted to see a plain of orthogonal matter spread out beneath her, near enough to touch. This fragment of the primal world had traveled backward around the history of the cosmos; the world that had given birth to her ancestors had taken the opposite course. For a child of one to encounter the other would close that vast, magnificent loop—and the meeting that the Hurtlers offered with violence could here be made serene. With caution, serene.

Ivo took her hand. Did you see that?

What?

The flash, he replied.

Carla looked past him at the jagged brown rock, unchanging in the starlight. Perhaps the Object collided with specks of ordinary dust now and then. It was even possible that some fleck of material from the hull of the Gnat, or a particle of unburnt sunstone from their final burn, had just made its way to the surface.

She saw the next flash herself. It was less fierce than the ones they’d provoked from the Gnat, and much more diffuse—less a blazing pinprick than a brilliant daub of light. An ignition as dispersed as that wasn’t due to a fleck of anything.

What’s doing this? she asked Ivo. He didn’t have time to reply before the surface lit up again, a burst of blue-tinged flame spreading out across the rock, then quickly dissipating.

Us? he suggested.

Carla felt her muscles grow tense with fear, but his theory made no sense. How could they still be shedding anything, after the air had flowed over them for so long? Any loose material in their equipment or on their bodies should have been carried away into the void long ago by the relentless breeze.

What, exactly? she replied.

Ivo thought for a lapse or two, while another flash erupted on his left.

Contaminant in the air, he concluded.

Carla couldn’t see his face, which was turned toward the Object, but his posture was hunched in shame. Ivo had been responsible for filtering all the air they’d packed, ensuring that it contained no particulate matter. She couldn’t imagine him treating the task with anything but scrupulous attention.

But he wasn’t taking the blame for no reason; the symptoms lent his verdict a horrible plausibility. If the Mite’s would-be air shield was actually spraying traces of fine dust in all directions, that would explain why these ignitions were so much more dispersed than the ones brought on by the projectiles.

The flashes were coming every pause or two now, and the wall of rock was drawing closer. Carla struggled not to panic; the single worst thing they could do would be to aim an air jet straight at the surface in the hope of a swift ascent. All their tanks had to be treated as equally suspect: the contents of any of them touching the surface could engulf the Mite in a conflagration.

She made some quick calculations on her thigh. Jet four, six flickers, she suggested. Jet four was pointing back along their orbit; though the burst of air would be aimed horizontally, it would raise their