Carla understood: the flesh from his battered right arm hadn’t recovered, because he hadn’t actually managed to resorb it. He had gone through the motions of drawing it into his torso and making it appear that he was extruding an entirely new limb, but the injury had kept the damaged tissue stuck at its original site.
Ada said, “You can’t go out there with an injury.”
Caught out in his deception, Ivo had no reply. Carla couldn’t help feeling some relief that he had been spared the risk of the excursion—but Ada seemed altogether too pleased with the outcome. Ada had had the chance to revel in her own skills, as no navigator had for generations; why should Ivo be cheated of the same kind of fulfillment? What satisfaction was there in tossing sand at the Object, watching the fireworks, then running away? He was a chemist, and he’d come here to do chemistry: he needed to get as close to dirtying his hands as possible, without actually going up in flames in the process.
Carla heard herself saying, “I’ll go with him. I’ll be his right hand.”
“There’s no provision for two operators in the mission plan,” Ada replied, as if that settled it.
“I know how to use the Mite,” Carla said, stubbornness winning out over fear. “If Ivo had had to stay behind for some reason, I’d be the one charged with doing his job. But with a mild injury like this… he’s got too much experience to be replaced. We can add a second harness to the Mite, go out together, and I’ll be there to back him up if he needs it.”
Ada turned to Tamara, scowling. “You can’t possibly countenance this!”
Tamara said, “Ivo?”
“We can make it work,” he said, glancing at Carla with an expression of newfound respect. “I’m sure we can.”
“Let’s just try some rehearsals first,” Tamara said cautiously. “Each of you operating the Mite up here in orbit, with the other in harness as a passenger. If you strike any problems, the whole thing is off.”
“Of course,” Carla agreed. “That sounds fair.” She could feel her whole body growing charged with excitement, even as the voice of prudence in her head began howling in disbelief.
Ivo reached over and placed his palm against Carla’s, their skin making contact through the small apertures they’d cut into the cooling bags.
Ready? he wrote.
As I’ll ever be, Carla replied.
She glanced up at the Gnat, a dozen strides above them; Ada and Tamara were looking out through the window, their forms visible in the starlight but their faces impossible to read.
Carla rested the exposed fingertips of her lower right hand against the dials of the clock on the underside of the Mite, and wriggled a little to make herself more comfortable. She and Ivo were harnessed to a long flat plate that ran beside the main structure, held apart from it by six narrow struts. Struts and plate alike were hollow, and covered in fine holes; just as air flowed out through the fabric of her cooling bag, every part of the Mite was leaking, sending a thin breeze wafting out into the void in the hope of warding off danger. For all the sense this made, Carla still felt almost comically exposed—as if a solid hull like the Gnat’s might have offered them greater protection.
Ivo reached down and opened the valve on the air jet to his left. In itself, the kick of acceleration was barely noticeable; Carla merely felt as if one side of her harness had been drawn a little tighter. But when she looked up 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?