“I’ve never seen anything like it,” Ivo declared. “No ordinary rock burns with a narrow peak brighter than all the other light from the flame.”
“Let alone just one peak,” Carla added. “The total amount of energy a luxagen needs to gain in order to escape from calmstone would be something like two dozen times greater than the jump corresponding to that ultraviolet line. You’d expect a liberator for calmstone to modify the energy levels so the total gap was bridged in a lot of small steps—but there’s no reason why all of those steps should turn out to be identical in height!”
Ada said, “And yet, there it is: one lonely peak.”
Ivo launched a second scrag of calmstone, this time at the red-tinged portion of the Object’s southern lobe. The terrain here looked as if it was covered in firestone; watching through the theodolite, Carla braced herself for the sight of a wildfire, if not a full-blown Gemma event.
Three pauses and five flickers after the impact, there was a single, brief pinprick of radiance.
When Ivo extracted the paper from the spectrograph, there were some minor differences across the visible frequencies but the spectrum was dominated by exactly the same ultraviolet peak as before.
Ivo repeated the experiment, choosing two more regions of the Object with their own distinctive appearance. Then he switched the projectile from calmstone to hardstone, then powderstone, clearstone, mirrorstone, firestone and sunstone. In two dozen and four variations, the delay before the flash was sometimes a little longer or shorter, and the visible part of the spectrum showed clear differences that depended on the particular area being targeted on the surface. But in every case, a single ultraviolet line blackened the paper at exactly the same position.
Carla could offer no explanation, and Ivo was equally perplexed. Ivo went so far as to aim the spectrograph at a lamp inside the cabin, to see if the ubiquitous line was really just the product of some bizarre flaw in the optics. It wasn’t.
“Take away the ultraviolet line from this spectrum,” he said, holding up a strip of paper he’d exposed to a flash from the red rock of the southern lobe, “and take away the liberator lines from this one.” He grabbed the test strip he’d made from the lamp. “Apart from those features, they both look the same: burning firestone.”
“So firestone is firestone, luxagen-swapped or not,” Ada said. “Once it’s actually burning, the light is identical, just as Nereo’s theory would predict.”
Carla said, “But the process by which the Object’s firestone is being set alight looks nothing like the way a liberator acts on ordinary firestone. And it’s completely indiscriminate: it acts the same way with every mineral. It doesn’t care about the detailed structure of any of these solids—their geometry, their energy levels. It just does its magic trick and pfft…”
Tamara finally took off her blindfold. “Whether or not we understand the ignition process, surely this is an answer to the fuel problem? Every scrag of the Object can be made to burn! A little too easily for comfort… but if we can slow this thing down enough to keep it in reach, the next generation can deal with the practicalities.”
“Or the next generation could catch up with it and fetch it back,” Ada suggested. “They’ll have had time to think deeply about the results we’ve seen, and work out what’s really going on. We know the Object’s trajectory with very high precision now. We can’t lose track of it.”
Tamara almost seemed swayed, but then Ivo interjected angrily, “We came here to capture the Object! That was the mission the Council approved: to take samples, to do calorimetry, then to trigger a blast that would leave this thing motionless. If we give up now, all we’ll be bequeathing our descendants is a longer journey and a more difficult version of the task we should have done ourselves. We’ve had three generations of theorizing about orthogonal dust, and that’s left us none the wiser. The only way to understand this material is by experiment.”
Ada said, “You’ve just completed a whole set of experiments! Do you really want to get any closer to something that can set every tool and container you have on fire?”
“I have the air tools,” Ivo insisted.
“Which can only carve powderstone,” Ada replied.
Ivo rummaged through the spectra, then pulled out one strip. “Here! The gray mineral, in the north. As you said, luxagen-swapped or not, the basic properties of a substance are the same. Except for the ultraviolet line, this spectrum is the spectrum of powderstone! To the eye, this rock looks like powderstone! Physically, there is no reason why it shouldn’t be every bit as soft as powderstone.”
Ada and Tamara looked to Carla. “I can’t argue with that,” she said. “It ought to have the same mechanical properties as the ordinary mineral. But from what we’ve just seen, if a speck of it touches anything—”
Ivo said, “There’ll be air flowing out of my cooling bag, constantly. The Mite has an air shield around it too. I’ve practiced this: I know I can take a sample of powderstone without touching it.”
Tamara was silent for a while. “All right,” she said reluctantly. “If you’re still confident that you can do this, I’m not going to stand in your way.”
She reeled in one of the guide ropes to make some room, then Carla helped Ivo slide the Mite out of its storage bay and bring it to the middle of the cabin. It was less a vehicle in its own right than a kind of chemistry workbench fitted out for the void, with air jets attached. As Ivo’s understudy, Carla had had her own rehearsals with a mock-up of the thing, maneuvering it around the Peerless and practicing the descent from orbit. After a few days she’d become quite comfortable with the way it moved—but she’d lost count of the number of gentle collisions she’d had with the mountain.
She moved aside to let Ivo run through his equipment checks. Ada watched the process with an expression of contained disapproval, though Carla suspected that what she most resented was Tamara ignoring her advice. Ada had prepared herself to lead the mission, to bear the final responsibility for everything they did. However much she’d rejoiced to learn that her friend was alive after all, it must have been difficult to relinquish that commanding role.
Tamara told Ivo, “I want you to limit yourself to the powderstone outcrop. Trying to get samples anywhere else will be too difficult; that one mineral will have to serve as a surrogate for all of them.”
“I can live with that,” he replied. He was testing the recoil balance for his air blades, hovering beside one of the remaining guide ropes, proving that he could maintain a fixed separation from it even as he waved the invisible cutting jets about. “Whatever’s responsible for that ultraviolet line looks like the strongest reaction in every case. So if we can quantify the energy release for powderstone—”
Ada said, “What’s wrong with your right arm?”
“Nothing.” Ivo shut off the cutting jets and held up the accused arm for inspection. “Why would you even—?”
“You’re favoring the left one,” Ada said flatly.
“That’s not true,” he protested. “This is a whole new limb! Since I re-extruded it there’s been no pain at all.”
Tamara said, “Hold onto the rope and give the Mite some spin around a vertical axis, using your right hand.”
Ivo buzzed, offended. “Why would I ever need to do that? If I need to adjust the orientation, that’s what the air jets are for.”
“I know,” Tamara said quietly. “I just want to see how strong that arm is.”
Ivo gripped the rope beside him as she’d asked, and reached for the edge of the Mite with his right hand. He managed to get it spinning, but his struggle to ignore the pain was obvious now.