Incandescence

Rakesh worked with Parantham to design a probe swarm to send into the ruins. Each probe would be about a micrometer wide, and would hop from asteroid to asteroid by riding the currents of the stellar wind — not the Interloper's feeble exhalation, but the overpowering breath of the neighborhood giants. On each rock they visited, the probes would gather energy from sunlight to feed a small band of exploratory nanomachines.

The wind couldn't carry the probes all the way from Lahl's Promise into the asteroid belt, so they had the workshop build half a dozen delivery modules, driven by ion thrusters, each carrying a kilogram or so of probes to scatter as they arced along the edge of the belt. These delivery modules would also act as information relays, with instruments to track the probes closely and elicit stored data from them.

The modules filed out of the workshop, flung away from the ship by centrifugal force before their thrusters lit up. Rakesh watched their blue exhaust trails through the cabin window. "Do you regret coming with me now?" he asked Parantham.

"Not at all!" she said. She seemed shocked by the question. "Why would I?"

"If the Steelmakers are dead, with no descendants. "

"Then that's sad," she said, "but history is full of sad stories. If there's no chance of meeting them face to face, I'll happily settle for archaeology. Archaeology in the disk is finished: every ruin has been tomographed down to the molecular level, every scrap of ancient language and every artefact has been interpreted to death. I was promised nothing but a rock full of microbes when I signed up for this, remember? And you expect me to be having second thoughts just because the sentient species we've discovered might have lasted less than one hundred and fifty million years?"

Rakesh couldn't argue with anything Parantham had said, but his own sentiments were very different. "Maybe at the back of my mind I thought the worst case scenario would be a thousand-year-long slog that ended with nothing but bacteria, while the best case would take us straight to the Planet of the Long Lost Cousins, who I could invite into the Amalgam to live happily ever after. Now that we've caught a glimpse of the real story, it seems that it's bacteria who would have had the best chance of living happily ever after."

He could easily picture his own village on Shab-e-Noor with a dark pinprick crossing the sky, the ground rumbling, an ominous lightness. Of course, that couldn't happen in the Age of the Amalgam; there was no conceivable cosmic threat out in the disk that could not be detected and neutralized. Such vulnerability had been relegated to history. Nevertheless, the image haunted him in a way that went beyond mere empathy for its putative victims. There was a chill in his bones at the recognition that, in the broadest sense, he'd stepped out from the shadow of the same kind of ax. His ancestors had been luckier than the Steelmakers, that was all.

The first wave of results from the probes came in while Rakesh was in the kitchen, cooking breakfast.

Dead microbes had been found in more than sixty per cent of the asteroids sampled so far. That figure was surprisingly high; either the biosphere of the Steelmakers' world had extended deep into the mantle, or the rubble that originated from the depths of the planet had been cross-contaminated by other debris, from closer to the surface.

The genome fragments and general morphology closely matched those of the microbes they'd found in the Aloof's meteor. Along with the isotope data, this left Rakesh with no doubt that they'd found their target. Half of the Interloper's asteroid belt consisted of rocks virtually identical to the one that had triggered their search.

"The Aloof should give us a treat and a scratch behind the ears now," he told Parantham as he filled her plate.

She stared at him as if he'd lost his mind.

"On my home world," he explained, "we have domestic animals that can find things by scent. You give them a whiff, then they go searching for something that smells the same."

"You don't have machines to do that?"

"Of course we do. But these animals enjoy it, it's part of their ancestry. If they don't get the chance to exercise their skills, they get sick with boredom."

"Like the gang back at the node?" Parantham suggested dryly.

"Well, yes." Rakesh hadn't intended the comparison to be taken literally, but he felt a momentary frisson of unease. "I suppose that's one theory we can't rule out: the Aloof took pity on us and offered us a chance to chase a strange new scent across their paddock."

"It doesn't show much pity if they only do it for a couple of people every million years." Parantham shook her head. "We're not their pets. They've kept a few secrets from us; good for them. It doesn't make them our superiors."