“Societies only have waste products while acquiring fresh raw material remains a cheaper option than recycling,” Samuel said. “This close to the star, the diskcities are extremely rich in energy. There can be few waste molecules that cannot be reprocessed into something useful.”

“Even so, they must have strong prohibitions on reproducing. I see a circle of life like this, and all I can think about is a culture growing in a dish.”

“That analogy doesn’t hold for sentient life. The Tyrathca nature is inclined to logically empowered restrictive behaviour. After all, they regulated themselves perfectly on a ten thousand year arkship voyage. This situation is no different for them.”

“Don’t assume their dominions are uniform,” Sarha said. “I’m detecting some areas on the disk with a much higher temperature than the others, their thermal regulation has completely broken down. Heat from the star is flowing straight through. They’re dead.”

“Maybe so,” Beaulieu said. “But there’s still a lot of activity down there. We’re being bombarded with radar signals from every section. A lot of dominions are very interested in us.”

“Still no ship launch,” Joshua said. “No one’s trying to intercept us before we reach Anthi-CL.” He accessed the sensors to watch Tojolt-HI growing against the radiant crimson expanse of the giant star. Apart from the scale involved, it was similar to their approach to the antimatter station. A jet-black, two-dimensional circle cutting right into the photosphere. The cold light of the nebula behind them was unable to illuminate a single feature on the back of the diskcity. Only Lady Mac ’s sensors could reveal the topography of mountainous towers pointing blindly away from the disk’s median level. The flight computer’s cartography program was having trouble compiling an accurate chart; the glare of electromagnetic emissions aimed at them was interfering with their radar return.

“What are they all saying?” he asked Oski.

“I’m running a keyword discrimination program on the datatraffic. From the samples so far, it’s all pretty much the same. They all want us to dock at their own section of the diskcity, and each claims to have the greatest resources, as well as unique information.”

“Any threats?”

“Not yet.”

“Keep reviewing it.”

Lady Mac flipped over and began decelerating.

Sensor data on Tojolt-HI built up slowly during the approach phase, giving the crews on Lady Mac and Oenone a good idea how the massive diskcity was constructed. The median sheet which formed the actual disk itself was an amalgamation of dense webs made up out of tubular structures, varying from twenty to three hundred metres in diameter. Though closely packed, they didn’t touch except at end junctions; the gaps between them were sealed over with foil sheets, preventing any of the red giant’s light from penetrating and diluting the umbra. Individual web patterns were principally circular, also varying enormously in size, and overlapping in contorted tangles. Spectrographic analysis found the constituent tubes were mostly metallic, with some silicon and carbon composites stretching across large areas; over five per cent were crystalline, radiating a wan phosphorescence out towards the nebula. There were regions, spread at random over the darkside, where the tangle of pipes swelled out into complex abstract knots several kilometres wide. It was as if the tubes had been subjected to severe lateral buckling, though the radar image couldn’t determine any fractures.

The dense shade of the darkside was inevitably dominated by the thermal transfer machinery. Radiator panels stacked in kilometre-high cones stood next to circular fan towers of faint-glowing fins, minarets of spiralling glass tubes with hot gases rushing through them competed for root space with encrustations of black pillars like a spiky crystal growth, whose sheer ends fluoresced coral pink. Their meandering ranks formed mountain ranges to rival anything thrown up by planetary geology, running for hundreds of kilometres along the webs. Straddling the valleys between them on long stilt-like gantries were giant industrial modules. Dark metal ovoids and trapezohedrons of machinery, their exterior surfaces a solid lacework of pipes and conduits, rising to a crown of heat-dissipation fins or panels (a direct ancestry could be traced to the machinery on Tanjuntic-RI). Although the diskcity had an overall uniformity bestowed by its basic web design, no region or structure was the same, technologies were as heterogeneous as shapes. The standardisation and compatibility synonymous with the Tyrathca had clearly broken down between the dominions millennia ago.

As they drew closer, more movement became visible across the darkside. Trains, made up from hundreds of tanker carriages and kilometres in length, slid slowly along the valleys and embankments between the thermal transfer systems. Their rails were an open framework of girders; suspended above the tubes and foil sheets of the disk, undulating like a roller coaster track, dipping down to merge with the larger tubes, allowing the trains to run inside them, then rising up the stilt legs of industrial modules to pass straight through the middle.

“Who the hell built this place?” Ashly asked in bemusement as the grey pixels built up into a comprehensive image in this neural nanonics. “Isombard Kingdom Brunel?”

“If it works, don’t try and fix it,” Joshua said.

“There is more to it than that,” Samuel said. “Tojolt-HI is not a declining technology. They have selected the simplest engineering technology which can sustain them. Whilst humans would no doubt progress to developing a full Dyson sphere over fifteen thousand years, the Tyrathca have refined something that requires the minimum of effort to maintain. It does have a kind of elegance.”

“But it still fails repeatedly,” Beaulieu said. “There are dozens of dead sections across the disk. And each failure would cost them millions of lives. Any sentient creature should try to refine its living environment to something less prone to accident, surely?” Samuel shrugged.

The Anthi-CL dominion began issuing instructions for Lady Mac ’s final rendezvous coordinate. A blueprint they transmitted identified a specific section of the rim, which the flight computer matched up to the sensor image. The Anthi-CL dominion wanted them to keep station two kilometres out from a pier-like structure protruding from the edge.

“How is the translation program update coming on?” Joshua asked Oski. “Do we know enough to communicate directly now?”

“It’s integrated all the new terms we’ve encountered so far; the analysis comparison subroutine response time is down to an acceptable level. I’d say it’s okay to try and talk to them.”

Lady Mac ’s drive thrust was reducing steadily as she drew level with the plane of the disk. In comparison to the desolate solidity of the darkside, the rim appeared to be unfinished. It bristled with slender spires and protruding gantry platforms wrapped in cables. Clumps of tanks and pods were attached to various open frame grids.

“At last,” Sarha said. “That’s got to be a ship.”

The vessel was docked to the rim a hundred kilometres along from their rendezvous coordinate. It had a simple profile, a pentagon of five huge globes scintilating with a soft gold and scarlet iridescence under the gas-giant’s illumination, each one at least two kilometres in diameter. They surrounded the throat of an elongated funnel made from a broad mesh of jet-black material; its open mouth was eight kilometres across. There was no recognizable life support section visible from Lady Mac ’s current position.

“Picking up a lot of very complex magnetic fluctuations from that thing,” Liol said. “Whatever it does, there’s a lot of energy involved.”

“If I didn’t know better, I’d say it was a Bussard ram-scoop,” Joshua said. “It was a neat idea, pre-ZTT era interstellar propulsion. Use a magnetic scoop to collect interstellar hydrogen, and feed it direct into a fusion drive. A cheap and easy way to travel between stars, you haven’t got to worry about carrying any on-board fuel. Unfortunately it turns out the hydrogen density isn’t high enough to make it work.”