some relief, he darkened the cabin so that he could see Deimos, dwindling at surprising speed. The higher of the two Martian moons was a dark, bristling lump infested with armaments, belted by the bright, window-studded band of the moving ring. For the last nine years, Deimos was all he had known, but now he could encompass it within the arc of his fist.
‘Not just her prisoner,’ Voi said. ‘No one else came back sane from the Conjoiners. She never even tried to infect you with her machines.’
‘No, she didn’t, but only because the timing was on my side.’ Clavain was reciting an old argument now, as much for his own benefit as Voi’s. ‘I was the only prisoner she had. She was losing the war by then; one more recruit to her side wouldn’t have made any real difference. The terms of ceasefire were being thrashed out and she knew she could buy herself favours by releasing me unharmed. There was something else, too: Conjoiners weren’t supposed to be capable of anything so primitive as mercy. They were Spiders, as far as we were concerned. Galiana’s act threw a wrench into our thinking. It divided alliances within high command. If she hadn’t released me, they might well have nuked her out of existence.’
‘So there was absolutely nothing personal?’
‘No,’ Clavain said. ‘There was nothing personal about it at all.’
Voi nodded, without in any way suggesting that she actually believed him. It was a skill some women had honed to perfection, Clavain reflected.
Of course, he respected Voi completely. She had been one of the first human beings to enter Europa’s ocean, decades back. Now they were planning fabulous cities under the ice, efforts she had spearheaded. Demarchist society was supposedly flat in structure, non-hierarchical; but someone of Voi’s brilliance ascended through echelons of her own making. She had been instrumental in brokering the peace between the Conjoiners and Clavain’s own Coalition. That was why she was coming along now: Galiana had only agreed to Clavain’s mission provided he was accompanied by a neutral observer, and Voi had been the obvious choice. Respect was easy. Trust, however, was more difficult: it required that Clavain ignore the fact that, with her head dotted with implants, the Demarchist woman’s condition was not very far removed from that of the enemy.
The descent to Mars was hard and steep.
Once or twice they were queried by the automated tracking systems of the Satellite Interdiction Network. Dark weapons hovering in Mars-synchronous orbit above the nest locked on to the ship for a few instants, magnetic railguns powering up, before the shuttle’s diplomatic nature was established and it was allowed to proceed. The Interdiction was very efficient; as well it might be, given that Clavain had designed much of it himself. In fifteen years no ship had entered or left the Martian atmosphere, nor had any surface vehicle ever escaped from Galiana’s nest.
‘There she is,’ Clavain said, as the Great Wall rose over the horizon.
‘Why do you call “it” a “she”?’ Voi asked. ‘I never felt the urge to personalise it, and I designed it. Besides… even if it was alive once, it’s dead now.’
She was right, but the Wall was still awesome to behold. Seen from orbit, it was a pale, circular ring on the surface of Mars, two thousand kilometres wide. Like a coral atoll, it entrapped its own weather system: a disc of bluer air flecked with creamy white clouds that stopped abruptly at the boundary.
Once, hundreds of communities had sheltered inside that cell of warm, thick, oxygen-rich atmosphere. The Wall was the most audacious and visible of Voi’s projects. The logic had been inescapable: a means to avoid the millennia-long timescales needed to terraform Mars via such conventional schemes as cometary bombardment or ice-cap thawing. Instead of modifying the whole atmosphere at once, the Wall allowed the initial effort to be concentrated in a relatively small region, at first only a thousand kilometres across. There were no craters deep enough, so the Wall had been completely artificial: a vast ring-shaped atmospheric dam designed to move slowly outward, encompassing ever more surface area at a rate of twenty kilometres per year. The Wall needed to be very tall because the low Martian gravity meant that the column of atmosphere was higher for a fixed surface pressure than on Earth. The ramparts were hundreds of metres thick, dark as glacial ice, sinking great taproots deep into the lithosphere to harvest the ores needed for the Wall’s continual growth. Yet two hundred kilometres higher, the wall was a diaphanously thin membrane only microns wide, completely invisible except when rare optical effects made it hang like a frozen aurora against the stars. Eco-engineers had seeded the liveable area circumscribed by the Wall with terran genestocks, deftly altered in orbital labs. Flora and fauna had moved out in vivacious waves, lapping eagerly against the constraints of the Wall.
But the Wall was dead.
It had stopped growing during the war, hit by some sort of viral weapon that crippled its replicating subsystems, and now even the ecosystem within it was failing; the atmosphere cooling, oxygen bleeding into space, pressure declining inevitably towards the Martian norm of one seven-thousandth of an atmosphere.
He wondered how it must look to Voi; whether in any sense she saw it as her murdered child.
‘I’m sorry we had to kill it,’ Clavain said. He was about to add that it had been the kind of act that war normalised, but decided the statement would have sounded hopelessly defensive.
‘You needn’t apologise,’ Voi said. ‘It was only machinery. I’m surprised it’s lasted as long as it has, frankly. There must still be some residual damage-repair capability. We Demarchists build for posterity, you know.’
Yes, and it worried Clavain’s own side. There was talk of challenging the Demarchist supremacy in the outer solar system; perhaps even an attempt to gain a Coalition foothold around Jupiter.
They skimmed the top of the Wall and punched through the thickening layers of atmosphere within it, the shuttle’s hull morphing to an arrowhead shape. The ground had an arid, bleached look to it, dotted here and there with ruined shacks, broken domes, gutted vehicles and shot-down shuttles. There were patches of shallow-rooted, mainly dark-red tundra vegetation: cotton grass, saxifrage, arctic poppies and lichen. Clavain knew each species by its distinct infrared signature, but many of the plants were in recession now that the imported bird species had died. Ice lay in great silver swathes, and what few expanses of open water remained were warmed by buried thermopiles. Elsewhere, whole zones had reverted to almost sterile permafrost. It could have been a kind of paradise, Clavain thought, had the war not ruined everything. Yet what had happened here could only be a foretaste of the devastation that would follow across the system, on Earth as well as Mars, if another war was allowed to happen.
‘Do you see the nest yet?’ Voi said.
‘Wait a second,’ Clavain said, requesting a head-up display that boxed the nest. ‘That’s it. A nice fat thermal signature, too. Nothing else for kilometres around — nothing inhabited, anyway.’
‘Yes. I see it now.’
The Conjoiner nest lay a third of the way from the Wall’s edge, not far from the footslopes of Arsia Mons. The entire encampment was only a kilometre across, circled by a dyke piled high with regolith dust on one side. The area within the Great Wall was large enough to have an appreciable weather system: spanning enough Martian latitude for significant Coriolis effects; enough longitude for diurnal warming and cooling to cause thermal currents.
He could see the nest much more clearly now, details leaping out of the haze.
Its external layout was crushingly familiar. Clavain’s side had been studying the nest from the vantage point of Deimos ever since the ceasefire. Phobos, with its lower orbit, would have been even better, of course — but there was no helping that, and perhaps the Phobos problem might actually prove useful in his negotiations with Galiana. She was somewhere in the nest, he knew: somewhere beneath the twenty varyingly sized domes emplaced within the rim, linked together by pressurised tunnels or merged at their boundaries like soap bubbles. The nest extended several tens of levels beneath the Martian surface; maybe deeper.
‘How many people do you think are inside?’ Voi said.
‘Nine hundred or so,’ said Clavain. ‘That’s an estimate based on my experiences as a prisoner, and the hundred or so who’ve died trying to escape since. The rest, I have to say, is pretty much guesswork.’
‘Our estimates aren’t dissimilar. A thousand or less here, and perhaps another three or four spread across the system in smaller nests. I know your side thinks we have better intelligence than that, but it happens not to be the case.’
‘Actually, I believe you.’ The shuttle’s airframe was flexing around them, morphing to a low-altitude profile with wide, bat-like wings. ‘I was just hoping you might have some clue as to why Galiana keeps wasting valuable lives on pointless escape attempts.’
Voi shrugged. ‘Maybe to her the lives aren’t anywhere near as valuable as you’d like to think.’
