World Engine

by Stephen Baxter

  Once the crew were loaded aboard and the Charon had smoothly lifted, the approach was cautious; it would take twenty-four hours for the Charon to spiral slowly down through the tenuous envelope of interstellar hydrogen that was all the atmosphere this giant world had. Malenfant had plenty of time to be shown the lander’s various systems.

  But there was indeed one heck of a view through those big blister viewports, Malenfant quickly found. All four of the crew of the Charon, plump in their pressure suits, spent much of the descent gazing out, with pilot Lighthill and co-pilot Briggs having the grandest view of all, behind their own big bubble of a window.

  The moon Melinoe orbited four diameters out from Persephone, so from the start the great planet looked the size of a dinner plate held at arm’s length, Malenfant supposed. A bowl of geography. And it was a startlingly Earthlike world – if an Earth in deep freeze – with sprawling continents, including one tremendous ribbon along the equator, and flat plains that might have been frozen oceans. Surface ice gleamed, here and there, in the starlike light of the Sun.

  Deirdra said slowly, ‘Stavros Gershon. He claims that in his time – this is a couple of centuries ago – an explorer, like himself, in a ship like his, came out this way. Tried to be the first to reach Persephone, to land there. I don’t suppose you found her.’

  Lighthill looked grave. ‘Sorry, old girl. As Briggs said we have only skimmed the surface. But I think we’d have spotted any such craft. Well – unless it was submerged in some ocean of ice, or a drift of nitrogen snow . . . Lost, I’m afraid. It is a big world.’

  Deirdra nodded. ‘I’ll relay that back to Gershon.’

  ‘And I will note the explorer’s precedence in my log, if you’d be kind enough to supply the details.’

  ‘Here.’ Guy Briggs handed out sheets of paper with what turned out to be a Mercator-projection map of the world below. It was quite well drawn, but the copies were all heavily marked up by hand corrections.

  ‘Might help you get oriented,’ Briggs said. ‘The bods at the Royal Geographical Society in London drew this up, which is why it looks so pretty. They supplied most of the names of the features too, in conjunction with the astronomers. They even deigned to consult some of us who had actually been out here. Good of them, what? But you can see we’re making supplemental discoveries all the time.’

  Nicola looked over at Malenfant. ‘I’ve seen this before, in training. Tell me what you make of it, Malenfant.’

  He studied the image. ‘Looks like five major continents. Including that long linear landmass that seems to pretty much follow the equator. Slightly odd distribution? I’m no geologist. And these asterisks, marked along the equator—’

  ‘The Towers,’ Briggs said. ‘The markings are indicative only. There are sixty-five thousand of them, right around the planet. Too crowded to show individually, not at this scale. And, yes, they do follow the equator, Malenfant.’

  ‘All right. The major features – four other irregular land masses, two to the north of the equatorial ribbon, two to the south.’ He squinted to read the map. ‘Going anti-clockwise from the north-west: Jubecca, Ptolemea, Antenora, Caina. Where the hell did you get those names?’

  Briggs laughed. ‘From hell, actually, Malenfant. Don’t you know your Dante? These are the divisions of the ninth circle of hell, in the Inferno. Respectively the chambers of the betrayers of benefactors, guests, country and kin. At a certain class of school one does rather get such stuff beaten into one.’

  ‘How exactly did you guys acquire an empire? . . . But I guess it’s appropriate for Persephone, queen of hell. That upper right continent looks – odd.’ The map showed a nest of concentric contour lines. ‘Like one huge mountain.’

  ‘That’s pretty much it,’ Briggs said. ‘It’s a shield volcano – where you have a huge plume of mantle material pushing, pushing from beneath. Like Hawaii on Earth, or Mount Kitchener on Mars.’

  Malenfant suppressed a grin. So in the British reality Mons Olympus had been named after the jonbar hinge, then. ‘And the central linear feature—’

  ‘Iscariot,’ Briggs said. ‘The betrayer of Jesus, cast down into the pit of hell. The ultimate naughty step.’

  ‘And beneath the midline of the equatorial continent – south of Iscariot – a lot of fragmented land . . . islands. An archipelago?’

  ‘We called that Malebolge,’ Briggs said.

  Malenfant rehearsed the pronunciation in his head. Mal-lay-bol-gay.

  ‘For the eighth circle of hell, where, immersed in a pool of pitch, you would find hypocrites, thieves and corrupt politicians.’

  ‘I see you put your zero meridian here, right through the middle of the archipelago. Why?’

  ‘That was the biologists’ suggestion,’ Nicola said. ‘At one of the conferences that drew up the names for the features. If this planet had been left alone, close to the Sun, that archipelago in particular would have been an ideal locus for the emergence of a civilisation. Like ancient Greece, all those islands within easy ocean transport. Cultural laboratories. So agreed the bods in London, who may have been a bit too influenced by their classical educations. Anyhow that’s why we put the meridian there.’

  ‘Hmm. A gesture to what might have been. OK.’ He stared at the map, trying to tease out more clues. This by a man who never even reached orbit around his home planet before his coldsleep, he reminded himself. ‘This place looks more geologically active than Earth.’

  ‘True,’ said Nicola. ‘Simply because it’s that much bigger. It will retain its heat better, has more of a primordial load of natural radioactive isotopes in its interior . . . Being displaced to the comet cloud won’t have made much difference to that, by the way. Air freezes; water freezes; geology doesn’t stop.

  ‘So there will have been continental drift, mountain-building events, out here in the dark with no eyes to see. Some differences, of course. On Earth the air and water erode away the mountains. Not here. And it’s thought that Earth’s liquid water, getting dragged down into the mantle when continental plates bump up against each other, helps to lubricate the tectonic processes, in a way. Here, much of the water will have been frozen out, you see. So exactly how this big geological machine has churned away out here will have been different in detail from how it would have been in the inner Solar System, but . . .’

  ‘OK.’ He looked out of his window. ‘Well, right now I think I see what looks like a major ongoing volcanic event. In the strait to the south between Jubecca and Iscariot . . .’ About nine o’clock on the clock-face of Malenfant’s map. A subdued, hellish glow.

  ‘So it is,’ Nicola confirmed. ‘Lots of mountain-building going on just there, as Jubecca is both continental-drifting down from the north and crashing into the big carcass of Iscariot.’

  ‘But meanwhile,’ Briggs reported, ‘Josh has been telling us gleefully that in the south, Ptolemea and Antenora are drifting away from Iscariot.’

  ‘Lots of sea-floor spreading there,’ Nicola said. ‘And lots of island-making. Like Iceland in the Atlantic, Malenfant.’

  ‘Ah. Hence the archipelago.’

  ‘There’s no feature quite like Malebolge on Earth. It’s not a drowned continental plate, it’s a whole puzzle-box of rifts and fractures and colliding plate fragments.’

  ‘Big planet geography.’

  ‘Correct.’

  ‘But no big impact craters?’

  ‘Well, impactors are a lot scarcer out here,’ Briggs called back. ‘There are some spectacular craters down there, if you look for them – they tend not to be eroded away as on Earth, you see.’

  ‘But no dinosaurs to kill.’

  ‘No. But there could have been, Malenfant,’ Nicola said wistfully. ‘If it hadn’t been hurled away from the Sun, this would have been a world full of life, probably. More so than Earth. And on these isolated island continents you might have got whole strands of evolution running in parallel. Dinosaurs alongside the mammals, Malenfant, just waiting for a Captain Cook or a Darwin
. Imagine that! Instead there are just anaerobic bugs – oxygen-hating – clinging on in the deepest oceans, where there are mineral vents and where a few remnant puddles of liquid water have survived under miles of ice. Some life infests the upper layers, quite similar to what we found on Melinoe. Bugs, locked in the ice. So, no dinosaurs.’

  Malenfant frowned. ‘Josh told me that the Melinoe bugs—’

  ‘Well, they aren’t really bugs—’

  ‘Had some commonalities with Earth life, our kind of life. As well as with Persephone life.’

  ‘Good old Josh gets carried away sometimes. But – commonalities down at the biochemical level, yes, it does seem so. Same amino acids, I believe.’

  ‘Josh also suggested that all these worlds might have been seeded by some common agent,’ he said heavily, ‘natural or otherwise.’ But he didn’t mention Karla and her speculations, of whom these British could have no knowledge.

  ‘Well, that’s possible, frankly, Malenfant,’ Nicola said. ‘The young Solar System was a violent place, and an unstable one, with the planets not even fixed in their orbits – clearly that was so, since Persephone somehow got expelled. You could easily have biochemical suites being carried to a number of worlds by meteorites and planetesimals – the building blocks of the planets – or even forming on one world, and being blasted off by secondary impacts and ending up on another.’

  ‘Or,’ Malenfant said, feeling reckless, ‘maybe some giant walked among the new worlds, scattering seeds.’

  Briggs barked laughter. ‘That’s quite a turn of phrase you have there, fellow.’

  ‘Yeah, well, maybe I went to a school where it didn’t get beaten out of me in favour of Dante.’

  ‘But,’ Nicola said now, ‘however Persephone got out here somebody did build those Towers, Guy. So we know there has been intelligent modification on some level.’

  Lighthill grunted. ‘That’s an appropriate moment for me to remind you all to buckle up tight. Time for a preliminary burn as we begin the final descent . . . We will come down in the local morning to give us maximum light.’

  Malenfant checked his own harness. ‘So where exactly?’

  Nicola looked over her shoulder at him and grinned. ‘On a planet full of geological and biological marvels? We are going down right where you would want to land, Malenfant.

  ‘At the foot of a Tower.’

  64

  The British were as businesslike and efficient as usual. A mere hour after the landing the crew was ordered to close up their suits, and the cabin decompressed.

  And Malenfant clambered down from the lander, Armstrong-style.

  He planted his booted foot on hard ground – featureless rock, it seemed, a dull rusty brown, littered here and there with what looked like slicks of even harder ice. His fifth world, he supposed, after Earth and the Moon, and if you counted Phobos and Melinoe. He muttered, ‘Not a bad record you’re racking up for a truck driver, Malenfant.’

  Nicola was waiting for him at the bottom of the ladder. ‘Oh, I think you were always more than that, Malenfant.’

  ‘So were you, Nicola. So were you, in another life.’

  Once the four of them were safely out – Malenfant, Nicola, Lighthill and Briggs – Lighthill had them gather in a circle, facing each other, in pressure suits made additionally heavy thanks to this world’s tougher gravity. Faces behind visors illuminated by soft interior lamps.

  Lighthill said, ‘So this is a new world for all save Guy – new to me too. Let’s just take a moment to acclimatise. Get used to the conditions. Guy?’

  ‘Beginning with the gravity,’ Briggs said. ‘Over a quarter more than Earth’s. It might not feel much at first.’

  Nicola grunted. ‘My pressure suit feels like a suit of armour.’

  ‘There is that. The big heavy boots are a pain, aren’t they?’ Briggs lifted his own feet to demonstrate the fact. ‘As I said, the increased weight may not seem like much of a drama. We have all endured much higher accelerations during spaceflight. What you’ll find, though, is that this steady, relentless pull will wear you down, somewhat. You’ll tire sooner. Your muscles will burn up that much more energy – well, in just keeping you and your suit upright, let alone walking about or doing any useful work. So be aware of that and give yourselves a break . . . And speaking of breaks.’

  He took a geological hammer from a loop at his waist, held it out, and dropped it. It did seem to fall faster than Malenfant’s gut would have predicted. Not dramatically so, but quicker.

  ‘So it falls a yard in four-tenths of a second instead of five-tenths. Enough to measure, not enough to inconvenience you, you might think. But, look.’

  He bent stiffly in his suit to pick up the hammer, and Malenfant saw that it had landed in a slick of hard-frozen water ice, and had cracked the stuff, creating a tiny, shallow crater.

  ‘The impact when a hammer falls depends on its kinetic energy. And, my friends, for a given object falling a given distance, that is thirty per cent higher here than on Earth. So if you smash a faceplate or crack a shin bone because you didn’t take this big beefy world seriously, don’t come crying to me.’

  Lighthill nodded. ‘All right, Guy. Well said, and I think we get the message. So let’s take a look at where we are, shall we?’

  They broke, dispersed. Malenfant watched his companions as they moved cautiously about, upright in their suits, evidently balancing carefully in the higher gravity, casting long, sharp shadows in the dim sunlight of a Persephone morning. The light was eerie, Malenfant thought, as if cast by a single spot onto some vast stage set.

  The ground around Malenfant, as far as he could see in the lights of the lander, was more or less flat, featureless, all the way to a sharp horizon, dark against the star-littered sky. That Mars-like rusty rock surface was crumpled here and there as if eroded by ancient geology. In places he saw what looked like splashes of dust and rubble, metres across – and, when he looked back at Charon, he saw a similar pattern sprawled across the surface beneath the landing legs of the squat craft. Landing scars: human-made features. Which made sense given the landscape; for your landing zone you would naturally choose a plain, away from hills or pits or craters, away from geologically active areas such as the volcano provinces he had glimpsed during the descent. And, once such a landing place was found, you would keep on coming back.

  Nicola stomped her way across to him.

  It struck him that this was the first time he had seen her walk under a strong gravity – and she walked heavily but easily, steadily. With no trace of that persistent limp his Nicola had suffered since her childhood accident. He recalled the similarly even gait of the Retrieved copy back on Earth, and his heart broke a little, once again.

  ‘Malenfant? Are you OK?’

  ‘Yeah. Sorry. Just a little disoriented.’

  ‘Me too. But you ain’t seen nothing yet.’ And she pointed over his shoulder.

  He turned around. And saw the Tower.

  Lighthill had brought the Charon down a good kilometre away from the Tower itself. Now, obeying a safety-first mission protocol, Lighthill himself stayed behind at the lander, while Briggs led Malenfant and Nicola to the structure itself.

  From this distance, as Malenfant walked, the Tower was just a white stripe against the sky, narrow, featureless, dead straight – dead vertical – and shining in the pinpoint sunlight. Malenfant was oddly reminded of searchlights over war-torn Baghdad – or, given he was with these British, of old movie images of wartime London, beams bright in the smoke-filled air, seeking Luftwaffe bombers. But that was another London, found by following a different Road than that from which Briggs and the others had travelled, and Malenfant supposed that the reference would have made no sense to his companions at all.

  And, still most of a kilometre out, even when he tipped his head right back, bending inside the stiff suit, he could not see the top of the structure. The Tower was a stripe of light that narrowed to invisibility before his eye found any terminus.


  Twenty kilometres tall, he thought. Twelve, thirteen miles. And evidently a built thing. On twenty-fifth-century Earth the tallest buildings humans had ever built – judging anyhow from his memories of his own era, and the evidence of the Pylons – had been skyscrapers less than a kilometre tall. And that on a world with a gentler gravity than this. Such structures would have looked like mere buttresses if placed alongside this monument. Indeed, this single Tower would have dwarfed Earth’s tallest natural structures too. Everest was only, what, eight kilometres high? Why, he had known people who had spent their whole careers as aviators who never flew as high as that Tower was reaching.

  He remembered his very first glimpse of the Towers, when Karla, the Planetary AI on the Moon, had shown him astronomical photographs of a world with an enigmatic line scratched around its equator. Towers that were visible from space, from astronomical units away. Now he was here. He laughed, softly.

  Nicola glanced at him. ‘You still OK, Malenfant?’

  ‘Yeah. Just trying to get my head around what I’m seeing . . .’

  And, what was worse in terms of a challenge to his imagination, the Tower wasn’t alone.

  The Charon had come down a kilometre or so north of the line of Towers, which were themselves spaced less than a kilometre apart, in their tremendous march around the equator. So now, as he walked forward, as he looked to left and right, he saw more Towers, cousins of the one he was aiming for, and identical in every respect, as far as he could see to either side. More sunlit stripes reaching up to the sky, the further ones soon becoming too dim to make out clearly, their tops dwindling into the starlit dark. It was like approaching some tremendous fence, he thought, a fence that stretched right around this huge planet. Visually it was a little like a view he had once had of a huge offshore wind farm in the Gulf of Mexico. The same sense of a row of evidently artificial giant structures that challenged the scale of the landscape. But the scale here was far greater, of course.