Gingerly, dragging his cable, Poole made his way past Gibson to the edge of the ‘cliff’. It was dead straight, stretching from left to right – or rather north to south, he thought, taking his bearings from the Sun. ‘This edge is razor-sharp. It looks more like a quarry than any natural feature. An open-air mine. But—’
But when he looked, cautiously, over the edge, he saw no bottom to this ‘quarry’, nothing but shadow. And, looking ahead, he saw a sharp horizon, far away. But he was looking down on that distant edge, tilting his head.
He had a sudden, terrifying sense of falling. ‘Lethe.’ He stumbled backwards, clumsy in his suit.
‘Hey.’ Nicola was first to grab him, to steady him. ‘Take it easy.’
Gibson was here now. ‘I’m sorry. Should I have warned you?’
‘Well, you showed us from above, but from down here – it’s like the ground has been sliced off. What is this, Mitch?’
‘A shaft,’ Gibson said. ‘Cut in the ground. Walls smooth to within the tolerance we can measure, and coated with some kind of – material – that we can’t make any sense of. And the depth, well, we can’t measure that either. Far beyond any depth where such a shaft ought to collapse in on itself.’
‘And how wide? From space, the scale fooled me.’
‘A hundred kilometres on a side, Michael. Near enough. And it’s regular – a perfect square. When you look at it from space it doesn’t look so odd, just a big hole in the ground. But down here – Michael, Mercury’s horizon is only three kilometres away. The far side of this shaft is so far away that you’re looking down to see it, by a degree or two, below the local horizontal. This is a well so big it cuts through the planet’s curvature.’
‘Enough. I get it. Show me how this thing was made.’
Mitch Gibson nodded. ‘Time for a Virtual show. We got good records of the event, from orbit, even from down here. Don’t be alarmed. Nothing is real . . .’
He clapped his hands.
The lip in the ground vanished. Suddenly the land was whole again, with a regular, if lumpy, horizon.
And a black sycamore seed hovered above the Mercury ground.
Nicola glared up defiantly. ‘Our buddy from Jupiter.’
‘This is what we saw,’ said Mitch Gibson.
‘We watched it coming, of course. Updates from Spaceguard, long before it got here. And it brought with it a swarm of the objects you called raindrops, the silvery spheroid forms. We lost track of those. And we did a lot of screening, but we didn’t detect any of your quagma phantoms. Even so we kept our GUTships away from the area. ’
Poole glanced at him. ‘Larunda itself runs on GUT plant.’
‘Yes. We actually made a partial evacuation, and ran down the power levels. Turned out not to be necessary . . . I think we expected the sycamore seed to make for the Sun Probe, our wormhole. Maybe it had come from one wormhole in search of another, we thought. No, it came straight here. Just about the geometric centre of the Caloris basin. Hovered in position for around an Earth day. And then it did this.’ He clapped his hands again.
The sycamore seed began to rise, smooth, silent, without creating so much as a flurry in the dust. No exhaust, Poole realised, as a GUTship’s thruster would have kicked up – as observed before, it seemed not to use any kind of reaction drive, a rocket, at all. And as the craft rose into the sunlight it remained perfectly black, featureless.
He remarked, ‘I haven’t seen it in such strong sunlight before. Where the light hits its hull – the casing, whatever – no reflection.’
Gibson nodded. ‘The light conditions were different, of course, from this simulation. But that’s an authentic detail. No reflection; perfect absorption as far as we could tell.’ He took their arms. ‘You might want to stand back from the edge. We can’t be harmed, of course, but the visuals coming up are impressive.’
Nicola, like Poole, allowed herself to be drawn back. ‘The visuals of what?’
‘The geologists say that this basin, Caloris, was created in the early days of the Solar System. Mercury itself was barely formed, when – wham! The impactor struck. We guessed it was just another planetesimal, a planetary-formation fragment, or maybe even a comet, around a hundred kilometres across. There were plenty of objects that size roaming around the young System . . . Well, we got the mass right, but that was all.’
The ground shook now, visibly. Poole looked down to see dust rising up around his feet, only to fall back quickly in the absence of any air to suspend it. And where the rocky ground was exposed, near the cliff edge, a swarm of cracks ran across the surface. Poole’s stomach clenched, and he felt profoundly uncomfortable, even though – or perhaps because – the visual effects, of this apparent tremor, did not translate into actual motion under his feet.
But he was missing the main action.
‘Look,’ Nicola murmured. ‘Michael. Look.’
He lifted his head.
The ground ahead seemed to be exploding – literally, as if implanted bombs were going up, smashing the bedrock to rubble and dust and hurling it high into space. Tilting back his head, Poole saw a kind of fountain of the debris, rising straight up, some of it even slamming into the base of the sycamore seed itself, which still climbed steadily.
All this in an eerie, airless silence.
‘We watched from Larunda. From up there it looked as if somebody had pricked Mercury with a pin, and its innards were just gushing out, a fountain . . .’ Gibson was shouting now, as if unconsciously trying to make himself heard above the non-existent noise. ‘Most of the debris was hurled upwards with such violence that it reached escape velocity, and just dispersed in space. And then—’
A shadow washed across Poole, blocking out the Sun. Even as the rock and grit and gravel continued to fountain out, something else was rising from the ground now, vast, vertical. A smooth wall of what looked like milky-white glass.
‘It’s like a building,’ Nicola murmured. ‘A huge building. Just rising up out of the ground, like it’s on some giant elevator platform.’
Gibson nodded. ‘Exactly that. But bigger than any building we ever constructed before the arcologies on Mars. It’s a cube, in fact, a hundred kilometres on a side – and as massive as if it is one vast block of water ice. Gravimeters told us that. Walled with the same stuff as the shaft it left behind – well, we think so; it gives us the same kind of reflectance signature. Nicola, Michael, behold the Caloris impactor.’
‘Lethe,’ Poole said. ‘This is what slammed into Mercury five billion years ago. And all that time it’s been down there. Waiting to be – summoned.’ And he looked up, at the sycamore seed that still rose smoothly up above the great slab, as if evoking this vast structure into existence. ‘It must have known this thing was here. The sycamore seed. It must have expected to find this.’
‘Keep watching.’
Now the whole of the object had emerged from the pit, Poole saw; he glimpsed the Mercury plain under the sharp lower edge. The tremendous cube was suspended in space, invisibly supported, it seemed, by the rising sycamore seed.
‘The two objects – the sycamore seed, this big cube – spent another day, roughly, in Mercury orbit. And then they made for the Sun. Everybody watched them go. The whole crew on Larunda, I mean. Under strict instructions not to talk to anyone from outside the station, until ordered.
‘The scientists will tell you that all we can say for certain is that the two objects flew in a kind of formation. You ask me, I think the sycamore seed towed the Cache.’
‘Cache?’
‘We had to call it something . . . And once they got there—’
‘Turn it off,’ Nicola said now, tightly. ‘Enough. Consider me overwhelmed. Let’s get back to the flitter. Turn it off!’
15
The three of them huddled in the flitter cabin, windows opaqued, coffee mugs in their hands. Mitch Gib
son had produced silver survival blankets that they draped over their shoulders.
Survival blankets, in the middle of a morning on Mercury. They had created a little human nest, Poole thought. Aside from the gravity, they could have been anywhere. They had made no contact with the rest of mankind since getting back to the flitter, save for Mitch making a routine status report back to Larunda. It was as if they had needed to escape, for a while.
‘So,’ Gibson said at length, ‘there you have it. The sycamore seed came to Mercury, and snake-charmed that structure out of the ground.’
‘Where are they now?’ Nicola asked. ‘You said they headed for the Sun.’
Gibson tapped his data slates. ‘The Cache seems to have landed on the Sun . . . I know that makes no sense. It’s sitting on the photosphere anyhow, on the visible surface. Latest update is it’s still there. Growing.’
Poole couldn’t take that in. ‘Growing? Never mind.’
Nicola asked, ‘And the sycamore seed?’
‘I told Michael. It dived into the Sun.’
Poole shook his head. ‘Some kind of suicide dive?’
Nicola snorted. ‘I hardly think so. We just don’t understand, is the truth. The what, the why, or the how of it.’
Gibson looked at them uncertainly. ‘We still have some puzzles left here. At Mercury, I mean. As I said, most of the debris thrown up when the Cache emerged was lost in space, but we sent a couple of probes flying through the cloud before it dispersed. We found biological traces in there. Complex molecules – carbohydrates, but not like the amino-acid suite Earth life uses—’
Poole felt bombarded again. ‘Whoa, Mitch, that’s one mystery too many. Biological? How could that be?’
Nicola was less fazed, and seemed to be thinking more clearly. ‘What if the impactor – the Cache – was brought here in some kind of ship? Or dragged, as the sycamore seed seems to have dragged it back out again. And if the ship made landfall itself, or couldn’t get away – maybe there was some kind of survival.’
‘Life? How?’ Poole snapped. ‘This is Mercury. Hot enough to melt lead, remember? And this was billions of years ago.’
‘Yes,’ Gibson said cautiously, ‘but actually there is water here. As you know, Michael. Ice, at the poles, in shadowed craters. And where there’s water of any kind – we learned this from Mars – life can follow, or survive anyhow. Even if the raw sunlight is lethal, you can burrow into the ground, where there’s shelter, and thermal energy is available from volcanism, minerals. And in the shattered ground over the impactor there might have been room to grow and spread – spaces between the boulders and the dust grains. So it’s possible.
‘We may never know. If there was something surviving in the extraction zone, at the centre of the crater – after all this time – unless it spread away from the crater, which is possible, it’s lost now, blasted to space with the rock and the rubble.’
One mystery too many. Poole shrank inside himself, staring into his coffee cup, his mind churning with more or less wild speculation.
‘This has changed everything for us,’ Mitch was saying. ‘Mercury’s not a place you’re ever going to love. But it has resources. You can transfer lunar mining techniques, which we’ve perfected over centuries, straight here to work the upper regolith. Then you have that lovely iron-rich core, only a few hundred kilometres deep. And free energy from the Sun – six times the power density per unit area as at Earth. Mercury could become the workshop of the Solar System.’ He sighed. ‘Or it could have. Now we have this sycamore seed and its progeny rampaging around the inner System, and I guess everything is on hold. Maybe I ought to fix us some food.’ He folded up his blanket and went to the galley area at the rear of the little craft.
Nicola shuffled over to Poole. ‘Tell me why you’re so quiet.’
‘I’ve a lot to be quiet about.’
‘Such as?’
He glared at her. ‘Think about it. The sycamore seed came along and dragged this – Cache, whatever – out of the Mercury rock. A Cache that was implanted there five billion years ago. Since when it’s been sitting, waiting until it’s needed. How in Lethe did the sycamore seed know the Cache was there? And what caused the Cache to be put there in the first place, all that time ago, when the Solar System was forming? Is it just coincidence, that it’s there when it’s needed?’
Nicola thought that over. ‘The principle of mediocrity.’
‘The what?’
‘See, I’m not so vacuous as you think. Mediocrity. A guiding philosophical principle of science. The idea is that we shouldn’t expect to find ourselves in a special place, or a special time. We’re a typical sample of the universe. Which kind of feels right, doesn’t it? More than the alternative anyhow, the idea that we’re special, which sounds – well, grandiose. Then again I’m not a Poole, I don’t do grandiose. But, you see, if our Solar System is typical, then maybe every young planetary system gets an early visitor, and some inner planet gets whacked with one of these Caches—’
‘Just in case it’s ever needed.’ He looked at her. ‘So we’re dealing with some kind of agency that had the power to emplace these Caches in every system, across the Galaxy . . .’
‘Anyhow, all that is irrelevant.’
He had to smile. ‘Maybe this is why I’m travelling with you, Nicola. For comments like that. A Galaxy-wide superpower meddling in the formation of every stellar system, irrelevant? Compared to what?’
‘Compared to what the sycamore seed is going to do next, and how we deal with it. So it’s dived into the Sun. Why? What’s it looking for? What’s it going to do when it finds it?’
‘I don’t know.’ A knot of defiance formed, deep in Poole’s heart. ‘But that’s our Sun.’
‘That’s the spirit. Not only that, it’s your fight. Don’t look at me like that – the Wormhole Ghost went to a lot of trouble to tell you so. Now we have to figure out what to do next.’ She grinned. ‘Of course, I have an idea.’
Poole knew about her ideas. His heart thumped faster.
Mitch Gibson called over, ‘You two want salt in your mashed potato?’
‘No,’ Nicola said boldly. ‘But I do want your wormhole.’
Mitch glanced at her, back at his potatoes, over at her again. A classic double-take, Poole thought. ‘You want what?’
‘The Sun Probe. Think it would take a pilot’s couch? Mitch, you’re burning those potatoes.’
‘Oh, Lethe—’
16
It took Mitch Gibson’s Mercury-shadow hermits less than a week to rig up a crewed capsule inside the existing infrastructure of the Sun Probe. Poole wasn’t particularly surprised; the engineering of human survival was a much less novel technological feat than that of delivering a functioning scientific probe to the inner layers of the Sun in the first place. Once they’d grasped the mission, in fact, the Larunda team had enjoyed the challenge.
‘But by the time we’re done with you two,’ Gibson said with a certain relish, ‘you won’t know where your own bodies end and the probe begins.’
Poole knew he wasn’t kidding.
The basics of the design were drawn up in hasty sketches during a single coffee-fuelled night shift. An adapted flitter would sit inside a wormhole portal. A compact GUTdrive would propel the craft through the Sun’s interior. The negative-energy fields which propped open the wormhole portal would help shield the flitter from the dense plasma of the solar environment, while the wormhole itself would keep the little craft cool by the simple means of refrigeration: by pumping out solar heat through the wormhole’s higher-dimensional throat and dumping it into space in Mercury’s orbit, where the other end of the wormhole drifted amid a cloud of construction shacks and observation posts.
The new crewed compartment, built into the existing ‘Solar Module’, was to be a sphere, for structural strength. Though the sketchy mission plan was minimall
y ambitious, Gibson had insisted that the capsule be over-engineered: made capable of surviving all the way down to the edge of the Sun’s fusing core itself, where the temperature was measured in millions of degrees, and gamma and X-ray photons hammered through a high-density gas of electrons and protons.
Nicola Emry was, predictably, more interested in their new craft’s propulsion system. This would not be just a simple descent, but a powered exploration. A GUTdrive would still function inside the carcass of a star, as the Pooles’ venerable Grand Unified Theory technologies relied on a realm of physics – the unification of electromagnetic and nuclear forces – even more energetic than the hydrogen-fusion processes that powered the Sun.
Nicola had whooped as she took the modified probe, a neat sphere, for its first test flight above the plains of Mercury.
The one aspect of the Sun’s environment from which their sturdy craft would not be able to shield them was the star’s gravity, which would be as much as twenty-seven times Earth’s at the surface. Even Jupiter’s gravity, at the upper cloud layers, was only some two and a half times Earth’s; people had ventured there and returned safely, but the Sun’s challenge was ten times harder. Poole Industries had experimented with exotic-physics inertial screens, but they were inadequate for this challenge. And so more old-fashioned methods had to be used.
It took the whole of the last day before the descent to prepare the travellers for this. With the help of two young, kindly, medically trained techs, Poole, with Nicola at his side, was immersed in a thick, gel-like, oxygen-rich fluid, which would fill Poole’s lungs, his stomach, the cavities in his body. Even the fluid in the spaces in his skull, around his brain, was reinforced; even the fluid in his eyes. And, too, a network of nanotech robots crawled through his body, strengthening his muscular and skeletal structures, bracing cartilage and muscle and bone. Despite anaesthetics, he thought he could feel much of this.
Nicola, typically, blustered through it. When they endured the final lung-filling injection of support fluid, an experience that felt like nothing so much as drowning, Poole watched a monitor showing Nicola’s face, behind a thick glass plate. She opened her mouth, dragged in the fluid, coughed once, and then glared out, grinning. ‘So what’s next?’
Xeelee: Vengeance Page 9
