46 – Shuttle

   'Speaking from memory,' said Dr Anderson, 'Goddard's first rocket flew about fifty metres. I wonder if Mr Chang will beat that record?'
   'He'd better – or we'll all be in trouble.'
   Most of the science team had gathered in the observation lounge, and everyone was staring anxiously back along the hull of the ship. Although the entrance of the 'garage' was not visible from this angle, they would see the Bill Tee soon enough, when – and if – it emerged.
   There was no countdown; Chang was taking his time, making every possible check – and would fire when he felt like it. The shuttle had been stripped down to its minimum mass, and was carrying just enough propellant for one hundred seconds of flight. If everything worked, that would be ample; if it didn't, more would not only be superfluous, but dangerous.
   'Here we go,' said Chang casually.
   It was almost like a conjuring trick; everything happened so quickly that the eye was deceived. No one saw Bill Tee pop out of the garage, because it was hidden in a cloud of steam. When the cloud had cleared, the shuttle was already landing, two hundred metres away.
   A great cheer of relief echoed through the lounge.
   'He did it!' cried ex-Acting Captain Lee. 'He's broken Goddard's record – easily!'
   Standing on its four stubby legs in the bleak Europan landscape, Bill Tee looked like a larger and even less elegant version of an Apollo lunar module. That was not, however, the thought that occurred to Captain Laplace, as he looked out from the bridge. It seemed to him that his ship was rather like a stranded whale, that had managed a difficult birth in an alien element. He hoped that the new calf would survive.

   Forty-eight very busy hours later, the William Tsung was loaded, checked out on a ten-kilometre circuit over the island – and ready to go. There was still plenty of time for the mission; by the most optimistic reckoning, Universe could not arrive for another three days, and the trip to Mount Zeus, even allowing for the deployment of Dr van der Berg's extensive array of instruments, would take only six hours.
   As soon as Second Officer Chang had landed, Captain Laplace called him to his cabin. The Skipper looked, thought Chang, somewhat ill at ease.
   'Good work, Walter – but of course that's only what we expect.'
   'Thanks, Sir, So what's the problem?'
   The Captain smiled. A well-integrated crew could keep no secrets.
   'Head Office, as usual. I hate to disappoint you, but I've had orders that only Dr van der Berg and Second Officer Floyd are to make the trip.'
   'I get the picture,' Chang answered, with a trace of bitterness. 'What have you told them?'
   'Nothing, yet; that's why I wanted to talk to you. I'm quite prepared to say that you're the only pilot who can fly the mission.'
   'They'll know that's nonsense; Floyd could do the job as well as I could. There's not the slightest risk – except for a malfunction, which could happen to anyone.'
   'I'd still be willing to stick my neck out, if you insist. After all, no-one can stop me – and we'll all be heroes when we get back to Earth.'
   Chang was obviously doing some intricate calculations. He seemed rather pleased with the result.
   'Replacing a couple of hundred kilos of payload with propellant gives us an interesting new option; I'd intended to mention it earlier, but there was no way Bill Tee could manage with all that extra gear and a full crew...'
   'Don't tell me. The Great Wall.'
   'Of course; we could do a complete survey in one or two passes, and find what it really is.'
   'I thought we had a very good idea, and I'm not sure if we should go near it. That might be pressing our luck.'
   'Perhaps. But there's another reason; to some of us, it's an even better one...'
   'Go on.'
   'Tsien. It's only ten kilometres from the Wall. We'd like to drop a wreath there.'
   So that was what his officers had been discussing so solemnly; not for the first time, Captain Laplace wished he knew a little more Mandarin.
   'I understand,' he said quietly. 'I'll have to think it over – and talk to van der Berg and Floyd to see if they agree.'
   'And Head Office?'
   'No, dammit. This will be my decision.'

47 – Shards

   'You'd better hurry,' Ganymede Central had advised, 'The next conjunction will be a bad one – we'll be triggering quakes as well as Io. And we don't want to scare you – but unless our radar's gone crazy, your mountain's sunk another hundred metres since the last check.'
   At that rate, thought van der Berg, Europa will be flat again in ten years. How much faster things happened here than on Earth; which was one reason why the place was so popular with geologists.
   Now that he was strapped into the number two position immediately behind Floyd, and virtually surrounded by consoles of his own equipment, he felt a curious mixture of excitement and regret. In a few hours, the great intellectual adventure of his life would be over – one way or the other. Nothing that would ever happen again could possibly match it.
   He did not have the slightest trace of fear; his confidence in both man and machine was complete. One unexpected emotion was a wry sense of gratitude to the late Rose McCullen; without her, he would never have had this opportunity, but might have gone, still uncertain, to his grave.
   The heavily laden Bill Tee could barely manage one-tenth of a gravity at lift-off; it was not intended for this sort of work, but would manage much better on the homeward journey when it had deposited its cargo. It seemed to take ages to climb clear of Galaxy, and they had ample time to note the damage to the hull as well as signs of corrosion from the occasional mildly acid rains. While Floyd concentrated on the lift-off, van der Berg gave a quick report on the ship's condition from the viewpoint of a privileged observer. It seemed the right thing to do – even though, with any luck, Galaxy's space-worthiness would soon be of no further concern to anyone.
   Now they could see the whole of Haven spread out beneath them, and van der Berg realized what a brilliant job Acting Captain Lee had done when he beached the ship. There were only a few places where it could have been safely grounded; although a good deal of luck had also been involved, Lee had used wind and sea-anchor to the best possible advantage.
   The mists closed around them; Bill Tee was rising on a semi-ballistic trajectory to minimize drag, and there would be nothing to see except the clouds for twenty minutes. A pity, thought van der Berg; I'm sure there must be some interesting creatures swimming around down there, and no-one else may have a chance of seeing them.
   'Coming up to engine cut-off,' said Floyd. 'Everything normal.'
   'Very good, Bill Tee. No report of traffic at your altitude. You're still number one on the runway to land.'
   'Who's that joker?' asked van der Berg.
   'Ronnie Lim. Believe it or not, that "number one on the runway" goes back to Apollo.'
   Van der Berg could understand why. There was nothing like the occasional touch of humour – providing it was not overdone – to relieve the strain when men were involved in some complex and possibly hazardous enterprise.
   'Fifteen minutes before we start braking,' said Floyd. 'Let's see who else is on the air.'
   He started the autoscan, and a succession of beeps and whistles, separated by short silences as the tuner rejected them one by one in its swift climb up the radio spectrum, echoed round the little cabin.
   'Your local beacons and data transmissions,' said Floyd. 'I was hoping – ah, here we are!'
   It was only a faint musical tone, warbling rapidly up and down like a demented soprano. Floyd glanced at the frequency meter.
   'Doppler shift almost gone – she's slowing fast.'
   'What is it -text?'
   'Slowscan video, I think. They're relaying a lot of material back to Earth through the big dish on Ganymede, when it's in the right position. The networks are yelling for news.'
   They listened to the hypnotic but meaningless sound for a few minutes; then Floyd switched it off. Incomprehensible though the transmission from Universe was to their unaided senses, it conveyed the only message that mattered. Help was on the way, and would soon be there.
   Partly to fill the silence, but also because he was genuinely interested, van der Berg remarked casually: 'Have you talked to your grandfather lately?'
   'Talked', of course, was a misnomer where interplanetary distances were concerned, but no-one had come up with an acceptable alternative. 'Voicegram', 'audiomail' and 'vocard' had all flourished briefly, then vanished into limbo. Even now, most of the human race probably did not believe that realtime conversation was impossible in the Solar System's wide, open spaces, and from time to time indignant protests were heard: 'Why can't you scientists do something about it?'
   'Yes,' said Floyd. 'He's in fine shape, and I look forward to meeting him.'
   There was a slight strain in his voice. I wonder, thought van der Berg, when they last met; but he realized that it would be tactless to ask. Instead, he spent the next ten minutes rehearsing the off-loading and setting-up procedures with Floyd, so there would be no unnecessary confusion when they touched down.
   The COMMENCE BRAKING alarm went off just a fraction of a second after Floyd had already started the program sequencer. I'm in good hands, thought van der Berg: I can relax and concentrate on my job. Where's that camera – don't say it's floated away again.
   The clouds were clearing. Even though the radar had shown exactly what was beneath them, in a display as good as normal vision could provide, it was still a shock to see the face of the mountain rearing up only a few kilometres ahead.
   'Look!' cried Floyd suddenly. 'Over to the left -by that double peak – give you one guess!'
   'I'm sure you're right – I don't think we did any damage – it just splattered – wonder where the other one hit-'
   'Altitude one thousand. Which landing site? Alpha doesn't look so good from here.'
   'You're right – try Gamma – closer to the mountain, anyway.'
   'Five hundred. Gamma it is. I'll hover for twenty secs – if you don't like it, we'll switch to Beta. Four hundred... Three hundred... Two hundred. ('Good luck, Bill Tee,' said Galaxy briefly). Thanks, Ronnie... One hundred and fifty... One hundred... Fifty... How about it? Just a few small rocks, and – that's peculiar – what looks like broken glass all over the place – someone's had a wild party here... Fifty... Fifty... Still OK?'
   'Perfect. Go down.'
   'Forty... thirty... twenty... Sure you don't want to change your mind?... Ten... Kicking up a little dust, as Neil said once – or was it Buzz?... Five... Contact! Easy, wasn't it? Don't know why they bother to pay me.'

48 – Lucy

   'Hello, Gany Central – we've made a perfect landing – I mean Chris has – on a flat surface of some metamorphic rock – probably the same pseudogranite we've called Havenite. The base of the mountain is only two kilometres away, but already I can tell there's no real need to go any closer.
   'We're putting on our top-suits now, and will start unloading in five minutes. Will leave the monitors running, of course, and will call on every quarter-hour. Van out.'
   'What did you mean by that "no need to go any closer"?' asked Floyd.
   Van der Berg grinned. In the last few minutes he seemed to have shed years, and almost to have become a carefree boy.
   'Circumspice,' he said happily. 'Latin for "look around you". Let's get the big camera out first – wow!'
   The Bill Tee gave a sudden lurch, and for a moment heaved up and down on its landing-gear shock absorbers with a motion that, if it had continued for more than a few seconds, would have been a recipe for instant sea sickness.
   'Ganymede was right about those quakes,' said Floyd, when they had recovered. 'Is there any serious danger?'
   'Probably not; it's still thirty hours to conjunction, and this looks a solid slab of rock. But we won't waste any time here – luckily we won't need to. Is my mask straight? It doesn't feel right.'
   'Let me tighten the strap. That's better. Breathe in hard – good, now it fits fine. I'll go first.'
   Van der Berg wished that his could be the first small step, but Floyd was the commander and it was his duty to check that the Bill Tee was in good shape – and ready for an immediate take-off.
   He walked once around the little spacecraft, examining the landing gear, then gave the thumbs-up signal to van der Berg, who started down the ladder to join him. Although he had worn the same lightweight breathing equipment on his exploration of Haven, he felt a little awkward with it, and paused at the landing pad to make some adjustments. Then he glanced up – and saw what Floyd was doing.
   'Don't touch it!' he cried. 'It's dangerous!'
   Floyd jumped a good metre away from the shards of vitreous rock he was examining. To his untrained eye, they looked rather like an unsuccessful melt from a large glass furnace.
   'It's not radioactive, is it?' he asked anxiously. 'No. But stay away until I've got there.'
   To his surprise, Floyd realized that van der Berg was wearing heavy gloves. As a space officer, it had taken him a long time to grow accustomed to the fact that, here on Europa, it was safe to expose one's bare skin to the atmosphere. Nowhere else in the Solar System – even on Mars – was that possible.
   Very cautiously, van der Berg reached down and picked up a long splinter of the glassy material. Even in this diffused light, it glittered strangely, and Floyd could see that it had a vicious edge.
   'The sharpest knife in the known universe,' said van der Berg happily.
   'We've been through all this to find a knife!'
   Van der Berg started to laugh, then found it wasn't easy inside his mask.
   'So you still don't know what this is about?'
   'I'm beginning to feel I'm the only one who doesn't.'
   Van der Berg took his companion by the shoulder, and turned him to face the looming mass of Mount Zeus. From this distance, it filled half the sky – not merely the greatest, but the only mountain on this whole world.
   'Admire the view just for one minute. I have an important call to make.'
   He punched a code sequence on his comset, waited for the READY light to flash, and said: 'Ganymede Central 109 – this is Van. Do you receive?'
   After no more than the minimum timelag, an obviously electronic voice answered:
   'Hello, Van. This is Ganymede Central 109. Ready to receive.'
   Van der Berg paused, savouring the moment he would remember for the rest of his life.
   'Contact Earth Ident Uncle 737. Relay following message. LUCY IS HERE. LUCY IS HERE. End message. Please repeat.'
   Perhaps I should have stopped him saying that, whatever it means, thought Floyd, as Ganymede repeated the message. But it's too late now. It will reach Earth within the hour.
   'Sorry about that, Chris,' grinned van der Berg. 'I wanted to establish priority – amongst other things.'
   'Unless you start talking soon, I'll begin carving you up with one of these patent glass knives.'
   'Glass, indeed! Well, the explanation can wait – it's absolutely fascinating, but quite complicated. So I'll give you the straight facts.
   'Mount Zeus is a single diamond, approximate mass one million million tons. Or, if you prefer it that way, about two times ten to the seventeenth carats. But I can't guarantee that it's all gem quality.'

VII – THE GREAT WALL

49 – Shrine

   As they unloaded the equipment from Bill Tee and set it up on their little granite landing-pad, Chris Floyd found it hard to tear his eyes away from the mountain looming above them. A single diamond – bigger than Everest! Why, the scattered fragments lying round the shuttle must be worth billions, rather than millions.
   On the other hand, they might be worth no more than – well, scraps of broken glass. The value of diamonds had always been controlled by the dealers and producers, but if a literal gem-mountain came suddenly on the market, prices would obviously collapse completely. Now Floyd began to understand why so many interested parties had focused their attention upon Europa; the political and economic ramifications were endless.
   Now that he had at last proved his theory, van der Berg had become again the dedicated and single-minded scientist, anxious to complete his experiment with no further distraction. With Floyd's help – it was not easy to get some of the bulkier pieces of equipment out of Bill Tee's cramped cabin – they first drilled a metre-long core with a portable electric drill, and carried it carefully back to the shuttle.
   Floyd would have had a different set of priorities, but he recognized that it made sense to do the harder tasks first. Not until they had laid out a seismograph array and erected a panoramic TV camera on a low, heavy tripod did van der Berg condescend to collect some of the incomputable riches lying all around them.
   'At the very least,' he said, as he carefully selected some of the less lethal fragments, 'they'll make good souvenirs.'
   'Unless Rosie's friends murder us to get them.'
   Van der Berg looked sharply at his companion; he wondered how much Chris really knew – and how much, like all of them, he was guessing.
   'Not worth their while, now that the secret's out. In about an hour's time, the Stock Exchange computers will be going crazy.'
   'You bastard!' said Floyd, with admiration rather than rancour. 'So that's what your messsage was about.'
   'There's no law that says a scientist shouldn't make a little profit on the side – but I'm leaving the sordid details to my friends on Earth. Honestly, I'm much more interested in the job we're doing here. Let me have that wrench, please...'
   Three times before they had finished establishing Zeus Station they were almost knocked off their feet by quakes. They could feel them first as a vibration underfoot, then everything would start shaking – then there would be a horrible, long-drawn-out groaning sound that seemed to come from every direction. It was even air-borne, which to Floyd seemed strangest of all. He could not quite get used to the fact that there was enough atmosphere around them to allow short-range conversations without radio.
   Van der Berg kept assuring him that the quakes were still quite harmless, but Floyd had learned never to put too much trust in experts. True, the geologist had just been proved spectacularly right; as he looked at Bill Tee heaving on its shock-absorbers like a storm-tossed ship, he hoped that Van's luck would hold for at least a few more minutes.
   'That seems to be it,' said the scientist at last, to Floyd's great relief. 'Ganymede's getting good data on all channels. The batteries will last for years, with the solar panel to keep recharging them.'
   'If this gear is still standing a week from now, I'll be very surprised. I'll swear that mountain's moved since we landed – let's get off before it falls on top of us.'
   'I'm more worried,' laughed van der Berg, 'that your jet-blast will undo all our work.'
   'No risk of that – we're well clear, and now we've offloaded so much junk we'll need only half-power to lift. Unless you want to take aboard a few more billions. Or trillions.'
   'Let's not be greedy. Anyway, I can't even guess what this will be worth when we get it to Earth. The museums will grab most of it, of course. After that – who knows?'
   Floyd's fingers were flying over the control panel as he exchanged messages with Galaxy.
   'First stage of mission completed. Bill Tee ready for take-off. Flight plan as agreed.'
   They were not surprised when Captain Laplace answered.
   'You're quite certain you want to go ahead? Remember, you have the final decision. I'll back you up, whatever it is.'
   'Yessir, we're both happy. We understand how the crew feels. And the scientific payoff could be enormous – we're both very excited.'
   'Just a minute – we're still waiting for your report on Mount Zeus!'
   Floyd looked at van der Berg, who shrugged his shoulders and then took the microphone.
   'If we told you now, Captain, you'd think we were crazy – or pulling your leg. Please wait a couple of hours until we're back – with the evidence.'
   'Hm. Not much point giving you an order, is it? Anyway – good luck. And from the owner as well – he thinks going to Tsien is a splendid idea.'
   'I knew Sir Lawrence would approve,' Floyd remarked to his companion. 'And anyway – with Galaxy already a total loss, Bill Tee's not much extra risk, is it?'
   Van der Berg could see his point of view, even though he did not entirely subscribe to it. He had made his scientific reputation; but he still looked forward to enjoying it.
   'Oh – by the way,' Floyd said. 'Who was Lucy – anybody in particular?'
   'Not as far as I know. We came across her in a computer search, and decided the name would make a good code word – everyone would assume it was something to do with Lucifer, which is just enough of a half-truth to be beautifully misleading....
   'I'd never heard of them, but a hundred years ago there was a group of popular musicians with a very strange name – the Beatles – spelled B-E-A-T-L-E-S, don't ask me why. And they wrote a song with an equally strange title: "Lucy in the Sky with Diamonds". Weird, isn't it? Almost as if they knew...'

   According to Ganymede radar, the wreck of the Tsien lay three hundred kilometres west of Mount Zeus, towards the twilight zone and the cold lands beyond. Permanently cold they were, but not dark; half the time they were brilliantly lit by the distant Sun. However, even by the end of the long Europan solar day, the temperature was still far below freezing point. As liquid water could exist only on the hemisphere facing Lucifer, the intermediate region was a place of continual storms, where rain and hail, sleet and snow contended for supremacy.
   During the half-century since Tsien's disastrous landing, the ship had moved almost a thousand kilometres. It must have drifted – like Galaxy – for several years on the newly created Sea of Galilee, before coming to rest on its bleakly inhospitable shore.
   Floyd picked up the radar echo as soon as Bill Tee flattened out at the end of its second leap across Europa. The signal was surprisingly weak for so large an object; as soon as they broke through the clouds, they realized why.
   The wreck of the spaceship Tsien, first man-carrying vessel to land on a satellite of Jupiter, stood in the centre of a small, circular lake – obviously artificial, and connected by a canal to the sea, less than three kilometres away. Only the skeleton was left, and not even all of that; the carcass had been picked clean.
   But by what? van der Berg asked. There was no sign of life there; the place looked as if it had been deserted for years. Yet he had not the slightest doubt that something had stripped the wreck, with deliberate and indeed almost surgical precision.
   'Obviously safe to land,' said Floyd, waiting for a few seconds to get van der Berg's almost absentminded nod of approval. The geologist was already videoing everything in sight.
   Bill Tee settled down effortlessly by the side of the pool, and they looked across the cold, dark water at this monument to man's exploring impulses. There seemed no convenient way of getting to the wreck, but that did not really matter.
   When they had suited up, they carried the wreath to the water's edge, held it solemnly for a moment in front of the camera, then tossed in this tribute from Galaxy's crew. It had been beautifully made; even though the only raw materials available were metal foil, paper and plastic, one could easily believe that the flowers and leaves were real. Pinned all over them were notes and inscriptions, many written in the ancient but now officially obsolete script rather than Roman characters.
   As they were walking back to the Bill Tee, Floyd said thoughtfully: 'Did you notice – there was practically no metal left. Only glass, plastic, synthetics.'
   'What about those ribs and supporting girders?'
   'Composite – mostly carbon, boron. Someone round here is very hungry for metal – and knows it when it sees it. Interesting...'
   Very, thought van der Berg. On a world where fire could not exist, metals and alloys would be almost impossible to make, and as precious as – well, diamonds.
   When he had reported to base, and received a message of gratitude from Second Officer Chang and his colleagues, Floyd took the Bill Tee up to a thousand metres and continued westward.
   'Last lap,' he said, 'no point in going higher – we'll be there in ten minutes. But I won't land; if the Great Wall is what we think it is, I'd prefer not to. We'll do a quick flyby and head for home. Get those cameras ready; this could be even more important than Mount Zeus.'
   And, he added to himself, I may soon know what Grandfather Heywood felt, not so far from here, fifty years ago. We'll have a lot to talk about when we meet – less than a week from now, if all goes well.

50 – Open City

   What a terrible place, thought Chris Floyd – nothing but driving sleet, flurries of snow, occasional glimpses of landscapes streaked with ice – why, Haven was a tropical paradise by comparison! Yet he knew that the nightside, only a few hundred kilometres further on round the curve of Europa, was even worse.
   To his surprise, the weather cleared suddenly and completely just before they reached their goal. The clouds lifted – and there ahead was an immense, black wall, almost a kilometre high, lying directly across Bill Tee's flight path. It was so huge that it was obviously creating its own microclimate; the prevailing winds were being deflected around it, leaving a local, calm area in its lee.
   It was instantly recognizable as the Monolith, and sheltering at its foot were hundreds of hemispherical structures, gleaming a ghostly white in the rays of the low-hanging sun that had once been Jupiter. They looked, thought Floyd, exactly like old-style beehives made of snow; something in their appearance evoked other memories of Earth. Van der Berg was one jump ahead of him.
   'Igloos,' he said. 'Same problem – same solution. No other building material around here, except rock – which would be much harder to work. And the low gravity must help – some of those domes are quite large. I wonder what lives in them...'
   They were still too far away to see anything moving in the streets of this little city at the edge of the world. And as they came closer, they saw that there were no streets.
   'It's Venice, made of ice,' said Floyd. 'All igloos and canals.'
   'Amphibians,' answered van der Berg. 'We should have expected it. I wonder where they are?'
   'We may have scared them. Bill Tee's much noisier outside than in.'
   For a moment, van der Berg was too busy filming and reporting to Galaxy to reply. Then he said: 'We can't possibly leave without making some contact. You're right – this is far bigger than Mount Zeus.'
   'And it could be more dangerous.'
   'I don't see any sign of advanced technology – correction, that looks like an old twentieth-century radar dish over there! Can you get closer?'
   'And get shot at? No thanks. Besides, we're using up our hover time. Only another ten minutes – if you want to get home again.'
   'Can we at least land and look around? There's a patch of clear rock over there. Where the hell is everybody?'
   'Scared, like me. Nine minutes. I'll do one trip across town – film everything you can – yes, Galaxy – we're OK – just rather busy at the moment – call you later -'
   'I've just realized – that's not a radar dish, but something almost as interesting. It's pointing straight at Lucifer – it's a solar furnace! Makes a lot of sense in a place where the sun never moves – and you can't light a fire.'
   'Eight minutes. Too bad everyone's hiding indoors.'
   'Or back in the water. Can we look at that big building with the open space around it? I think it's the town hall.'
   Van der Berg was pointing towards a structure much larger than all the others, and of quite different design; it was a collection of vertical cylinders, like oversized organ-pipes. Moreover, it was not the featureless white of the igloos, but showed a complex mottling over its entire surface.
   'Europan art!' cried van der Berg. 'That's a mural of some kind! Closer, closer! We must get a record!'
   Obediently, Floyd dropped lower – and lower – and lower. He seemed to have completely forgotten all his earlier reservations about hover time; and suddenly, with shocked incredulity, van der Berg realized that he was going to land.
   The scientist tore his eyes from the rapidly approaching ground, and glanced at his pilot. Though he was obviously still in full control of Bill Tee, Floyd seemed to be hypnotized; he was staring at a fixed point straight ahead of the descending shuttle.
   'What's the matter, Chris?' van der Berg cried. 'Do you know what you're doing?'
   'Of course. Can't you see him?'
   'See who?'
   'That man, standing by the biggest cylinder. And he's not wearing any breathing gear!'
   'Don't be an idiot, Chris: there's no one there.'
   'He's looking up at us. He's waving – I think I recog – Oh my God!'
   'There's no-one – no-one! Pull up!'
   Floyd ignored him completely. He was absolutely calm and professional as he brought Bill Tee in to a perfect landing, and cut the motor at exactly the right instant before touchdown.
   Very thoroughly, he checked the instrument readings, and set the safety switches. Only when he had completed the landing sequence did he again look out of the observation window, with a puzzled but happy expression on his face.
   'Hello, Grandfather,' he said softly, to no-one at all that van der Berg could see.

51 – Phantom

   Even in his most horrible nightmares, Dr van der Berg had never imagined being stranded on a hostile world in a tiny space capsule, with only a madman for company. But at least Chris Floyd did not seem to be violent; perhaps he could be humoured into taking off again and flying them safely back to Galaxy...
   He was still staring at nothing, and from time to time his lips moved in silent conversation. The alien 'town' remained completely deserted, and one could almost imagine that it had been abandoned for centuries. Presently, however, van der Berg noticed some tell-tale signs of recent occupancy. Although Bill Tee's rockets had blasted away the thin layer of snow immediately around them, the remainder of the little square was still lightly powdered. It was a page torn from a book, covered with signs and hieroglyphics, some of which he could read.
   A heavy object had been dragged in that direction – or had made its way clumsily under its own power. Leading from the now closed entrance of one igloo was the unmistakable track of a wheeled vehicle. Too far away to make out details was a small object that could have been a discarded container; perhaps Europans were sometimes as careless as humans...

   The presence of life was unmistakable, overwhelming. Van der Berg felt he was being watched by a thousand eyes – or other senses – and there was no way of guessing whether the minds behind them were friendly, or hostile. They might even be indifferent, merely waiting for the intruders to go away, so that they could continue their interrupted and mysterious business.
   Then Chris Floyd spoke once again into the empty air.
   'Goodbye, Grandfather,' he said quietly, with just a trace of sadness. Turning towards van der Berg he added in a normal conversational tone: 'He says it's time to leave. I guess you must think I'm crazy.'
   It was wisest, decided van der Berg, not to agree. In any event, he soon had something else to worry about.
   Floyd was now staring anxiously at the read-outs that Bill Tee's computer was feeding to him. Presently he said, in an understandable tone of apology:
   'Sorry about this, Van. That landing used up more fuel than I'd intended. We'll have to change the mission profile.'
   That, van der Berg thought bleakly, was a rather roundabout way of saying: 'We can't get back to Galaxy.' With difficulty, he. managed to suppress a 'Damn your grandfather!' and merely asked: 'So what do we do?'
   Floyd was studying the chart, and punching in more numbers.
   'We can't stay here -, (Why not? thought van der Berg. If we're going to die anyway, we might use our time learning as much as possible.) ' – so we should find a place where the shuttle from Universe can pick us up easily.'
   Van der Berg breathed a huge mental sigh of relief. Stupid of him not to have thought of that; he felt like a man who had been reprieved just when he was being taken to the gallows. Universe should reach Europa in less than four days; Bill Tee's accommodation could hardly be called luxurious, but it was infinitely preferable to most of the alternatives he could imagine.
   'Away from this filthy weather – a stable, flat surface – closer to Galaxy, though I'm not sure if that helps much – shouldn't be any problem. We've enough for five hundred kilometres – it's just that we can't risk the sea crossing.'
   For a moment, van der Berg thought wistfully of Mount Zeus; there was so much that could be done there. But the seismic disturbances – steadily getting worse as lo came into line with Lucifer – ruled that out completely. He wondered if his instruments were still working, and would check them again as soon as they'd dealt with the immediate problem.
   'I'll fly down the coast to the equator – best place to be anyway for a shuttle landing – the radar map showed some smooth areas just inland round sixty west.'
   'I know. The Masada Plateau.' (And, van der Berg added to himself, perhaps a chance for a little more exploring. Never miss an unexpected opportunity...)
   'The Plateau it is. Goodbye, Venice. Goodbye, Grandfather...'

   * * *

   When the muted roar of the braking rockets had died away, Chris Floyd safetied the firing circuits for the last time, released his seat belt, and stretched arms and legs as far as he could in Bill Tee's confined quarters.
   'Not such a bad view – for Europa,' he said cheerfully. 'Now we've four days to find out if shuttle rations are as bad as they claim. So – which of us starts talking first?'

52 – On the Couch

   I wish I'd studied some psychology, thought van der Berg; then I could explore the parameters of his delusion. Yet now he seems completely sane – except on that one subject.

   Though almost any seat was comfortable at one-sixth of a gravity, Floyd had tilted his to the fully reclining position and had clasped his hands behind his head. Van der Berg suddenly recalled that this was the classic position of a patient, in the days of the old and still not entirely discredited Freudian analysis.
   He was glad to let the other talk first, partly out of sheer curiosity but chiefly because he hoped that the sooner Floyd got this nonsense out of his system, the sooner he would be cured – or, at least, harmless. But he did not feel too optimistic: there must have been some serious, deep-seated problem in the first place to trigger so powerful an illusion.
   It was very disconcerting to find that Floyd agreed with him completely, and had already made his own diagnosis.
   'My crew psych rating is Al plus,' he said, 'which means that they'll even let me look at my own files – only about ten per cent can do this. So I'm as baffled as you are – but I saw Grandfather, and he spoke to me. I've never believed in ghosts – who does? – but this must mean that he's dead. I wish I could have got to know him better – I'd been looking forward to our meeting... Still, now I have something to remember...'
   Presently van der Berg asked: 'Tell me exactly what he said.'
   Chris smiled a little wanly and answered: 'I've never had one of those total recall memories, and I was so stunned by the whole thing that I can't give you many of the actual words.' He paused, and a look of concentration appeared on his face.
   'That's strange; now I look back, I don't think we did use words.'
   Even worse, thought van der Berg; telepathy as well as survival after death. But he merely said:
   'Well, give me the general gist of the – er -conversation. I never heard you say anything remember.'
   'Right. He said something like, "I wanted to see you again, and I'm very happy. I'm sure everything is going to work out well, and Universe will soon pick you up."
   Typical bland spirit message, thought van der Berg. They never say anything useful or surprising – merely reflect the hopes and fears of the listener. Zero-information echoes from the subconscious.
   'Go on.'
   'Then I asked him where everyone was – why the place was deserted. He laughed and gave me an answer I still don't understand. Something like: "I know you didn't intend any harm – when we saw you coming, we barely had time to give the warning. All the – " and here he used a word I couldn't pronounce even if I could remember it – "got into the water – they can move quite quickly when they have to! They won't come out until you've left, and the wind has blown the poison away." What could he have meant by that? Our exhaust is nice, clean steam – and that's what most of their atmosphere is, anyway.'
   Well, thought van der Berg, I suppose there's no law that says a delusion – any more than a dream – has to make logical sense. Perhaps the concept of 'poison' symbolizes some deep-rooted fear that Chris, despite his excellent psych rating, is unable to face. Whatever it is, I doubt if it's any concern of mine. Poison, indeed! Bill Tee's propellant mass is pure, distilled water shipped up to orbit from Ganymede.
   But wait a minute. How hot is it when it comes out of the exhaust? Haven't I read somewhere... ?
   'Chris,' said van der Berg cautiously, 'after the water's gone through the reactor, does it all come out as steam?'
   'What else could it do? Oh, if we run really hot, ten or fifteen per cent gets cracked to hydrogen and oxygen.'
   Oxygen! Van der Berg felt a sudden chill, even though the shuttle was at comfortable room temperature. It was most unlikely that Floyd understood the implications of what he had just said; the knowledge was outside his normal sphere of expertise.
   'Did you know, Chris, that to primitive organisms on Earth, and certainly to creatures living in an atmosphere like Europa's, oxygen is a deadly poison?'
   'You're joking.'
   'I'm not: it's even poisonous to us, at high pressure.'
   'I did know that; we were taught it in our diving course.'
   'Your – grandfather – was talking sense. It's as if we'd sprayed that city with mustard gas. Well, not quite as bad as that – it would disperse very quickly.'
   'So now you believe me.'
   'I never said I didn't.'
   'You would have been crazy if you did!'
   That broke the tension, and they had a good laugh together.
   'You never told me what he was wearing.'
   'An old-fashioned dressing gown, just as I remembered when I was a boy. Looked very comfortable.'
   'Any other details?'
   'Now you mention it, he looked much younger, and had more hair than when I saw him last. So I don't think he was – what can I say? – real. Something like a computer-generated image. Or a synthetic hologram.'
   'The Monolith!'
   'Yes – that's what I thought. You remember how Dave Bowman appeared to Grandfather on Discovery? Perhaps it's his turn now. But why? He didn't give me any warning – not even any particular message. Just wanted to say goodbye and wish me well...'
   For a few embarrassing moments Floyd's face began to crumple; then he regained control, and smiled at van der Berg.
   'I've done enough talking. Now it's your turn to explain just what a million-million-ton diamond is doing – on a world made mostly of ice and sulphur. It had better be good.'
   'It is,' said Dr Rolf van der Berg.

53 – Pressure Cooker

   'When I was studying at Flagstaff,' began van der Berg, 'I came across an old astronomy book that said: "The Solar System consists of the Sun, Jupiter – and assorted debris." Puts Earth in its place, doesn't it? And hardly fair to Saturn, Uranus and Neptune – the other three gas giants come to almost half as much as Jupiter.
   'But I'd better start with Europa. As you know, it was flat ice before Lucifer started warming it up – greatest elevation only a couple of hundred metres – and it wasn't much different after the ice had melted and a lot of the water had migrated and frozen out on Farside. From 2015 – when our detailed observations began – until '38, there was only one high point on the whole moon – and we know what that was.'
   'We certainly do. But even though I've seen it with my own eyes, I still can't picture the Monolith as a wall! I always visualize it as standing upright – or floating freely in space.'
   'I think we've learned that it can do anything it wants to – anything we can imagine – and a lot more.
   'Well, something happened to Europa in '37, between one observation and the next. Mount Zeus – all of ten kilometres high! – suddenly appeared.
   'Volcanoes that big don't pop up in a couple of weeks; besides, Europa's nothing like as active as Io.'
   'It's active enough for me,' Floyd grumbled. 'Did you feel that one?'
   'Besides, if it had been a volcano, it would have spewed enormous amounts of gas into the atmosphere; there were some changes, but nothing like enough to account for that explanation. It was all a complete mystery, and because we were scared of getting too close – and were busy on our own projects – we didn't do much except spin fantastic theories. None of them, as it turned out, as fantastic as the truth.
   'I first suspected it from some chance observations in '57, but didn't really take them seriously for a couple of years. Then the evidence became stronger; for anything less bizarre, it would have been completely convincing.
   'But before I could believe that Mount Zeus was made of diamond, I had to find an explanation. To a good scientist – and I think I'm a good one – no fact is really respectable until there's a theory to account for it. The theory may turn out to be wrong – it usually is, in some details at least – but it must provide a working hypothesis.
   'And as you pointed out, a million-million-ton diamond on a world of ice and sulphur takes a little explaining. Of course, now it's perfectly obvious and I feel a damn fool not to have seen the answer years ago. Might have saved a lot of trouble – and at least one life – if I had.'
   He paused thoughtfully, then suddenly asked Floyd:
   'Anyone mention Dr Paul Kreuger to you?'
   'No. Why should they? I've heard of him, of course.
   'I just wondered. A lot of strange things have been going on, and I doubt if we'll ever know all the answers.
   'Anyway, it's no secret now, so it doesn't matter. Two years ago I sent a confidential message to Paul – oh, sorry, I should have mentioned – he's my uncle – with a summary of my findings. I asked if he could explain them – or refute them.
   'Didn't take him long, with all the byte-bashing he's got at his fingertips. Unfortunately, he was careless, or someone was monitoring his network – I'm sure your friends, whoever they are, must have a good idea by now.
   'In a couple of days, he dug up an eighty-year-old paper in the scientific journal Nature – yes, it was still printed on paper back then! – which explained everything. Well, almost everything.
   'It was written by a man working in one of the big labs in the United States – of America, of course – the USSA didn't exist then. It was a place where they designed nuclear weapons, so they knew a few things about high temperatures and pressures.
   'I don't know if Dr Ross – that was his name -had anything to do with bombs, but his background must have started him thinking about conditions deep down inside the giant planets. In his 1984 – sorry, 1981 – paper – it's less than a page long, by the way – he made some very interesting suggestions...
   'He pointed out that there were gigantic quantities of carbon – in the form of methane, CH4 – in the gas giants. Up to seventeen per cent of the total mass! He calculated that at the pressures and temperatures in the cores – millions of atmospheres – the carbon would separate out, sink down towards the centres and – you've guessed it – crystallize. It was a lovely theory: I don't suppose he ever dreamed that there would be a hope of testing it.
   'So that's part one of the story. In some ways, part two is even more interesting. What about some more of that coffee?'
   'Here you are; and I think I've already guessed part two. Obviously something to do with the explosion of Jupiter.'
   'Not explosion – implosion – Jupiter just collapsed on itself, then ignited. In some ways, it was like the detonation of a nuclear bomb, except that the new state was a stable one – in fact, a minisun.
   'Now, very strange things happen during implosions; it's almost as if pieces can go through each other, and come out on the other side. Whatever the mechanism, a mountain-sized piece of the diamond core was shot into orbit.
   'It must have made hundreds of revolutions – been perturbed by the gravitational fields of all the satellites – before it ended up on Europa. And conditions must have been exactly right – one body must have overtaken the other, so the impact velocity was only a couple of kilometres a second. If they'd met head-on – well, there might not be a Europa now, let alone Mount Zeus! And I sometimes have nightmares, thinking that it could very well have come down on us...
   'The new atmosphere may also have buffered the impact; even so, the shock must have been appalling – I wonder what it did to our Europan friends? – it certainly triggered a whole series of tectonic disturbances, which are still continuing.'
   'And,' said Floyd, 'political ones. I'm just beginning to appreciate some of them. No wonder the USSA was worried.'
   'Amongst others.'
   'But would anyone seriously imagine they could get at these diamonds?'
   'We've not done so badly,' answered van der Berg, gesturing towards the back of the shuttle. 'In any case, the mere psychological effect on the industry would be enormous. That's why so many people were anxious to know whether it was true or not.'
   'And now they know. What next?'
   'That's not my problem, thank God. But I hope I've made a sizeable contribution to Ganymede's science budget.'
   As well as my own, he added to himself.

54 – Reunion

   'Whatever made you think I was dead?' cried Heywood Floyd. 'I've not felt better for years!'
   Paralysed with astonishment, Chris Floyd stared at the speaker grille. He felt a great lifting of his spirits – yet also a sense of indignation. Someone – something – had played a cruel practical joke on him; but for what conceivable reason?
   Fifty million kilometres away – and coming closer by several hundred every second – Heywood Floyd also sounded slightly indignant. But he also sounded vigorous and cheerful, and his voice radiated the happiness he obviously felt at knowing that Chris was safe.
   'And I've got some more good news for you; the shuttle will pick you up first. It will drop some urgent medical supplies at Galaxy, then hop over to you, and bring you up to rendezvous with us on the next orbit. Universe will go down five orbits later; you'll be able to greet your friends when they come aboard.
   'No more now – except to say how much I'm looking forward to making up for lost time. Waiting for your answer in – let's see – about three minutes...'
   For a moment, there was complete silence aboard Bill Tee; van der Berg dared not look at his companion. Then Floyd keyed the microphone and said slowly: 'Grandad – what a wonderful surprise – I'm still in a state of shock. But I know I met you here on Europa – I know you said goodbye to me. I'm as certain of that, as I'm sure you were speaking to me just now...
   'Well, we'll have plenty of time to talk about it later. But remember how Dave Bowman spoke to you, aboard Discovery? Perhaps it was something like that.
   'Now we'll just sit and wait here until the shuttle comes for us. We're quite comfortable – there's an occasional quake, but nothing to worry about. Until we meet, all my love.'
   He could not remember when he had last used that word to his grandfather.

   After the first day, the shuttle cabin began to smell. After the second, they didn't notice – but agreed that the food was no longer quite so tasty. They also found it hard to sleep, and there were even accusations of snoring.
   On day three, despite frequent bulletins from Universe, Galaxy and Earth itself, boredom was beginning to set in, and they had exhausted their supply of dirty stories.
   But that was the last day. Before it was over, Lady Jasmine descended, seeking her lost child.

55 – Magma

   'Baas,' said the apartment's master comset, 'I accessed that special programme from Ganymede while you were sleeping. Do you wish to see it now?'
   'Yes,' answered Dr Paul Kreuger. 'Speed ten times. No sound.'
   There would, he knew, be a lot of introductory material he could jump, and view later if he wished. He wanted to get to the action as quickly as possible.
   Credits flashed up, and there on the monitor was Victor Willis, somewhere on Ganymede, gesticulating wildly in total silence. Dr Paul Kreuger, like many working scientists, took a somewhat jaundiced view of Willis, though he admitted that he performed a useful function.
   Willis abruptly vanished, to be replaced by a less agitated subject – Mount Zeus. But that was much more active than any well-behaved mountain should be; Dr Kreuger was astonished to see how much it had changed since the last transmission from Europa.
   'Real time,' he ordered. 'Sound.'
   '...almost a hundred metres a day, and the tilt has increased fifteen degrees. Tectonic activity now violent – extensive lava flows around the base – I have Dr van der Berg with me – Van, what do you think?'
   My nephew looks in remarkably good shape, thought Dr Kreuger, considering what he's been through. Good stock, of course.
   'The crust obviously never recovered from the original impact, and it's giving way under the accumulated stresses. Mount Zeus has been slowly sinking ever since we discovered it, but the rate has speeded up enormously in the last few weeks. You can see the movement from day to day.'
   'How long before it disappears completely?'
   'I can't really believe that will happen...'
   There was a quick cut to another view of the mountain, with Victor Willis speaking off camera.
   'That was what Dr van der Berg said two days ago. Any comment now, Van?'
   'Er – it looks as if I was mistaken. It's going down – quite incredible – only half a kilometre left! I refuse to make any more predictions...'
   'Very wise of you, Van – well, that was only yesterday. Now we'll give you a continuous time-lapse sequence, up to the moment we lost the camera...'
   Dr Paul Kreuger leaned forward in his seat, watching the final act of the long drama in which he had played such a remote, yet vital role.
   There was no need to speed up the replay: he was already seeing it at almost a hundred times normal. An hour was compressed into a minute – a man's lifetime into that of a butterfly.
   Before his eyes, Mount Zeus was sinking. Spurts of molten sulphur rocketed skywards around it at dazzling speed, forming parabolas of brilliant, electric blue. It was like a ship going down in a stormy sea, surrounded by St Elmo's fire. Not even Io's spectacular volcanoes could match this display of violence.
   'The greatest treasure ever discovered – vanishing from sight,' said Willis in hushed and reverential tones: 'Unfortunately, we can't show the finale. You'll soon see why.'
   The action slowed down into real time. Only a few hundred metres of the mountain were left, and the eruptions around it now moved at a more leisurely speed.
   Suddenly, the whole picture tilted; the camera's image stabilizers, which had been holding their own valiantly against the continuous trembling of the ground, gave up the unequal battle. For a moment it seemed as if the mountain was rising again – but it was the camera tripod toppling over. The very last scene from Europa was a close-up of a glowing wave of molten sulphur, about to engulf the equipment.
   'Gone for ever!' lamented Willis. 'Riches infinitely greater than all the wealth that Golconda or Kimberley ever produced! What a tragic, heartbreaking loss!'
   'What a stupid idiot!' spluttered Dr Kreuger. 'Doesn't he realize...'
   It was time for another letter to Nature. And this secret would be much too big to hide.