The Long March 9c completed its final burn, bringing it into orbit around the moon. The six astronauts on the Harmony Space Station, along with millions of people down on the planet below, stared in astonishment at the image being sent back by the spacecraft’s camera. This close, the clouds shrouding the moon rushed past below like a torrent of muddy water from a bursting dam, lit almost continually from within by flashes of lightning so that it looked as though some titanic battle was being fought on the unseen surface, with each flash being an artillery strike.

“Dear God!” said Susan, her eyes wide with fear. “It must be hellish down there!”

“The temperature at the surface, at that location, is higher than the boiling point of water,” said Yu Han, watching another screen where columns of numbers were marching steadily downwards. “Across the whole of the moon, it varies from fifteen hundred degrees Celsius at the magma ocean to minus one hundred degrees on the other side, where the sun has not yet risen. It would be colder, but the atmosphere is transferring heat across the surface. The difference in temperature is causing winds to blow across the moon faster than the speed of sound. About ten thousand lightning bolts are striking the surface of the moon every second...”

“Alright!” cried Susan, making the others stare at her in alarm. “I get it!”

She wiped a hand across her face and Paul saw that she was trembling. “You okay?” he said, putting a hand on her arm.

“Yes,” she said, putting her own hand on his. “I'm sorry,” she said to Yu. “I didn't mean to snap.”

“Think nothing of it,” said the Chinese woman, smiling.

“It’s just that, I'm terrified of lightning,” said Susan. “You must think that's pretty funny...”

“Not at all,” said Paul. “I'm scared of spiders, so I can't laugh.”

Susan smiled at him. “Whenever there’s a thunderstorm, I have to close the curtains and turn off everything electronic. I know there are ground wires and surge protectors that can handle any lightning strike. I know it up here...” She tapped her head.

“Well, all that lightning is a hundred and fifty thousand kilometres away,” said Paul. “No matter where you are on Earth, there’s always lightning striking somewhere a hundred times closer than that...”

“Not helping, Paul,” she said with a smile.

“Yes, sorry. Hey look! The clouds are thinning!” He pointed back at the screen, and they saw that the clouds were indeed growing ragged, with gaps appearing in it. A dull, red glow appeared, shining up from below, and then they were past the clouds, with a clear view of the lunar surface. Paul felt Susan’s hand tightening on his and growing slippery with nervous perspiration.

The surface was completely molten. Magma, so hot that it flowed like water, with waves dozens of miles high blown across it by the supersonic wind. Spray was whipped up from the tops of those waves and blown high up into the air where it solidified into particles of solid stone moving with such speed that it would have pulverized any solid surface it encountered. There were no solid surfaces here, though. Nothing but blindingly bright magma on which small islands of semi solid rock would temporarily form, only to instantly sink and melt again.

“The winds are comparatively gentle there,” said Yu, speaking with a matter of fact voice that made Susan want to slap her. “At the surface, the winds are converging from all directions and slowing. Then they're heated by the molten rock and rise to begin the return journey to the moon's cold, solid side.”

“Doesn't look gentle to me,” said Benny, his wide eyes fixed on the screen. “I was in a hurricane once, at sea. At the time, I thought nothing could compare to the violence of the ocean that day, but it was a millpond compared to that!”

“It seems to be dying down, though,” said Jayesh. “Or perhaps it’s my imagination...”

“No,” said Yu. “The ship is approaching the centre of the magma ocean, where all the winds meet. One of only two places on the moon where the air is almost still. There, and the antipodes where the surface winds begin.”

“There must be one hell of a wind shear between high altitude hot air heading away from the magma ocean and low altitude cold air heading back towards it,” said Koshing. “There must be a whole series of concentric horizontal vortices. If the atmosphere were transparent, the two opposing faces of the moon would look like dartboards. Circles around circles, and each circle a horizontal tornado eating its own tail. The pressure so low at the centre that it is almost a pure vacuum.”

“I'm sure this is absolutely fascinating to you,” said Susan, “But all I see is a terrifying manifestation of the power of God People mock him and deny him, but now we see the power He is capable of wielding when He so chooses. Who can look upon that and not tremble at the thought of earning His displeasure?”

“I wonder what terrible sin the moon people committed to earn that much displeasure?” said Paul with a smile.

Susan shot him a look of venomous fury, but then apparently decided that it would be beneath her dignity to respond. She turned to Koshing again. “When will your people turn the device on?” she asked.

“Soon,” said the engineer. “They’re probably doing the last minute checks right now.”

Paul turned on his tablet and used it to listen to a BBC broadcast. The commentator was describing the same scene they were seeing on the viewscreen, for the benefit for anyone who wasn’t able to see it for themselves. Paul imagined there must be some such people somewhere. Bush people in the Kalahari, perhaps, or some Amazonian tribe still living in their traditional way despite wearing shorts and tee shirts. His every other word was a superlative or an expression of astonishment spoken rapidly and with breathless excitement. Atmospheric scientists must be having a field day, he thought. Give it a few years and the moon would be surrounded by a whole flotilla of weather satellites studying the dynamics of the moon's new atmosphere. That was if the human race avoided being thrown back to the stone age by the twice monthly cataclysms it would now be suffering if the Chinese device failed to work. Which it would. Because it couldn't work! It just wasn't possible!

“The Chinese seem pretty confident that it'll work,” said Benny, and Paul realised he'd spoken aloud.

“I suppose they must have tested a prototype,” said Jayesh. He looked over at their two new Chinese companions.

“I suppose,” said Koshing. “We know nothing about that, though. We were just told to fly it up here and build it. That’s all we know...”

He was interrupted by the voice of George Jefferson from ground control coming from the speaker. “How you doing up there, guys?” he asked.

“A little scared,” admitted Paul. “You looking at what we’re looking at?”

“I think everyone is,” George replied. On the monitor, the magma ocean was growing wild and turbulent again as the spacecraft left the doldrums and began passing over thundering winds again. On the horizon ahead, they could see the edge of the cloud cover that still covered most of the small world, flickering with lightning. “I just called to let you know that the Chinese will be turning on their device at eighteen hundred hours UTC. Any time now, in other words. They'll be turning it on and off every five minutes to stop the moon blowing itself apart. It's possible you'll feel some turbulence up there. The boffins tell me that you might actually be able to feel the moon's gravity as it comes and goes.”

“Thanks for the warning,” said Paul.

“We'll be keeping an eye on you from down here, seeing if your orbit is affected. The Chinese say they may have to adjust the timing of their device as they observe what it does to the moon, so it’s impossible to calculate your new orbit in advance. We'll advise you if you have to make a course adjustment.”

“It'll affect the Long March a lot more, won't it? While the device is turned on, it won't be in orbit around the moon.” Listen to me, he thought in astonishment. Talking as though such a thing is actually possible.

“The Chinese say they've taken that into account. And they’ve still got enough fuel for course corrections, if it becomes necessary. Okay, brace yourselves. They're turning it on in ten seconds. Sorry we couldn't give you more warning, we‘ve only just found out ourselves.”

“No worries, George.”

Instinctively, they all reached out to grab hold of something, as if they were on a bus that was about to turn a sharp corner. Paul smiled. Even with the moon this close to the Earth, the gravity they were feeling from it was thousands of times less than the gravity they were feeling from the Earth. They weren't going to be slammed against the walls or anything...

Except that he did feel something, unless it was just his imagination as the digital clock on the wall showed six o’clock. What was happening to the moon was definitely not his imagination, though. Beneath the spacecraft, the magma ocean leapt upwards! Paul was reminded of the war films where a destroyer was depth charging a submarine, except that the entire magma ocean rose at once, all four million square kilometres of it! He turned to another screen that was showing a real time image of the moon as seen by one of the few remaining satellites still orbiting the Earth.

It was visibly growing in size, but that was just the atmosphere ballooning outwards, he knew. As it rose it slowly lost its opacity, allowing them to see through it, and as the long minutes passed he found he could begin to see the old familiar features of the moon's surface, the first time they'd been visible since the impact of the Scatter Cloud. Craters and maria gradually came into view on the side of the moon opposite the magma ocean as the atmosphere continued to lift and thin. Paul felt his heart lifting at the sight of them, as if some long, terrible nightmare was finally coming to an end. On the other side of the moon, though, the magma ocean flared a brilliant, incandescent white and streamers of material leapt upwards, out into space...

And then it stopped. The streamers faltered, then began to fall again. The magma ocean flared even brighter as material that had risen above it fell back down. The atmosphere thickened and condensed again, once again hiding the surface from sight. A few minutes later the moon was as it had been before, the weather patterns they'd been commenting upon a few minutes before reasserting themselves before the Chinese turned their device on again and the whole thing repeated itself.

Paul became aware of a sharp pain on his arm. He looked and saw Susan's hand clamped upon it so tightly that her fingers were white. “It works,” she whispered, her face pale with what looked like shock and despair. “It works.”

He misunderstood at first. “Yeah. Who'd have believed it? The thing actually works!” He looked over to where Yu and Koshing were beaming with delight. “It actually works! Your scientists actually did it!”

“You should not underestimate Chinese science,” said Koshing, grinning broadly.

“I never will again! Fantastic, eh, Susan?” He looked back at her, and found her staring blankly back at him. She looked like a survivor of a tragedy, someone who’d seen dozens or people dying around her. “Susan? You okay?”

“It works,” she said again.

“Yeah. That’s good, isn't it?”

She stared at him for a few moments longer, then blinked and shook her head as if to drive out the memory of a nightmare. “Yes, yes of course Of course it’s good.” She tried to smile at him, but it only deepened his worries.

“What’s wrong, Susan? What is it?”

“Nothing’s wrong. This is wonderful! So many lives will be saved.”

“Yes, they will. There'll still be earthquakes and flooding, of course. They can't leave the device turned on for too long at a time, but the impact, the damage down on Earth will be far less than it would have been. It's a tremendous achievement!”

“Such power,” said Benny breathlessly. The others had been too enraptured by the images on the monitors to notice what was happening between Paul and Susan, but Benny’s words made Paul look at Susan again, thinking he now understood. Yes, of course! The power to do this to a whole world! That was what had terrified Susan. Who wouldn't be terrified by such a demonstration of power? Paul was trembling with awe himself!

“Such power,” said Benny again. “In the hands of the Chinese.”

Both Chinese engineers immediately turned to look at him. “What do you mean by that?” asked Koshing.

Benny seemed surprised to find that he’d spoken out loud.” Er, nothing,” he said. “I didn’t mean anything by it.” He fixed his attention on the monitor, where the magma ocean was erupting again as the operator down in China turned the device on again. After a couple of moments he looked back at the Chinese crew members to find Yu's dark, narrowed eyes still fixed on his, staring with a disturbing intensity. “I'm sorry!” he said. “I didn't mean anything by it. Honestly!” She looked at him for a few moments longer, then turned away.

Susan reached out to a handheld to turn herself around, then kicked herself off towards the hatch. “Where are you going?” asked Paul.

“I'm feeling a little tired,” she replied. “I just want to lie down for a while.” She pushed herself off and swam through the hatch.

“We all have duties we should be getting on with,” said Jayesh, turning to follow after her. “Can’t sit here staring at the show all day.”

Benny also turned to leave, feeling an urgent need to distance himself from the a Chinese for a while, but Paul, Yu and Koshing remained where they were, watching as the moon continued to beat like a titanic heart as it swept down towards the Earth.

☆☆☆

“It’s working!” said Ben in astonishment. “It's actually working!”

The Wetherby team, including a number of junior researchers but minus Eddie and Frank, was watching the BBC's coverage of the moon on the large screen in the common room. The commentator was almost having fits of jubilation as he described what was happening to the Earth’s natural satellite, with experts sitting in a studio giving their own interpretation of events. Occasionally, the coverage would switch to a reporter standing in a street pointing to the wet, sandy tarmac under his feet and explaining how it had been under water just minutes before. All around the world, high tides were subsiding to levels that were still high enough to breach sea defences but nowhere as high as they had been before. Elsewhere, large areas of seabed that had been left high and dry were being inundated again as the seas flowed back. One reporter, flying over the Atlantic in a light aircraft, was pointing down to the wreck of a German U-boat half buried in the mud off the coast of Newfoundland. Water was swirling around it. The wreck would be under water again within mere minutes.

“All that power, flowing through the mass dampener!” said James breathlessly. “And it’s taking it! Vastly, incomprehensibly more power than it was ever designed to take, and it’s taking it!”

“Well, we don't know how much power it was designed to take,” pointed out Alice. “For all we know, it’s an off the shelf component that was originally designed to move planets around. The spaceship might have been feeding it only a tiny fraction of the power it was designed to take. Maybe the wonder isn't that it can take so much power but that it could function while taking so little.”

“But was it designed to be turned on and off again so frequently?” asked Ben. “With human tech, the turning it on is usually when it’s taking the most stress.”

“If it really was designed to move planets around, then it would have to be repeatedly turned on and off,” said Alice. “To stop the planet from blowing itself apart. It would have been designed to cope.”

“If that was what it was designed for,” said Karen.

“What worries me,” said Ben, “is that every time they turn it off and everything falls back down, it’s adding a tremendous amount of energy to the moon. They'll make it melt faster.”

“Does that matter?” asked Alice. “Who cares if it melts?”

“Because it'll heat up the Earth. Having a ball of molten rock three thousand kilometres across pass a hundred thousand kilometres from the Earth every fifteen days, it’ll be like standing too close to a bonfire. We'll be able to feel the heat. What's left of the ice caps will go. Sea levels will rise not just twenty metres but sixty metres!”

“It could make things worse?” said Jessica, staring at him.

“But there wouldn't be the earthquakes,” pointed out Alice. “Or not so bad, anyway. And the sea levels would be steady at sixty metres higher, or almost anyway. Rising and falling only by ten metres, not twenty. It would still be an improvement.”

“You're still not thinking far enough ahead,” said Ben, though. “If the Chinese keep using the mass dampener, the moon will keep heating up. Eventually it will completely vaporize.”

“I think you’re being a bit dramatic...” began Alice.

“Am I? If you keep adding energy, what happens? Eventually the moon will vaporize. It's a mathematical certainty. Eventually it will have enough energy that its gravity won't be enough to hold it together even when the device is turned off. The moon will just puff apart!”

“Well, that would be one solution to the problem...”

“No, it wouldn't. It would be the beginning of the end. When the vapour puffs out into a large enough volume, it'll be too big for the mass dampener to affect all of it, no matter how much energy they pump into it. And then the vapour will cool and recondense. Not just into one moon but thousands of them. All jostling each other with their gravity. Some will be flung out into the solar system, and others...”

“Will fall down to Earth!” said Jessica, her eyes widening with fear. “How big would they be?”

“At first, just dust and gravel,” said Ben, “But as the process of accretion continues there could be rocks miles across coming down. Each one a dinosaur killer. Eventually there could be rocks falling large enough to completely sterilize the planet.”

“No! No! That can’t be!” said Alice, though. “If that were so, one of them would have said so.” She pointed to the scientific experts sitting in the television studio, chatting amiably to the host of the TV show. “Look at them! They’re not worried!”

“They probably just haven't thought it through yet,” said Ben. “They will, though, and when they do there'll be an international outcry, a demand for the Chinese to stop what they’re doing! Maybe the Chinese will figure it out first. Maybe they’ll stop all by themselves.”

“You have to tell someone,” said Jessica. “The Americans. They'd love a chance to make the Chinese look bad.”

“I would hope that that wouldn't be their primary motive,” said Ben. “But you’re right, I have to tell people.” He reached into a pocket and pulled out his phone.

At that moment, Eddie and Frank burst in, looking excited. “We have an announcement!” said Eddie.

“You're getting married?” said Alice, grinning. “Congratulations!”

Eddie gave her a look of annoyance. “Seriously,” he said. “We've figured out a way to...” His words were rapid and blurred together in his excitement. He made an effort to speak slowly and clearly. “We've figured out a way to reverse the effect of the mass dampener. We can make it increase mass, not just lower it.”

“It works!” added Frank. “We've just tried it! It was Eddie's idea. God knows how he thought of it...”

“It just came to me,” said Eddie. “Right out of the blue. I figured out that if we fed the polarised phonons into the superfluid lens at an angle corresponding to the ancillary index...”

“Okay, slow down, slow down,” said Jessica. “We're not all physicist. I have no idea what you’re talking about. It works, you say?”

“It works!” said Frank, staring at her in delight. “We raised the mass of a ten kilogram weight to over twenty kilograms. The area of effect for the amount of energy you put in seems to be about the same...”

“Wait a minute!” said Ben, though. “You could only reduce mass by fifty eight percent. You can increase it by over two hundred?”

“There seems to be no limit to how much you can increase an object’s mass,” said Eddie. “And that’s important. Our prototype can, in theory, completely cancel out the effects of the original alien mass dampener.”

“Why is that important?” asked Alice.

“Because it means we can move the moon back to its original orbit!”

“No, we can’t,” said Frank, though. “We talked about this, remember? When the moon returns to its original distance from the Earth, the magma ocean will be on its trailing side. There’ll be no solid surface we can land and push on.”

Eddie just grinned wider, though. “So we don't push,” he said. “We pull. We land our rocket on the leading hemisphere, attach it to the moon with a stout chain and pull.”

“And how do we get our rocket to the moon? If we’re really, really lucky there might be a rocket sitting on a launch pad somewhere that can get a man up into space, but only to earth orbit. You’d need a lot more fuel to get him to the moon. That would take a special mission that would take years to prepare. We've got a few days before the moon melts completely, turns into a globe of magma. It can't be done!”

“There has to be a way! There's all kinds of stuff up in space already. The space station itself, two shuttles...”

“The shuttles only have enough fuel to de-orbit and return to Earth.”

“The space station has engines big enough to adjust its orbit, prevent it falling back to Earth. If one of those engines were to be attached to one of the shuttles, I'm sure it would have more than enough thrust to get it to the moon. The space station has an entire machine shop up there, I'm sure they could cobble something together.”

Ben stared at him as though he were mad. He looked for a moment as though he was about to say something scathing and sarcastic, but he held himself in check and made himself be more diplomatic. “In your excitement at your extraordinary achievement, you've overlooked the obvious,” he said. “The exhaust from your rocket would hit the moon’s surface. The momentum it gives the rocket would be exactly balanced by the momentum it gives to the moon. The rocket, moon system will go nowhere.”

Eddie was already grinning so widely that it didn't seem possible for it to grow any wider, but somehow he managed it. “With respect, old man, you’re the one who's overlooked something. We make the mass amplification field just big enough to surround the rocket, without touching any part of the moon. That way...”

The exhaust will have mass when it leaves the rocket,” said Ben, looking abashed. “When it hits the moon, though, it will be massless, or virtually so. It will give momentum to the rocket, but not to the moon.”

“No, no, wait a minute!” said Frank, though. “You could use that to create a reactionless drive! A spaceship that accelerates without losing any reaction mass! You could create a similar set up entirely within the outer skin of a spaceship. Collect the massless exhaust and recycle it when it has mass again.” He stared around at the others, and they stared back at him. “Reactionless drives are impossible!”

“It would appear not,” said Ben, though. “By manipulating mass, we can colonise the solar system. Maybe even create true starships, capable of crossing interstellar distances. Once you can lift unlimited masses from the ground into orbit, building a hundred thousand ton starship should be no harder than building an ocean liner.”

“We'd need to know exactly where on the moon to attach the chain,” said Alice.

“As close to the centre of the forward facing hemisphere as possible,” said Ben.

“Yes, but that still leaves us plenty of choice. You could probably attach your chain anywhere within a region a hundred kilometres across. We need to be able to choose a spot relatively free from earthquakes. Where the crust is still firm enough to make a good anchoring point, free from fault lines. You don't want to attach your chain to a lump of rock that just pulls out of the ground. You need to know that it's firmly attached to the entire moon.”

Ben nodded. “It seems we're going to need a moon expert,” he said.