“They're going to use one of the alien mass dampeners,” said Ben.

The others looked up as he entered the primary lab. Everything in the room was gleaming white or shining chrome, lit by the sun shining in through the long south wall that consisted almost entirely of windows. The air hummed with scientific machinery, and a pair of junior researchers standing beside the mass spectrometer were talking quietly as they studied the results of their latest test. They looked up at Ben's startling statement and came over to join the senior researchers, standing or sitting together on the other side of the room.

Eddie put down the tablet on which he'd been reading Frank's research notes and rose from the room's only padded armchair to join the others. Ben and Karen had spent most of the day making phone calls and attending teleconference meetings with civil servants and government ministers, trying to convince them that they might, just might, be able to push the moon back into its original orbit. Eddie, meanwhile, had started the long process of bringing himself up to speed on what the others had learned of the alien ship and its technology while the others had gone back to work. The statements issued by the Chinese, just under an hour before, had stunned them just as much as the rest of the world.

“Let me guess,” said Frank. “They're going to put it in orbit around the moon and supply it with enough power that its area of effect encompasses the entire moon?”

“Pretty much,” replied Ben, taking a seat beside the quantum microscope. “They're going to launch it from Wenchang on a Long March 9c along with two astronauts. It'll be assembled on the space station before being sent off towards the moon.”

“The 9c?” said James. “The super heavy launcher? The one they were going to use for the next mars mission?”

“Yeah. Lucky they had one on the launch pad, ready to go. It'll need that kind of thrust to reach the moon, the speed it’ll be going by then,” said Frank. “Assuming they want to reach it before its first perigee. Velocity difference is what counts in space, not distance.” The others nodded.

“How are they powering it?”

“Solar panels. Enough to provide a hundred kilowatts. They're using rooftop solar panels, the kind you put on your roof to power your home.”

“Heavy,” said Eddie. “Inefficient.”

“Yeah, but it would take months to build some proper space solar panels. They're doing the best they can with what they've got.”

“They’re taking the credit for inventing it!” said Frank. “I made the breakthrough! Me!”

“They may be doing it to protect us,” said Jessica. “To stop people from finding out about us, about this place. We always knew we’d never be able to take the credit for what we're doing here.” Frank nodded but didn’t look placated.

“They said they'll only be able to reduce the effect of the moon's gravity,” said Stuart. “Not eliminate it entirely. Does that mean they'll only be using it intermittently? Repeatedly turning it on and off again?”

Ben nodded. “As Alice pointed out, if you took away the moon's mass for more than a few minutes, its internal pressure would blow it apart. They're planning to turn it on and off every five minutes or so, with the option to adjust the time intervals as they observe what kind of convulsions the moon undergoes.”

“We have no idea whether the mass dampener can take the kind of power it would need!” protested Frank.

“Guess we're going to find out.”

“They could burn out one of the only two original devices in existence! Especially if they’re going to keep turning it off and on again. They'll be subjecting it to an intolerable insult every five minutes, presumably for ever. I assume they’re planning on leaving it there permanently?”

“That is my understanding,” said Ben. “They'll probably turn it off as it recedes from the Earth again, keep it until the next close approach. Maybe that'll prolong its life.”

“If it doesn't, you can't just pop down to the hardware store and buy another,” protested James. “My idea is still better. Push the moon back to its original orbit. That way, the dampener only has to work for a few hours. If it burns out after that, it doesn’t matter. The way the Chinese are doing it, it has to work forever!”

“We've still got the exhaust problem, remember,” pointed out Alice. “The mass of the rocket exhaust would also be dampened, and by the same amount. It wouldn’t be able to push anything!” Eddie looked up for a moment, as if he was about to say something, but then he changed his mind and looked away.

“Could it actually work?” asked one of the junior researchers, his eyes wide with hope.

“We know virtually nothing about this technology,” said Karen. “Maybe it’ll burn out the moment they turn it on, maybe it’ll last for a million years. We won't know until they actually do it.”

“It's crazy and irresponsible,” said James. “If they misjudge it, leave the device turned on too long, an eruption could throw thousands of cubic kilometres of magma out into space. A few orbits from now, enough of it could hit the Earth to destroy everything!”

“Who will be in charge of it?” asked Alice. “Who'll be throwing the switch?”

“Some senior Chinese government official, I expect,” said Ben. “Acting on sound scientific advice, I would hope.”

“The Chinese would be able to hold the world to ransom! They could turn the device off when the earthquakes and high tides hurt their enemies more than them!”

“I think geography is against that happening,” said Karen, though. “The people they hate the most are either their neighbours, like the Japanese, the Russians, or directly on the other side of the world from them, by which I mean the USA. They can’t hurt them without hurting themselves.”

“They might think they can ride out the storm better than their enemies. China is a huge country, with vast areas a long way from the coast and any earthquake zones.”

“So are the USA and Russia. Forget it, a tide weapon is pretty much impossible. They'd be cutting their own throats.”

“Even so, the other governments of the world are likely to insist that the device be placed under international control. There could be conflict over it.”

“Nothing we can do about that,” said Karen. “Let the politicians worry about it.”

“Yeah, because they never screw up.”

“I have another concern,” said James, turning his wheelchair to face Ben. “The device will be controlled by radio from China, right? What if some snot nosed sixteen year old hacks it from the computer in his bedroom and leaves the device turned on permanently? The moon blows up, and the next orbit around a large proportion of it hits the Earth.”

“I doubt the device itself would survive the destruction of the moon,” said Frank. “At the very least, the solar panels would be hit by debris and the device would lose power. All the pieces of the moon would get their mass back and gravity will pull it all back together again.”

“Not all of it.” said James. “A lot of it would be slingshotted away by larger fragments and remain in independent orbits around the Earth. Some of it would be bound to hit us. The safest thing to do might actually be to leave the moon alone. To just adapt to life with the moon in its new orbit.”

“Does that mean you're no longer in favour of pushing the moon back into its old orbit?”

“That way, with our plan, the device would only be turned on for a few hours, at most. Far less time for some hacker to break into the system. And it would be four hundred thousand kilometres away. Also, we could safeguard the system by connecting it to a timer that cannot be overridden, a timer that turns the device off permanently after six hours. Even if the moon does blow up in that time, all the pieces will still be close enough together that none of it will be able to escape its collective gravity.”

“The downside is that we have to wait for the moon to return to its original distance before we push it,” pointed out Ben. “We can't avoid letting it make at least one close pass by the Earth. The damage caused by even one perigee tide would be incalculable! The Chinese plan, if it works, would save the Earth from most of that.”

“Perhaps a combined plan,” said Eddie, speaking for the first time. “Use the Chinese plan for the close approach, then push the moon when it returns to its original position.”

“The rocket exhaust would still be massless...” began Alice. Eddie nodded furiously at her to tell her that he hadn't forgotten. He went back to where he'd left his tablet and turned it back on, collapsing back into the padded chair.

“They want to launch in two days time,” said Ben. “Then they'll have just twenty four hours to assemble it before it has to be sent off to the moon. If they miss their window, they'll have to wait for the next orbit.”

“Gods, they’ll pull out all the stops to meet the deadline!” said Frank. “They've pinned all their national pride on it. Failure now would be a colossal embarrassment. People will, literally, pay for it with their lives!”

“And when you're in that kind of a rush, you make mistakes,” agreed Stuart. “Is there any way we can help them? We know more about mass dampeners than anyone.”

“I offered them our help,” said Ben. “They said they’d ask for it if they needed it. That's code for keep your noses out of our business.”

“They want all the glory for themselves,” said Stuart. “If it actually works, they'll be able to brag about it for centuries! They'll never let the rest of the world forget it.”

“Let them,” said Ben. “I, for one, will be wishing them luck. I know the rest of you will be as well.”

“Yes, of course,” said Stuart. “I just can't stop thinking of all the things that can go wrong, though. God, this is one hell of a gamble they’re taking!”

The others nodded their unhappy agreement, and one by one they drifted back to their work.

☆☆☆

“Get out your best china, Paul,” said George Jefferson from the monitor screen. “You're getting visitors.”

“Yeah,” said Paul, floating in the command module. “We saw. It’s really happening, then?”

“So it seems. They're sending a ship up, anyway, with a couple of guys and a bunch of equipment. They're expecting to be with you forty two hours from now.”

Paul glanced up at the clock. “Anyone we know?”

“The name of Yu Han was mentioned. She's their best space engineer. Did a lot of work on their own space station, back in the day.” Paul nodded. Space stations were expensive, and having one all to themselves had turned out to be a luxury the Chinese couldn't afford. Their national pride was saved by the fact that no-one else could afford one all to themselves either. That was why they and the Europeans had built Harmony together, along with some cash from the USA who wanted to keep a toehold in space despite having lost almost all interest in anything outside their own country.

The Chinese space station was still out there, floating empty. Every so often the Chinese talked about putting a crew back aboard it, but the expense of getting it operational again had always been prohibitive, and getting more so all the time as it continued to take damage from space debris. Everyone expected then to de-orbit it eventually. Burn it up in the atmosphere before it broke up and became a hazard to everything else in orbit.

“I met her once,” said Paul. “In Madrid, at a publicity thing. They were trying to get some private companies interested in space again. Nice girl. Charming, good with the press. Knows her stuff too. Who's coming with her?”

“Some guy called Koshing Goushi. Know him?”

“Nope. I assume he's the pilot?”

“No, he's another engineer. They're not bringing a pilot, they don't need one. Get this. They're not coming up in a shuttle. They're coming up in a capsule, like in the old days.”

“You are shitting me!”

George chuckled. “I'm really not. They're coming up in an old Shenzou capsule, perched on top of a Long March 9c. They won't be going home on it, they’ll be staying up there with you until you all come home together. They'll just jettison the capsule after, let it burn up.”

“They just happened to have a capsule standing by, ready?” Susan appeared in the hatch. Paul beckoned for her to join him.

The face on the monitor screen chuckled again. “You won't believe this, Paul. It's an old capsule. A used one, I mean. It's the capsule from the aerospace museum in Beijing. Used for a mission to their space station in 2035.”

“But they’re not reusable!”

“All its got to do is be airtight. It won't have to bring anyone back to earth. There's no need to replace the heat shield, the parachute, the soft landing rockets, anything. They’re dusting it off, doing a few repairs...”

“A few repairs!” Paul realised that George was still speaking. Even after all these months, he still hadn’t gotten used to the speed of light delay. “A few repairs?” he repeated. “Is it still spaceworthy?”

“The Chinese seem to think it is. Yu and Koshing are willing to take the risk, apparently.”

“Rather them than me. They say they’re going to reduce the mass of the moon! Are they insane, or is it me?”

“The Chinese are dead serious. They've announced a press conference in which they’ll demonstrate the device.”

“But it can't work! It's impossible!” He glanced across at Susan, who was listening to the exchange in silence. “What do you think?” he asked her.

“If it’s God’s will, it’ll work,” she said.

Paul nodded. He really hadn’t needed to ask. “Well, we'll get the guest quarters swept out,” he said. “Tell cook it’ll be six for dinner tomorrow.”

George smiled back at him. “I'll let them know it’s a formal affair. I'll keep you informed of any developments.”

“Okay. Take care down there.” Paul reached out and cut the connection. “So,” he said. “Guests.”

“Good “ said Susan. “Did I hear you saying they’re both engineers?”

“Qualified space engineers. Fully qualified to do any spacewalking that needs to be done.”

She smiled with relief. “Good! I'll be very happy to leave it all to them.” She pushed herself over to the window and peered through it. The moon hung there, still almost full, an almost featureless dull grey disc. Its eastern face was slightly mottled with the tops of convection cells, the dark lines separating them forming an almost regular hexagonal grid. The very slightest hint of movement could be seen. Susan had seen a time lapse movie of the moon, and it had looked like a pan of boiling water flickering with lightning bolts. It had looked angry, she remembered thinking. It had looked fucking pissed!

“When it makes its closest approach,” she said, “will we be in danger? The first Scatter Cloud almost made us fall out of the sky. What will the moon's gravity do to us?”

“Nothing,” replied Paul. “No need to worry about that, at least. We're too low, the Earth has us in too tight a grip. The first Scatter Cloud went right past us, really close. The moon will be much further away.”

“Not far enough away for my liking. I was talking to Benny earlier. He wants us to take the shuttle and go home. All of us.”

“Yeah. He spoke to me too. We can't go now, of course. Not with the Chinese on the way. They'll arrive up here and have no way to get back home.”

“We could go now, before they lift off. The Chinese won't come if there’s no way home.”

Paul turned to look at her. “They might. They really might. They might be prepared to wait until they send the mule to refuel the Jinlong. And if that can't be done, they might come anyway. They might be prepared to make that sacrifice if they think they can actually do what they say they can do.”

“But they can't! It's impossible! It's complete fantasy!”

“What if it’s not? What if they really can do it?”

“But you can't! You can't just take away an object’s mass! And even if you can, if you can somehow do something in a lab to make a small object massless, we're talking about the whole fucking moon!”

“The Chinese premiere was prepared to stake his personal reputation on it. You know how important reputation is in China. If your reputation is damaged, it can be the end of your career, and Jiang Deyao is leaving himself wide open to the biggest humiliation in history. If it turns out he's been fooled by some clever opponent he’ll probably kill himself. He knows what the stakes are, and he did it anyway, went out on a limb in front of the whole world. He wouldn't have done that unless he was pretty bloody sure of what he was doing.”

Susan stared at him. “But they're talking about making the whole moon massless! What part of that seems even the smallest bit plausible to you?”

“It does seem incredible,” Paul agreed. “But if there's even the smallest chance they can do it...”

“But there isn't! You just can't do something like that!”

“Then they’ll fail spectacularly. The Chinese will be humiliated, Jiang Deyao will kill himself in some public way and we’ll go home in the shuttle. All six of us.”

“Promise?” said Susan, kicking her way through the air towards him. She grabbed his arms and brought her face close to his, looking him straight in the eyes. “You promise? If the Chinese fail, we take the Colibri and go home right after, whether Philip Carver agrees or not.”

“I promise,” said Paul. “If the Chinese fail, we take the shuttle and go home. Not a word to anyone on the ground, though. If they find out we're thinking of abandoning ship they might upload a software patch to take the shuttle out of our control. We keep it to ourselves. Okay?”

“Agreed ” She gave him a light kiss on the mouth. “I'll tell the others. Tell them what we've agreed and that we have to keep it to ourselves for now.” Paul nodded, and she kicked herself off towards the hatch, leaving Paul alone in the command module.

☆☆☆

Three hundred and sixty thousand kilometres away, the moon crept through space at just two thirds its usual speed relative to the Earth. A thick atmosphere of carbon dioxide and sulphurous gases, choked with volcanic dust, now covered the small world. On earth, the planet’s twenty four hour rotation meant that the weather was dominated by spiralling cyclonic systems, but the moon rotated on its axis twenty six times more slowly. The movement of its atmosphere was dominated by the rising of hot air on its eastern side, heated by the growing ocean of magma beneath it, and the sinking of cold air on its western side. Hot air passed from east to west high above the ground, cooled, sank and flowed back eastward close to the ground at hurricane speeds, picking up dust and carrying it back to the magma ocean so fast that features that had stood untouched for hundreds of millions of years were being sandblasted to destruction. The descent stages of the Apollo and Qianfeng landers had already been destroyed, along with all the equipment the astronauts had left on the surface. In places, where the wind was funnelled by mountains and crater walls, the wind was strong enough to roll even quite large boulders along the lunar surface. Overhead, as dust particles were rubbed together generating static electricity, the air was repeatedly split by titanic flashes of lightning, many times more powerful than anything ever seen on Earth. Thunderous crashes of thunder followed, shockwaves powerful enough to dislodge loose rubble and bring it tumbling down mountainsides in vast landslides that further added to the dust held in the atmosphere.

The magma ocean bubbled and boiled. The thick atmosphere above it acted as a blanket, holding the heat in, leaving it with nowhere to go but down and sideways, warming up and melting the still solid moonrock surrounding it. The hot rocks below the ocean were the first to melt, so that the ocean grew steadily deeper. Soon it would merge with the moon's tiny molten core. The sideways growth was slower, but no less relentless. Magma pushed its way through the tiniest faults and fissures, widening them, swallowing up the occasional lakes of molten rock kept hot by pockets of radioactive elements. A hundred miles below the surface, a layer of molten rock spread ever wider, increasing in depth as it melted rocks above and below until huge slabs of crust miles across broke off and sank, disappearing below the surface. It was a slow process, because magma is dense and viscous, only a little lighter than the solid rock above. Magma welled up through the newly made cracks, occasionally jetting up in huge geysers, and then the molten rock flowed slowly across the surface, converging upon itself in all directions, until the last island of solid ground was swallowed up.

As the moon crept through space, though, it was edging closer to the Earth. It was already closer than its original orbit had ever brought it, although it would have taken sensitive measuring equipment to see any increase in its size as seen from Earth. As it crept closer, though, it began to pick up speed, dropping ever faster towards the fragile blue globe that waited below...