The woman's yelp of terror woke him up.

Paul Lewis jerked awake, adrenalin flooding his body, ready to fly to the assistance of the women in distress, but then he relaxed as he remembered where he was and why his fellow astronaut was screaming. He chuckled to himself and allowed himself to relax back under the elastic webbing that was holding him in place in his cot.

Deep beneath the large frontal cortex of which humans were so proud, a primitive primate brain still lurked. So long as you were awake the frontal cortex was in charge. Sensible, rational. Fully aware of the circumstances in which it found itself. During the still half asleep part of waking up, though, the primate brain could briefly find itself fully in charge, just for a moment or two before the frontal cortex also woke up and took hold of the reins. Normally, that wasn’t a problem. The primate was content to just lie there, relaxing, enjoying the peace and quiet, but when you were in space, in free fall...

The feeling was quite unmistakable, even when strapped into a cot, elastic straps holding your body firmly onto the padded mattress. The internal organs, floating freely inside the body cavity instead of lying heavily against the spine and pelvis, created a ‘going too fast over a humpy bridge’ feeling that was the first thing you were aware of as you woke up. The primate brain only knew one reason for being in free fall. You’d fallen out of the tree in which you'd been sleeping and were about to hit the hard, African savannah floor. Injuries were sure to result. Broken bones that would leave you helpless to defend yourself against leopards and the other predators that had terrorised the prehistoric world. The primate brain went into full panic mode, therefore, until the frontal cortex woke up and took over.

“You okay?” asked Paul, struggling to keep the humour out of his voice. An embarrassed mumble came from the next cubicle and the curtain twitched as Susan Kendall unstrapped herself from the sleep webbing.

1“I thought I was over that!” she complained, her voice slurred and sleepy. “Two weeks since the last time. I thought, good, I'm finally adapting, my stupid brain's finally got the message.”

The curtain twitched again, and Paul imagined her putting on her tight sports bra, the only item of clothing capable of keeping her breasts from floating and bouncing in the weightless environment. Connie McCloud, an older, experienced astronaut, had recommended them to her, recounting her own experiences with wayward body parts during here own space missions, and Paul had never quite forgiven her for it.

The sports bra was too uncomfortable to wear at night, though, and so she took it off, leaving her male crewmates dreaming of a sudden emergency that would require her to leap out of her bunk and into action before she had the chance to dress...

Paul mentally scolded himself for his immaturity. I'm forty five years old! he told himself. I have a wife, two children and a grandchild! I'm too old to be fantasizing about tits like an adolescent! The attraction was too strong to ignore, though, except through the exertion of willpower. It was hardwired into the brain, a relic from infancy, when the baby's survival depended on finding a nipple and latching onto it. Or at least that’s the way it was for men. If the theory was true, he mused, you would expect an adult woman's eyes to be drawn to breasts in the same way, but he'd never found a woman who would admit to it. Perhaps they were afraid of being labelled lesbians, even today, in the middle of the twenty first century.

He made use of the small bathroom cubicle, then emerged and got dressed. The space station had two habitation modules, and occasionally the suggestion had been made to assign one as the men’s quarters and the other as the women’s, for reasons of decency and privacy. That might have worked if the station always had equal numbers of men and women aboard, but that would have meant choosing crews according to gender instead of ability, something that the high minded scientists had always resisted. That didn't mean that it was always men who were in the majority, though. There had been two six week periods in the five years since Harmony had been completed during which the women had outnumbered the men, and it was scheduled to happen again early next year, although Paul’s tour of duty would, sadly, have long ended by then.

After two months aboard the Harmony Space Station, he’d gotten good at getting dressed in zero gravity and he pulled on his one piece coverall with practised ease. While he was zipping up the front Susan emerged wearing her sports bra and a skimpy pair of briefs and took her turn in the bathroom cubicle. She glanced at him as she floated past, as if expecting him to ogle her or make a joking remark about her primate brain experience, but he just pulled his soft slippers onto his feet and adjusted his ankle cuffs around them for comfort, focusing his attention entirely upon this task until she was in the cubicle with the curtain drawn behind her.

Large though the space station was, it was impossible for them to get very far apart from each other and they were scheduled to be here for several weeks longer yet. They had to get along together, avoid annoying or embarrassing each other. He had to act the perfect gentleman, therefore, and so, as soon as he was finished dressing and combing his short cut hair, he pulled himself through the hatch into node five, then through one of its three other exits into the command module.

Lauren Kelly, the current station commander, and Zhang Yong, one of the shuttle pilots, were there waiting for him. “What have I missed?” he asked as he scanned his eyes across the main status monitor. Every light was either green or yellow, he saw, and the yellow lights were all on the bottom two rows, signifying minor systems, things that would be tackled by their routine maintenance schedules. In the weeks he’d been there, only one red light had ever appeared, and that had also been on the bottom row. A printed circuit board in the microwave oven that had overheated due to an accumulation of dust in the air vents. A quick once over with a vacuum cleaner had sorted it out.

“Up here, not much,” replied Lauren without taking her eyes from the monitor that had her attention. “There was a three percent drop in power from the solar panels while you were asleep. The power dropped in five discrete stages, as if they suffered some kind of minor damage.”

“Micro meteorites?” asked Paul, pushing himself over to look at her screen.

“That would be my guess. Punching holes in the panels. We may have passed through an uncharted meteor shower, too small to have been noticed before. There's been no drop in pressure anywhere in the station, so we weren't punctured.”

“I'll send the robot out to have a look.”

“Please send it to look at Tianshi as well,” said Zhang, looking up from the observatory station. “I wish to see if the heat shield was damaged.”

“The accelerometer didn’t register any impacts,” said Lauren, “but it’s still best to be safe.”

Paul nodded. “I'll look at the shuttle as well,” he said, grabbing a handhold to propel himself towards the ROMIS station. He guided himself into the chair, musing on how they still felt the need to be seated in order to do any kind of work in front of a computer screen, even in a weightless environment. It was necessary to be held in place, of course, to prevent oneself from drifting away from the touch pads, but was it really necessary for one's bottom to be in a seat? For the legs to be folded to make a lap? It felt comfortable and familiar, though. You could fool yourself into thinking that you were back on earth, in an office building, rather than hurtling through space at twenty thousand kilometres an hour, and perhaps that was the point. He belted himself in and brought up the diagnostic screen. “In fact, I'll look at the shuttle first, since it's one of our lifeboats.”

“Thank you,” said the pilot, turning back to his own work.

“Anything else?” asked Paul as the screen began to fill up with status reports.

“Up here, that’s about it,” Lauren and Zhang shared a look. “Things have been a bit more interesting down on earth, though.”

“Why? What happened?”

“The entire GPS system collapsed.”

“What?” Paul looked up in astonishment.

“It's been chaos down there! Ships and aircraft going off course, every stock market crashed simultaneously, trillions wiped from every major economy. They're talking about the biggest depression since the nineteen twenties!”

She reached over to the ROMIS workstation and touched a button. The diagnostic screen was immediately replaced by the BBC news front page, topped by the words ‘GPS CHAOS’ in screaming large type. Another, smaller headline read “Experts disagree on cause’, followed by an article in which the reporter gave a long list of possible causes that Paul could only assume he’d gotten from his tea lady.

“Sunspots?” he said. “A solar flare? Has there been a solar flare?”

“Nope,” said Lauren. “Zhang and I have a little bet on. He says terrorists hacked the GSA mainframe, while I say an engineer spilled a cup of tea over a workstation.”

“It wasn't terrorists,” said Paul confidently. “Terrorists are idiots. They plant bombs or shoot people. They don't have the nous for this kind of thing.”

“Nous?” asked Zhang.

“Know how, training. No, if it was sabotage it must have been a disgruntled former employee or something. Someone who knew the system. What about the other GPS systems? Your lot have one, don't they? The Chinese, I mean. And there’s a European system, a Russian system. There's about half a dozen GPS systems, aren't there? We were even thinking of creating one of our own, a couple of decades back. Britain, I mean. Back during that whole Brexit thing.”

“These days they're all interlinked,” replied Lauren. “They're all part of one big network, and all controlled from one place. I assume it made sense to someone, once.”

“What did?” asked Susan, joining them in the command module. She was wearing a set of coveralls identical to those worn by the others, except for the national flag on the upper arm. An American stars and stripes.

Lauren quickly filled her in on what had happened and her eyes widened with shock. “Are we in danger?” she asked.

“No,” said Lauren. “They use radar to fix our location, and our communications are secure. We're in no danger...”

The uplink from Canberra chose that moment to bleep, signalling that a message was coming in and that they had to drop whatever they were doing and pay attention. “Harmony station, Harmony station, this is Canberra. You still up there?”

Lauren touched a screen beside the speaker. “This is Harmony station. We're still here. That you, George? How you doing down there?”

“We're fine, Lauren. The power grid's crazy, we're on emergency generators here. Most of us had no idea that so many things were dependant on the GPS system. Listen, we don't have time for the usual light hearted banter, you have to make an emergency course correction. You have five minutes to prepare to fire the orbital boosters and the shuttle engines.”

The four astronauts stared at each other in astonishment. “The station's boosters and the shuttle engines?” said Paul, thinking he must have misheard. He meant they should fire one or the other, surely. They did this about once a month, on average, to boost the space station up into a higher orbit. Harmony orbited five hundred kilometres up, but there was a tiny bit of atmosphere even that high up and it caused drag, slowing the station and dropping it into a lower orbit. If they didn't boost themselves back up, Harmony would fall out of the sky within two or three years.

“Negative, Harmony. Please prepare to fire both. You'll need them both to stabilise your orbit. I'll explain later, but first please begin the shuttle's emergency start-up procedure.”

Zhang nodded. He unclipped himself from his chair and pushed himself towards the exit hatch. Paul, meanwhile, unclipped himself from his own seat and used a handhold to pull himself across to the main systems station. He secured himself in the chair and tapped the main touchscreen to bring up the station systems overview, then selected the propulsion subsystem. A graphic popped up showing the status of the two thruster pods attached to the station. Everything was green and the fuel levels showed eighty six per cent full. The right hand side of the screen contained a long list of input boxes where the parameters of the burn could be entered. “Ready to input parameters,” he said.

“You won't need parameters,” said George in Canberra, though. “Just make sure the station's correctly aligned then fire the pods until they're empty.”

Everyone in the command module stared at each other in shock. “What the hell’s going on, George?” demanded Lauren. She'd brought the radar screen up on her display. “I don't see anything out there. Are we going to hit something?”

“What's going on?” asked Ying Yue, the botanist, looking in through the hatch from node five. “I just saw Zhang flying past like all the demons of Diyu were chasing him!”

“Our altitude shows four hundred and eighty five kilometres,” said Lauren. “That's about what it should be.”

“That's your altitude now,” said George’s voice from the speaker. “Thirty minutes ago, your altitude was two hundred and sixty kilometres!”

“That's impossible!”

“Are you sure that’s accurate?” said Paul. “It’s not connected to that GPS thing is it?”

“Negative, we confirmed your altitude with radar. We thought there must be some mistake, we've been checking and double checking. There's no mistake. Something knocked you into a more elliptical orbit with a perigee only two hundred and sixty kilometres. You need to burn everything you’ve got during the apogee period to circularise your orbit or you're coming home the hard way.”

“We did suffer a number of small impacts,” said Lauren, “but nothing that could account for such a large course deviation. An impact large enough to do that would have destroyed us!”

“We can solve the mystery later,” said George. “Right now, we've just got to save the station. How are you doing, Zhang?”

“I'll be ready to fire the shuttle’s engines in thirty seconds. I'm overriding a dozen safety systems to do this. Are you sure it’s safe?”

“Safer than not doing it. Fire as soon as you're ready.”

“How long a burn?”

“Just keep firing until you're out of fuel.”

There was a pause as the pilot digested the command. “That will leave the shuttle unable to break orbit and return to earth,” he said at last.

“Can't be helped. You'll still have the Colibri shuttle. The Jinlong can be refuelled later. Fire as soon as you're ready. That goes for you too, Paul. Fire as soon as you're ready.”

“Wilco.” said Paul, looking at the switch beside the touch screen display, one of the few physical switches the space station still had. Most of the station's controls were either touch screen or voice activated these days. Only the most important, most dangerous controls still required the physical movement of a switch, something that would be hard to do by accident. It had a guard over it for extra protection. He lifted it and put his finger on the shiny stub of metal.

Lauren, meanwhile, was activating the station's intercom. “Attention all hands,” she said. “Prepare for acceleration. Acceleration will last for twenty minutes. Secure all loose objects, close all node hatches and prepare for acceleration.” Ying Yue closed the hatch she’d just come in through, and the station shook as other hatches were closed further away.

A Chinese voice issued from a speaker. “What the hell, Lauren? I've got three vats of molten alloy in here! You'll make the metals separate! It'll be ruined!”

“Can’t be helped. Prepare for acceleration!”

“We're supposed to have a full day's warning...”

Lauren touched the screen to shut off the voice. “Okay Paul,” she said. “Go ahead.”

They were aware of a gentle acceleration even before Paul flipped the switch, though. Zhang must have ignited the shuttle's engines. The reusable space plane, docked by the nose to the station's main axis which ran through its centre of mass, was gently pushing it faster in its orbit around the earth. A moment later, the station's two built in thruster pods also fired into life, one on each side of the main axis. The station was supposed to be perfectly balanced for this, with everything, including people, arranged so that the centre of mass was perfectly positioned on the axis. There hadn't been time for that, though, and as a result the station began to slowly rotate.

The stabilising gyroscopes, located at the centre of mass, started spinning to stop the rotation and keep the station aligned. Within five minutes they were spinning much faster than they'd ever been intended to, and the steadily rising number on Lauren’s display turned yellow, then red. If they burned out, they would have no choice but to abandon the space station. Her eyes widened as the number rose higher and higher, and sweat broke out on her forehead. “Don't burn out!” she whispered under her breath. “Don't burn out!”

She reached for the intercom switch. “Bao, Benny, please go to the Icarus module, straight away please!”

“We're under acceleration!” A voice came back from the speaker.

“I know! Please go to the Icarus module!”

After several weeks of getting used to freefall, the very slight gravity caused by the firing of the thrusters would make the trip along modules and through nodes seem novel and unusual to the scandinavian and the station's third Chinese crew member, Lauren thought. She rather envied them the experience.

A moment later, though, the number under the gyroscope indicator began to fall again as the movement of the two crewmen shifted the station's centre of mass to the other side of the main axis. The off centre thrust began rotating the space station in the opposite direction and the gyroscopes countered it by gently slowing, releasing the angular momentum they'd been storing up. After a couple of minutes the number turned from red to yellow and the station commander breathed a sigh of relief. She'd be a lot happier when it went green, but yellow was definitely better than red.

Then an alarm sounded and an indictator on the main status monitor turned red. It must have been yellow for several minutes already and she’d been too preoccupied with the gyroscopes to notice. Docking port three was indicating a stress violation. That was the port the Calibri, the European shuttle, was docked at. It was on the end of one of the station’s lateral struts, perpendicular to the direction of thrust, and the acceleration was giving the shuttle weight. The shuttle was, in effect, hanging by the docking port, which had never been intended to bear that kind of load. The burn was more than half over though. If the docking clamps had held this long...

She glanced over at the display showing the fuel remaining. It was dropping with a speed she would normally have found alarming, but she suddenly found herself hoping that it would drop even faster.

“Five minutes until fuel depletion,” said Paul with a steady voice. “How we looking, George?”

“You're looking good,” the ground control's comms officer replied. “Showing some stress in the nodes, but nothing we can do about that. Our structural experts say you should hold together.”

“That's very reassuring, George. Do we have a contingency plan for if we don't?”

“We're confident that’s not going to happen, Paul. Just relax and enjoy the ride.”

Which was code for ‘If a node fails, you're all dead,’ Paul knew. The station consisted of twelve major modules and seven smaller ones connected by eight nodes, spherical units with six doors arranged at the faces of a square. They had been designed to withstand the small amount of stress caused by the firing of the orbital boosters, but with the shuttle firing as well they were currently having to carry more than twice as great a load. If the clamps holding a node to a module failed, that module would be torn loose and be left drifting alone in space. The hatches would hold the air in and save the crew, but they would be trapped inside it until the air ran out.

Also, what was left of the station would be left spinning out of control, with far more angular momentum than the gyroscopes could handle. They would soon run out of power as the solar panels no longer faced the sun, and the armoured leading face of the station would no longer be in position to sweep up the debris left in orbit during the careless, early days of space travel. The spin would also make it impossible to launch either the Calibri or any of the emergency re-entry modules. It might take hours or days, but the deaths of everyone aboard would be certain.

They tensed up anxiously as the hatch behind them creaked and groaned, therefore, and Lauren found her eyes glued to the fuel display, willing it to drop faster. The shuttle's fuel ran out first, though, and they all breathed a sigh of relief as the stress indicators dropped, one by one turning back to yellow.

Twenty seconds later the boosters fell silent as well, and the vibrations that had shaken the station for twenty minutes stopped. “Status!” said Lauren breathlessly, her eyes wide with relief.

“Green across the board,” said Paul, grinning like an idiot. “We made it! How are we, George?”

“We'll need to watch you for a while, but you're looking good. Your current altitude is four hundred and seventy two klicks. We'll send up a supply shuttle to refuel you as soon as possible.”

“Good to hear, George.” She turned to the others. “I'll be happier when we've carried out a visual check to make sure we came through it in one piece. Go take a look around, will you?”

The others nodded, unstrapped themselves from their seats and swam through the air towards the hatchway. As they went, Lauren turned her attention back to the uplink. “And now, George, why don’t you tell me what in the name of heaven in going on?”

As George's voice issued from the speaker, her eyes widened with astonishment and fear.