Phobos Train
The hum, that low-frequency thrum which vibrated all the way through your boots, was the first thing you learned to trust. It signaled safety, which was necessary when you were on an eighty-thousand-kilogram hunk of metal floating down a magnetic guideway.
Brant squeezed his hand over the throttle as he brought the train to a smooth stop. The diagnostic slate glowed green. The life support system in the Stickney Crater Dome was green. He hit the button to open the doors, allowing passengers to get on and off on his way to the next location on the line.
With his minute or so of break time, he looked out at the giant shape of Mars hanging in the sky. He saw the shimmering white polar caps at its northern peak and the rusty red desert of Valles Marineris. For so many generations, people had wanted to reach the planet, to live there, to form a new civilization. But for Brant, that kind of dream was second to the need for a job so he could feed himself.
Back and forth between the massive Phobotopolis and the Gulliver Mining Complex, six times a day. He carried miners who seemed perpetually dirty, caked in regolith going and coming. The job, despite its exciting premise, quickly turned mundane. The trains traveled at two hundred kilometers an hour across the tiny moon, always giving him a view of a planet only available to the wealthy and privileged. After a few weeks of that, he was ground down harder than the rocks those miners broke.
A small vibration on his wrist silently informed him to get back to his thankless job. With a sigh, he pressed the button to close the doors. They slid back to their normal place. He turned away from his planetary view and looked down at the dashboard again. All doors properly closed and locked. Train air pressure was nominal.
He pushed the throttle forward, leaving the station exactly on time. His customers were happy with his on-time record, but for him it just became yet another part of his life that was routine.
Then one block registered yellow: “Proximity warning on kilomarker 15. Signal degraded.”
That was odd. Kilomarker 15 was just around the curve of the Stickney Crater rim. Proximity warnings weren’t uncommon. Stray chunks of ice from a venting freighter or just a maintenance drone mishap could trigger that. But the signal shouldn’t be degraded. Kilomarkers were self-contained sensor arrays buried deeply.
He grabbed the radio. “Hello Control. This is Phobos Express. I’m getting a degraded signal on Kilomarker 15. Can you pull up a diagnostic on your end?”
The reply was a burst of static. There were some garbled words that couldn’t be made out. But when the comms channel went completely silent, the silence was heavier than the vacuum outside.
He tapped twice on the top of the dashboard, triggering the gesture to open up a system terminal. He typed in the command on the virtual keyboard to directly feed the forward optical array to the screen, bypassing the automated sensor feed. A new window appeared showing the pressured track snaking across the gray desolation. Then as the stream processed further, he saw the issue.
The smooth, silver ribbon of track had been damaged. A section of pressurized tube had shattered apart. The guideway now looked like a broken bone, mangled and twisted. He could see traces of pockmarks all around, suggesting a meteorite had broken apart and had rained down on this area. One may have even damaged his comms link. Though each was small, traveling at cosmic velocities could mean a lot of damage. The metal already looked sandblasted, its silver surface pitted and scarred from the high-speed bombardment.
Then Brant looked down at the throttle, which was causing his own speed to grow. He started to run physics in his head and realized with a growing certainty that they weren’t going to have enough time to stop.
He quickly shifted to the mag-break lever and forced it all the way down. He could hear a high-frequency screech as the superconducting magnets reversed their polarity and tried to force itself against the existing momentum. He checked the speedometer and saw it slowly falling, but not fast enough.
The only other thing he could do was mashing a small button on the emergency broadcast panel, sending out a compressed burst of unencrypted data: the train ID, location, and velocity, as a MAYDAY towards Mars.
He flattened himself into his crash-gel chair and gripped the armrests tightly. He closed his eyes and thought of his sister, Sapphire, smiling at her university graduation. He was supposed to be the base one, the responsible one.
He was waiting for the final, violent stop of the train, but it didn’t come. When he suddenly felt his stomach lurch upwards, he quickly opened his eyes and looked at the screen. The lead car had just hit the buckled guideway and used it as a ramp.
The only thing he could hear was his own heart. The hum, the subliminal feeling of safety, was gone.
He forced his head to turn to the viewport. Phobos was no longer a landscape outside his window. The force holding him in his chair was not the rapid deceleration. Instead, he could see the gray sphere falling away below him.
The train’s high-speed coupled with the moon’s low escape velocity meant there wasn’t very much that had stopped them from leaving the surface entirely.
A flicker of light appeared on the internal comms panel. Then a second light. Each one was a panicked call from a passenger in another call. He could faintly hear their yelling and panic from behind him.
“Think, think. What am I supposed to do now?”
He grabbed the master override mic and spoke slowly, trying to override his own internal fears.
“Attention all passengers... This is Conductor Morris.”
He paused and forced himself to take a deep breath.
“We have experienced a major track failure. Emergency systems have engaged. Everyone should remain calm and stay in your seats. The magnetic clamps on the restraints will hold you securely. I repeat, stay in your seats.”
That was a lie, but it was all he could say. The clamps were simple electromagnets. With the primary power failing, these would be useless. But it was better than having them panic.
He killed the open channel, hoping they wouldn’t need to talk to him again. He had to turn his full attention to the red alerts flashing on his systems dashboard. The magnetic coil, the fusion core, and the intertial dampeners had all died. There was only a trickle of power coming from the solar panels lining the top of each train car. It was enough to maintain life support, for now.
The long-range comms array was offline, but that was unacceptable. He opened up the terminal again and started to cat the power schematics. When the train left the track, the primary conduits had been severed, but then what was possible with the auxiliary system?
/bin/powerbus transfer --auxillary -d TRANSMITTER -p 15
Transmitter using 15% of auxiliary power
WARNING: Life support at 85% capacity
“I can live with that,” he muttered, ignoring the warning. The color for the transmitter changed from a flashing red ton amber. It wasn’t enough. He needed to get the main dish online.
He returned to the schematics and saw that there was a manual override, a physical shunt, that was designed for this exact failure scenario. He peeled off his restraints and picked himself up. Although gravity on Phobos was weak, he found himself floating for longer than he wanted. When his boots hit the deck plating, their magnetic seals clamped him securely.
Brant found the service panel below the console and shined a small light on the plastic seal. He pulled it open and saw a tangle of fiber-optic cables and power conduits. He grabbed each one and squinted as he tried to read the labels printed on the wires.
Then he found a thick cable labeled LRCA-DIRECT. Beside it was a spring-loaded cap covering a manual port. He jerked the main power cord out of a non-essential system, the waste disposal, and slammed it into the transmitter’s direct port.
There was a chirp from above his head confirming the system had just turned back on.
He quickly stood up and felt an immediate bout of dizziness. But he was happy to see the comms panel had returned to a bright green across the board.
Brant sat back in his chair and tightened the straps. He pulled up the emergency frequency for Mars and spoke hurriedly into the microphone.
“Mayday. Mayday. This is Phobos Express. Do you copy, Mars?”
There was nothing but static.
“Mars Control. This is Phobos Express,” he tried again. “We hit a derailment on the Stickney Rim. We are now adrift. Do you copy?”
“...break... repeat... status...,” a few distorted words broke through the hiss.
“We have gone off the rails!” he burst out, his calm demeanor starting to crack. “Our train has left orbit. We’re now tumbling through space! There are three hundred souls on board!”
“Phobos Express, this is Noel,” said a new, crisp voice. “I am the mission director at Aonia Terra. We have just identified you approaching our orbit. We have just started tracking your telemetry. Please stand by for updates.”
Stand by? Brant looked out the window at the small moon now in the distance. On the other side of his cramped cabin’s viewport he could see the great red disc of Mars. Was it getting closer?
“Conductor Morris, I have just been given your orbital data,” Noel’s voice returned, still cool and calculating. “You have indeed left Phobos orbit. Your current trajectory is on a decaying, sub-orbital path which will soon collide with Aonia Terra.”
“Collision...” Brant swallowed hard.
“Your trajectory isn’t stable enough to build a rescue intercept. You will be hitting our atmosphere at twelve kilometers per second. At your current rate, atmospheric interfacing will occur in a little over one hour.”
He understood immediately. He had many memorized every manual and protocol he could get his hands on.
“We don’t have a heat shield,” he whispered bitterly.
“Correct. Your vessel is not going to survive the atmospheric friction. You’ll burn up before even colliding to the ground. You and all your passengers.”
“No. Negative. Control, there has to be a rescue vessel. An intra-Martian ferry, a mining hauler, something!” he begged.
“Conductor, I need you to listen,” Noel stated insistently. “No ship in our fleet, or any private vessel, can match your velocity and intercept you before reaching the atmospheric interface. It’d require an impossible amount of acceleration. Physically nothing can do that. We will explore other options.”
“Other options? What else is even possible?” Brant demanded angrily. “Are you going to sell popcorn and watch us turn into a meteor shower.”
Noel remained quiet. On the other side of the radio he could hear distant clicks on keyboards and murmurs that were too quiet to make out. Through the viewport, Mars loomed even larger than before. He had always wanted to go there, and yet he now realized how the monkey’s paw had curled.
“There is one chance,” Noel finally returned. “There’s a one-in-a-million shot at this. It’s high-risk. But it might be the only way for you to survive.”
“I’m listening.”
“We’ve got five atmospheric tugs sitting in our dock at Olympus Mons. They are not designed for rescue. Basically, they are just massive engines with magnetic grapples, designed to de-orbit spent cargo containers and asteroid slag for atmospheric disposal.”
“So you want to try catching us?” Brant connected the dots.
“Right,” he confirmed. “They will climb up to the mesosphere, at an altitude of seventy kilometers. They will attach magnetic grapples and use their main drives to perform a deceleration into a stable glide path.”
That was insane. It was the kind of nutty plans drawn up by a mad scientist at the end of a bar crawl in a sci-fi novel. Use space bulldozers to catch a falling needle?
“The hull isn’t designed for that kind of g-force stress. We’d be torn apart.”
“It’s not a great idea, Conductor. But it is the only one we’ve got. The only way this works is if you get your train under control. Right now it’s tumbling across all three axes. We cannot grapple a spinning target.”
“Stabilize?” but how?
“Immediately.”
Brant looked around the cabin. He hadn’t have engines or any way of controlling the train. Then a memory bubbled up. There had been a dusty footnote in a technical manual he’d read long.
Guideway Adhesion Thrusters
They were tiny puffs of cold nitrogen gas, a few of them space equidistantly along the train’s chassis, designed to make microscopic adjustments and keep the train connected to the track as it went along Phobos’s irregular gravitational shifts. But they were not designed as a full flight system.
“I have access to attitude thrusters,” he said, his voice now dry and hoarse. “They’re meant for track alignment. There’s not much propellant.”
“They will have to be enough,” Noel affirmed. “I’m going to link your console to our telemetry feed. When you receive firing solutions, execute them immediately.”
“But first I need to get them online.”
Brant looked down at his screen now displaying the schematic of his thruster control module. The power came through a dedicated bus which had been severed in the derailment. It would be impossible to reroute this from the console. There needed to be a physical patch. And the access panel was in passenger car three.
He couldn’t leave. He’d lose his connection to Noel and miss the firing solutions. He hit Car Three on the comms panel.
“This is the conductor. I need assistance. If there are any engineers or technicians in this car please respond.”
A woman’s voice came back a few seconds later. “Hello? Hello? This is Aubrina Rosesky. I’m a propulsion tech with Gulliver Mining.”
“Aubrina, thank God. I need your help. You will need to reroute some power cables so we can get the thruster control online. It’s the only thing to stop us from tumbling.”
“Can you explain what exactly is wrong?” she asked, her voice shaky but controlled.
“There’s no time to go into details. Just follow my instructions exactly. Can you do that?”
“Yes. What do I need to do?”
For the next ten minutes, his eyes darted between the schematic on his console and the low-res security feed of a terrified woman in a gray jumpsuit tentatively poking around a service panel.
“Can you see a bundle of red cables?” he asked.
“Yeah.”
“There is going to be one in there labeled TC-AUX. Find that one.”
“I see it.”
“Okay, there should be a manual socket next to it. That will have the label E-PWR. You will need to disconnect the aux cable and jam it into that socket. Be careful with it though. It might spark.”
“I got it,” she said. There was a grunt of effort. A bright flash came through the camera feed, causing the image to flicker for a few seconds until he heard her say, “It’s done.”
Brant checked the schematic again. The thruster control panel lit up with green. He had control again.
“Great job Aubrina,” he said breathlessly. “Now strap back into your seat. We’re going to be doing some maneuvers. There’ll be a lot of shaking.”
“Copy that,” she replied. “And good luck.”
“Luck has nothing to do with it,” he muttered as he shut off the radio. He turned his attention back to his primary task. His hands shook as they hovered over the console, which now displayed a 3D model of the train in space.
“We’re all set for stabilization, Noel,” Brant said into the mic. “Ready when you are.”
“Affirmative. We’ve gotten back the full firing solutions. Your first maneuver will be killing your rotation. Setup a port-side thruster to do a burst for point-two seconds. On my mark… Three… two… one… Mark.”
Brant slammed his finger down on the vertical thruster control. He felt a faint thump vibrate through the hull. Through the viewport he could see the spinning of stars slow down.
“That looked to be effective,” Noel said. “Now do a burst on the ventral thruster for point-one-five seconds. Mark.”
Brant hit the button again. A second thump reverberated through the train. This went on for forty minutes. Brant took each order from Noel and executed it as fast as he could. Bit by bit, the violent tumble slowed down and straightened out. Finally, the train was stable. Phobos remained a distant rock above them, and Mars had only become an even more terrifying floor they were still falling towards.
“Okay, Conductor, we’ve finally achieved stabilization. Stand by. The tugs are in the air now.”
“How long until...” Brant began.
“The atmospheric interface will be in five minutes,” Noel interrupted.
Brant swallowed hard. “Understood. Ready for the grapples.”
He stared out the viewport, where he noticed a faint orange flow starting to appear on the edges of the train.
“Hull temperature is exceeding nominal limits for life support,” warned his console aloud.
Brant knew that was true. He could only hope that the passengers in the other cars didn’t know that. There was nothing he could do about it.
Then he saw five small yet bright dots of light appear in the distance, growing larger by the second. Those were the tugs, he realized. Their engines were burning with ferocity as they climbed to meet them.
The orange glow of the atmosphere outside deepened, turning increasingly hellish as the the hull started to cook them from the outside in. The entire train started shaking back and forth. Brant could feel his teeth rattling and he grabbed onto the armrest to keep himself steady.
“Danger. Hull structural integrity is at 90% and falling,” his console warned.
Brant grabbed the mic and hit all every passenger channel. “Okay folks, this your conductor again. I need you all to put your heads down and brace for impact. Do not move!”
Then they were hit by the first tug. Brant’s arm was thrown forward and the air left his lungs as the train was struck by a giant hammer. The magnetic grapples screeched, a piercing metal-on-metal scream as they fought to hold the eighty-thousand-kilogram mass, and the very metal of the cockpit began to sing under the impossible stress.
His console erupted in red warnings.
“HULL INTEGRITY AT 75%”
“LIFE SUPPORT FAILURE IMMINENT IN CAR 4”
Then a second impact hit them and it was even more violent. The metal of the cockpit started groaning. Brant saw a drip of blood hit the console and he realized his nose was bleeding. The lights started flickering but it didn’t matter. He could barely think straight. The deceleration was way too intense for him to handle.
“CASCADE FAILURE. STRUCTURAL INTEGRITY AT 60%”
“We’re not going to make it,” he murmured, feeling his head spin.
Then the chaotic shuddering just... ended. The five tugs had finally arrived and synchronized their engines. The alarms shut off and the groaning stopped. Although the red glow remained, they were no longer plummeting. They could be guided safely down towards the surface.
Brant let go of the strap and fell backwards into his seat. He rubbed his shoulder and it ached fiercely. It felt like it had been pulled out of its socket. He was soaked in sweat too. He stared out at the rust-red plains of Aonia Terra coming into view. The ancient riverbeds and canyons were becoming clearer.
From the comms he could hear a new sound. The passengers were weeping with relief. There was cheering too.