Below Mercury (29 page)
These gases had to be extracted, along with water vapour, before the air could be recirculated. At the top of the mine’s oversized return shaft, which doubled as a buffer air reservoir, the cooled air was fed through a specialised part of the fuel refinery to extract the unwanted gases. Oxygen and nitrogen, extracted from the ice, were added to the air to correct the gas mix, before the air was returned via a long airway that led under the crater floor, back up to the main ventilation fans near the accommodation levels.
As the mine expanded, a pair of sub-main shafts had been sunk deeper into the crater. Starting from shaft heads cut into the rock 600 metres below them, the sub-mains penetrated a further two kilometres down towards Mercury’s iron core.
There the shafts emerged at the level of the metal-rich orebodies far below the crater, whose molten tendrils had solidified in the fractured rock when the crater had been formed in that titanic impact three billion years ago. In the deep stopes two-and-a-half kilometres underground, mining robots worked to break out the metal-bearing rock and load it onto the conveyors, at the start of its long journey back to the smelting plant on the surface.
The four of them moved away from the shaft entrance, looking for anything that would tell them more about the fate of the mine personnel.
Matt called Bergman over to the control panel for the hoist, and pointed to the status display. There was power to the hoist, as they had expected, and the double-decker cage was at the bottom of the main shaft, at the 400 level. The operator’s key was still in the console.
‘Think we should raise it?’ Matt asked.
‘Well, our mission’s going to be pretty short if it won’t come up. Let’s give it a try.’
Matt set the controls to bring the cage to the surface, held the interlock handle closed, and turned the control handle to start the hoist.
A shrill bell rang twice, and above them, in the unseen hoist motor chamber, the brake blocks shrieked as they were pulled off the hoist sheaves. The red lighting dimmed slightly as the motors sucked current, and behind the grille, the wire ropes began to move. The heavy counterweight fell past in its guide ropes, on its journey to the bottom of the shaft.
A faint thrumming came through the rock as the hoist picked up speed, and the wire ropes quickened to a glistening, metallic blur.
Two minutes later, the hum of the hoist motor started to slow, and a faint singing sound came from the guide ropes.
‘It’s here,’ Elliott said, and stood back, as the cage lifted up into sight behind the wire grille. The cage shook slightly as it slid into a set of four vertical guide rails, which steered it into the correct position in the shaft station. There was a squeal of seized guide wheels, a slowing of motion, then a thunk of heavy-duty brakes gripping the guide rails. The lights brightened as the hoist motor halted.
Both safety gates in the mesh moved aside, and the cage doors slid upwards, revealing the battered interiors. The floor of the lowest cage was fitted with a short section of rail track, to allow mine cars loaded with materials to be rolled aboard.
‘Okay, so the hoist works. What now?’ Elliott asked, ‘Are we going to go down into the mine, or continue with the plan?’
‘We stay on plan,’ Bergman said in an unhurried way, glancing at his watch. ‘We can’t afford to get distracted here. We’ve proved the hoist works, so we know we can come back here later, after we’ve got you guys to the service raise. Okay?’
The three of them nodded.
‘Right, I’m going to send the twelve hundred hours report, then we’ll get going again. Do you want to check out that loco and see if we can use it?’
Matt looked dubious, but he went over to the locomotive while Bergman tried to raise Clare’s team on the comlink.
Matt sat down on the locomotive’s dusty seat and wiped the control panel clean. He found the master switch and switched the power on, but there was no response from the controls; the batteries were completely dead. He looked back at Bergman, who was frowning at the comlink.
‘Any luck?’
Bergman shook his head. ‘They must be out of coverage. I’ll send a text letting them know where we are.’ He tapped at the keypad of the comlink for a few moments, and waited while the message went, then snapped the comlink shut. ‘Okay, guys, let’s move it.’
Bergman and Elliott set off down the continuation of the passage into the mountain, and disappeared from view. The robot lumbered round, preparing to follow. Abrams turned round, expecting Matt to be just behind him, but Matt was still standing there in the shaft station, looking at the wall, a stricken expression on his face.
‘What is it?’ Abrams asked, then saw it as well, and stopped.
In an centuries-old practice that had not been bettered for simplicity and safety, every person going down a mineshaft was issued with a pair of identical, numbered metal tags before they went down the shaft at the start of every shift. One tag had to be surrendered in order to board the cage going down, while the matching tag was collected at the end of the shift. This simple system showed exactly who was down the shaft at any moment, and a check that they had all returned safely.
On the wall, in neat rows on hooks, over a hundred unclaimed metal tags hung, covered in dust.
It was a poignant sight, and it was many long moments before Matt and Abrams could bring themselves to turn away, and follow the others down the passage.
After another 300 metres of level progress, the passage emerged in another shaft station, built similar to the first, but with only one level for loading and offloading. The place seemed to have been abandoned; it had a disused air about it, and damage here seemed to be worse.
Part of the roof near the shaft head had fallen in, covering the chamber with piles of rock and dust. A mining robot lay under the rubble, its upper body buried by the roof fall.
Bergman and Matt stared up at the roof. Lumps of loose rock still adhered to the roof, threatening to come down at the slightest disturbance.
‘What is this place?’ Abrams asked.
‘Secondary intake shaft,’ Matt answered. ‘It was meant to assist the ventilation in the mine, but it never got finished. Keep to this side of the chamber – that roof’s unstable.’
‘Do you think this hoist will still work?’
‘I don’t know,’ Matt said, glancing up at the roof again, ‘but I don’t think it would be safe to try to find out. We’ve got one working hoist – that’s enough. I suggest we leave this place alone.’
Nobody disagreed, and they set off again, along a much narrower passage that continued into the mountain. The rail track ran along the centre, and there was less room to either side. The robot could no longer walk to one side, and instead straddled the narrow track with its rolling gait.
The air was close and still; evidently there was little natural circulation here. The passage, which had been flat, started to climb steeply upwards. Despite the low gravity, they were soon breathing heavily from the exertion and the heavy, stagnant air.
‘How much further is it?’ Abrams gasped after they had covered about five hundred metres, and had stopped for a brief rest.
‘A long way still,’ Matt answered between breaths. ‘This passage is nearly two kilometres long. We’ll just have to do it in stages.’
They resumed their journey once they had rested, and had got their breath back. Ahead, there was a section of the passage where the emergency lighting had failed, and the team plunged into darkness. In the distance, a single red light burned, and drew closer as they followed the passage upwards. They were already higher than the accommodation levels; the passage was taking them up high into the mountain’s heart.
They came to the red emergency light. The lighting seemed to be working from here on upwards; further red lights led into the distance, but it was hard to tell how much further there was to go. The lights came and went, in a seemingly interminable sequence, as they continued their slow journey upwards.
They stopped to rest twice more on the long climb, and Bergman was just about to call another halt, when the lights ahead came to an end. The passage opened up into a shaft station, smaller than the two they had encountered earlier. There was a faint breeze at their backs, and the air seemed less close and heavy. They stood in the red light of the shaft station, getting their breath back.
The shaft opening was on the left here instead of on the right as in the other stations. Compared to the other two stations, this one had almost no trace of any damage. There was a thin coating of dust in the chamber and some scattered paper, but that was it; the force of the escaping air had been less here than in the main airways.
The safety gate in the grille stood wide open, and beyond them, the cage waited. The raise went straight up into the mountain, to emerge two kilometres above them, in its high eyrie on the mountaintop. From there, a walkway wound up into the peaks, weaving its way through a high pass, until at last it emerged in the perpetual sunlight at a peak on the crater ramparts, nearly four kilometres above the surface of the ice field.
Running down the circular shaft of the raise, away from the guide ropes, were the heavy power cables and communications links from the solar power array and antennas on the mountain peak. The raise was narrower than the main shafts of the mine; it had been bored to allow the installation and maintenance of the equipment on the otherwise inaccessible mountaintop, and once the equipment had been installed, only occasional visits were needed.
‘Seems like it’s operational,’ Bergman commented, examining the hoist control panel. ‘I’m going to give it a try.’ He thumbed a few switches and operated the interlock and control handles. The cage door slid down, and the safety gate closed with a shriek of metal on guides. There was the harsh double-ring of the bell, and the cage started to move upwards. Bergman let it run for a few seconds, then halted it and brought it back down.
‘Okay guys, this is where we load you up.’ He opened the gates and indicated the waiting cage.
Elliott ordered Bob Five forward, and once inside, the robot turned round to face them, still carrying the six air cylinders. Abrams took the rucksacks containing the radio equipment from Matt and Bergman, and followed Elliott aboard the cage.
‘You guys clear on what you need to do?’ Bergman asked.
Elliott and Abrams nodded.
‘Okay. I’ve set the hoist to Cage Control, so the cage will stay at the top station until you’re ready to return. Good luck.’
‘See you in the control centre later,’ Abrams said, as the door closed over them and the safety gate screeched shut. The bell rang twice, and the cage started to move.
‘Bye,’ called Elliott from high above, and then the car was gone, climbing up into the long raise on its journey up inside the mountain. The wire ropes quivered slightly from the cage’s motion, but it was otherwise silent in the chamber; the hoist motor was thousands of metres above them, at the top of the raise.
Bergman stood by the gate and craned upwards. High above him, he could see the dwindling light from their companions’ flashlights, as the cage disappeared up into the mountain. A creak ran through the guide ropes.
‘Wonder how long it’ll take them?’ he said.
‘Well, if the other hoist’s anything to go by, they’re going to be a while,’ Matt responded.
‘Yeah. Well, we can’t do anything more to help them now. Shall we go back and take a look at the main shaft?’
‘I suppose we’d better.’ Matt’s voice was resigned.
‘Look, I know we’ve drawn the short straw, but we’ve got a job to do. I don’t like it any better than you do.’
‘I know. I just don’t like the idea of going down the mine, that’s all. Guess I’ve got a bad feeling about what we’re going to find.’
‘Yeah, you and me both,’ Bergman sighed, looking down the passage that led back to the mine. He clicked his flashlight back on. ‘Come on, let’s get it over and done with.’
They set off back down the long, sloping passage, their flashlight beams illuminating the red-lit walls in shifting ovals of stark whites and greys. Their silhouetted figures dwindled against the lights as they walked, until they were lost to view.
Clare Foster and Steve Wilson walked in silence down the gentle grade of the main return airway.
It had been half an hour since they had parted from the others at the bottom of the fire stairs, and they were already far out under the crater floor. The airway ran from underneath the accommodation levels, out under the crater to the refinery complex and shuttle silos, a kilometre from the entrance to the mine.