“No. They are not tested yet. One thing at a time. First we must check control systems are working. Then I can try drive motors before we detonate arm pyros.”
Kate waved the empty can of soup at Boris. “Want some soup?” she asked.
“Yes. Soup would be good.”
Control
The following day, Chas, Boris and Kate suited up once more and made the short dive from the galley through the storage room and moon pool up into operations. When they arrived, there were only a few inches of water covering the floor. They pulled off the scuba gear and in unspoken agreement they walked over to the portal. The wall was right there where it had been for several days. The arms holding the hab to the wall were clearly visible.
Boris checked the indicators on the gas control system panel. “Gas system is good. Reactor is providing normal power.”
“What about the drive systems?” Chas asked.
“I will check out control systems now.”
The hab’s control system consisted of an array of electric motors with caged fans. The motors mostly pointed down but were each steerable to allow thrust to be directed enough to move the hab around laterally while maintaining a fixed depth. The ops computer directed the fans as a group to maintain position based on an array of sensors. Pressure sensors provided fine depth control and sonar arrays provided a measure of distance from the wall. Optical systems complemented the sonar to provide stereoscopic visual images of the wall which were processed by the computer to provide distance and additional positional data. Maintaining a position underwater was tricky. No GPS signals made their way below the surface and there was a distinct lack of sign posts. The wall itself was largely featureless and for the bulk of the trip, the bottom was so far below them as to be of no use in determining their position. The surface barge had an audio transponder slung under it and the hab could ping it to find the distance from the surface with reasonable accuracy but even this was subject to the effects of the thermocline layer which they were now far below.
To Boris, the problem was simple: blow the pyro devices that would shear the arms holding them to the wall and add some thrust to the drives giving them a net positive upward velocity. Then wait. Eventually they would get to the surface. The power was on, the pyros were redundant designs used in space programs throughout the world and the drive systems also had some redundancy. Even with one or two motors out of commission, the computer would adjust thrust in the others to maintain attitude and velocity.
What worried him was that he had held the same feelings for the bulk of the hab’s systems before the dive and yet here they were stranded near the bottom of the Cayman trench. Most of the crew was dead, and the hab was badly damaged. As far as he could tell from the short inspection he had performed the day before, the two hab cylinders were still connected by the top tunnel, although it had pulled apart from the operations cylinder a few inches. The bottom tunnel was separated completely from the ops cylinder, which left them in a bad way mechanically. If any of the drive systems on either hab didn’t work, the computer would try to compensate, but this would put a lot of stress on what remained of the upper tunnel connection between the two cylinders. He was doubtful it would survive any torque at all. If the two cylinders separated, they would pull apart the wiring and gas line connections leaving the ops cylinder with drive motors on just three sides. He was doubtful the computer could cope with the loss of the other drives and the associated sensor systems.
He realized that someone was talking to him.
“Boris. Boris. Are you with us?” It was Kate. “Will the drives work?”
“Yes, I think that is so. Drive control system shows that motors are all ready. I can try self test cycle but this may stress upper tunnel and make more damage. So I think it best to just blow control arms and thrust up. If it works, all is good.”
“And if it doesn’t work? What then?” Chas asked. “We get out and push?”
Kate had been thinking about the ascent. “What happens if the hab comes apart Boris? We’d lose the food and water supplies and all the meds.”
“The computer may be able to compensate for the loss of the other thrusters but I am doubtful it can control the hab position as all thrusters on one side will be missing.”
“But we’d float up, right?” Chas looked nervous again. “Even if we don’t have all the motors, we still have upward thrust. It doesn’t matter if we stay in position. We still get to the surface and they will see us. Right?”
Kate agreed. “We have to try. Perhaps we should bring some of the stores over here in case we lose the other cylinder.”
They discussed this idea for a few minutes and Kate volunteered to go and get enough food, water and HPNS meds for the three of them for at least 15 days. Kate tried very hard not to think about the time it would take to get to the surface. The original plan was for three weeks of ascent so they could slowly decompress, and even then they had planned several days in relatively shallow water to complete the decompression cycle and switch back to breathing air. Doing the ascent in 15 days was the absolute fastest they could go with acceptable risk. It was quite possible they would arrive at the surface with their blood full of bubbles. If that happened, the surface crew would have three bodies to bury.
Boris said that he would run electrical continuity tests on the pryros and again on the motor controls and gas system. Chas had nothing to do, so he decided to go with Kate for the supplies.
It took Chas and Kate nearly an hour to move enough food and water into the control room. By the time they were done, they were both cold and tired. The water was gone from the control room and the air temperature was starting to return to normal now that the heating system was no longer trying to heat thousands of gallons of cold water. Boris had peeled off the upper part of his dive suit and had tied the arms together around his waist. “We are ready to depart.”
Kate and Chas nodded. Boris flipped up the pyro system switch guards and pressed the two red buttons below them. Kate looked out the portal and saw the flash from the arms just before a slight thud was felt through the hull. The drive motors came to life and added to the sounds of the hab as they pushed upwards.
The hab shifted slightly off vertical and stopped moving.
“What’s wrong?” Chas said.
Kate looked at the arms outside. The small clouds of bubbles from the pyro explosions had dissipated. Most of the arms had been separated about a foot out from the hab but one of the lower ones that connected the ops cylinder to the wall was still intact.
A groan of bending steel went through the hull and Boris reduced the upward thrust enough to keep the hab stable. “That was crew cylinder trying to leave us behind.” He said. “It seems to be stable again now”.
Kate turned from the portal. “We are still attached to the wall.”
Boris and Chas joined her at the portal. The lower arm was clearly intact.
Boris went back to the pyro control panel. “I try again” he said and pushed the pryo fire buttons. Nothing happened. He pushed them again and banged a fist on the panel.
Kate looked at him. “What now?”
“There are spare pyro cutters in a locker in the moon pool. Someone will have to attach one to the arm and we can blow it manually.”
“Chas turned towards the ladder. “Where are they? I’ll go.”
Boris explained where to find the explosive cutter. “You will plug it into the circuit at the base of the arm where the original cutter was connected. Just replace old wire with new wire. You understand?”
“Yes. Got it.”