“Uiiii.” He heard the voice of the Chinese astronaut in his headphones. She was breathing heavily. After a few more steps, Martin recognized the reason for it. The ring is turning very quickly now. The dynamo consisted of a magnetic coil, in which the rapid movement of the metal ring generated electricity through induction. To work efficiently, it must be as close as possible to the metal of the habitat. However, the ring was not a perfect circle. The rigid living module alternated with softer transition modules that had a smaller circumference. If Jiaying moved the dynamo too close, it would be destroyed by the enormous rotational energy. And it would probably kill the person in its immediate vicinity. If the dynamo was too far away, though, its power output would decrease dramatically.
Martin stopped. He wondered how he could help Jiaying. They would need a dummy object, something they could move closer and closer, but it shouldn’t matter if that object got destroyed. He looked around but did not find anything. From the corner of his eye he noticed the SAFER, the rocket backpack he had strapped on. There was a second SAFER on board, so this one was expendable. With one hand, Martin signaled Hayato to come over and help him take the SAFER off. Then he radioed Jiaying and explained what he was trying to do. He would kneel down at the spot where she needed to attach the dynamo. Then he would move the SAFER forward, millimeter by millimeter, and mark the front edge on the hull each time. On his tool belt he had a pen that could write in space. Jiaying lifted the dynamo and made room for him. Martin put the SAFER in its place. The habitat modules were zooming past them closer and closer. It was an eerie feeling, as everything was noiseless, and there was also no airflow such as one might expect from such a mighty carousel.
Move it one millimeter, make a marking, one more millimeter, another marking... Bam—the ring tore the SAFER from his hand. Martin’s heart was pounding. I am being carried into space, he noticed. The SAFER had briefly collided with his spacesuit and had imparted a part of its kinetic energy to him. Martin was secured by a line, so he was not in danger unless the safety line unrolled in such a way that it got into the spokes of this wheel weighing several tons. It was not designed to withstand such a weight. The SAFER was already flying through space, out of his reach. Martin felt how his momentum was driving him closer to the mighty ring. It was spooky, as everything was happening in complete silence. The rotating mass that was meant to power the life-saving dynamo would give him a push, launching him far into space. In his mind, Martin was doing a countdown. It can be only a few seconds now. Martin felt something wet on his face. It must be tears. This is not the moment I would have chosen for a farewell.
Then he noticed something pulling on his foot. Jiaying had jumped up from the spaceship. She was athletic. She caught his leg, held on to it, and pulled her body down on her safety line so Martin’s line moved out of the vicinity of the all-destructive ring.
The dynamo was working, almost optimally. Siri reported an output of 8.4 kilowatts. That was enough for the life support system to provide fresh air to the command module. It was also sufficient to operate the computer and keep a few LEDs on. It was dim, but not completely dark. They were alive, at least for the time being.
Martin watched Amy, who sat in front of her console. She seemed to be concentrating. Is she afraid? She would have to give the order to restart the engines. Everything depended on the restart being successful. Nothing really depended on the way Amy gave that order, yet it seemed to be important to her. Her behavior is irrational, Martin decided, as he had previously experienced with many people. Amy sees herself as responsible for something she cannot influence. Finally, she made a decision.
“This is the commander, please identify.”
Martin watched the others. Francesca seemed to repeat Amy’s words in a whisper. Jiaying massaged her fingers. Marchenko was whistling.
“Identified, I am listening,” Siri replied. Siri was responsible for navigation, and by definition accelerating belonged to that.
“Restart fusion drives according to standard protocol,” Amy ordered.
“Initiating restart,” the AI complied.
No one had ever tried to start a DFD out in the midst of space. Even during initial ignition in the dock, not all DFDs had started successfully. Martin heard a deep rumbling being transmitted through the structural elements. This was the body-borne sound of their spaceship. It changed its frequency, increased a bit, and then faded again.
“Restart failed.”
Amy froze on her seat. Francesca banged her fist against the wall.
“Well, that would have been too easy,” Marchenko said, trying to defuse the tension they all felt.
“Watson, system analysis,” Martin requested.
“External drive offline. Cause: Lack of fuel.”
The energy required to start up the DFD was generated by a conventional motor that burned hydrogen and oxygen, creating water. As soon as the motor was no longer needed, another module split the created water back into its components, that were then stored until the next restart. Either this had not worked, or oxygen had been lost along the way.
Martin continued, “Watson, root cause analysis.”
“This is not possible. There are missing parameters.” The AI did not know why the oxygen was not there. All of their lives depended on the answer to this problem. Martin was gradually getting tired of these situations endangering their survival. It would be about time something actually worked, he silently grumbled.
In a halting voice, Amy said, “It looks like somebody has to go outside again and check.”
“I would suggest we simply refill the oxygen tank. It doesn’t matter whether it leaks a bit. The oxygen only has to last for a few minutes,” said Marchenko, pragmatic as usual.
“Is there no alternative? Our dynamo generates electricity, so could we use that to fire up the magnetic coils of the DFD?” Jiaying asked.
“The DFD needs about 2 megawatts. We only have approximately 8 kilowatts. We could make the ring rotate as fast as we want...” For a doctor, Marchenko is also pretty good at math, Martin thought, and then turned to the AI.
“Watson, specify the required fuel.”
“The oxygen tank holds almost 200 liters. For a 100-second burn at 2 MW we need approximately 160 kilos of oxygen, which is about 140 liters in the liquid state. This amount would have to be taken from the supplies of the life support system,” the AI reported.
Martin quickly calculated this in his head. If a person consumed, as he had learned, 840 grams of oxygen a day, he or she could live almost 200 days on 160 kilos.
“Will that endanger our mission, Watson?”
It is a useless question. Martin knew this. They would have to refill their oxygen supplies on Enceladus anyway. Watson still gave an answer.
“Our stay on Enceladus can only last five months, instead of six months.”
“This is acceptable,” Amy said. “Who is going to refill the container?”
Marchenko spoke up. “From a medical perspective, Jiaying, Hayato, and Martin should not go outside again so soon. That only leaves Francesca and me.”
“It is not as simple as it was before. Only the command module is under normal pressure.”
“Correct, Amy. We should get the neighboring module up to the pressure normally used in the airlock—to get us adapted.”
“But the spacesuits are still in the airlock” The commander said, shaking her head.
“That is a problem,” Marchenko said, “though if we get all the rooms between here and the airlock to one-twentieth of a bar of pressure, our cell walls should withstand the interior pressure. We could run to the airlock, close the inside hatch, and increase the pressure to half of the terrestrial level. Would that be possible within a minute?”
No one answered.
“Watson?” Amy asked.
“Yes, that is a realistic scenario. There is a probability of 85 percent that you will reach the airlock without losing consciousness. Although I have to point out that you should no
t waste much time before starting. Getting captured into an orbit around Saturn will become impossible if the drives won’t restart and provide deceleration within 120 minutes.”
If they did not hurry, they would overshoot Saturn, and there would be no return. Martin felt the coldness of space creeping up his spine. He saw that the others had similar feelings.
A final farewell. Francesca and Marchenko were a good match. Both had pragmatic, take charge, low drama personalities. Martin no longer noticed the tension that had existed between them over the question of whether or not to break off the mission. They closed the hatch to the command module and did their job. They ran through a near vacuum that did not kill them because they had exhaled beforehand. He fervently hoped they would reach their goal in time. After the drives were restarted, everything would once again be like it was before. No, it will not be like before, and that feels good. He looked at Jiaying, who did not notice his gaze. He realized, I have not even thanked her yet. He had very good reason to thank her. It has become clear to me how precious my life is—and so is Jiaying’s.
“Ready... set... go.” Marchenko had given the command. He let Francesca go first. She was younger and faster. She might gain them decisive seconds if she pressed the button first. The system needed a moment to blow fresh air into the airlock. Martin listened intently, but he could not hear anything. There was no gasping and groaning. Both of them had exhaled before entering the low-pressure area in order to protect their lungs. There was no heartbeat. The microphones in the uniforms weren’t sensitive enough for that.
“Airlock closed,” Watson reported.
“Commander to EVA team, what is your status?”
Francesca gasped for air. “Reached airlock. Marchenko... unconscious. What do his biosensors say?” Her voice sounded worried.
Amy replied, “His circulation is stable… Maybe he is in shock. We will see. He is alive, though.”
“I am going to put his EMU on him and then go outside,” Francesca said.
No one contradicted her because it was the logical solution. Francesca had to fulfill the task on her own. Martin saw the commander knead her hands. For a while, only breathing could be heard from the airlock. He imagined Francesca putting the spacesuit on the unconscious man. That wouldn’t be easy.
“I’m finished. I am closing Marchenko’s helmet now. He is breathing.”
“Excellent, Francesca,” Amy said.
“Start with the egress.”
“Siri, we need all available cameras.”
“Confirming, commander. Approximately 85 percent of the work area of astronaut Rossi can be viewed by cameras. Starting transmission.”
“Show it on the fog display,” Amy directed.
Above the conference table, a figure in a spacesuit suddenly appeared, walking among the stars. The cameras were aiming from below. The four astronauts in the command module saw Francesca make her way across the hull of the spaceship. First she had to get an oxygen container from storage. Then she had to fill the container from the inlet port of the life support system. The port was intended to fill the internal tanks, but Watson could reverse the flow direction of the valves. Afterward, Francesca moved to the oxygen tank of the motor near the drive module. That was about fifty steps, including crossing the chasm that had caused Martin such problems. She emptied the container and started on her way back.
The oxygen tank contained 20 kilograms. Francesca therefore must perform the procedure eight times. During the chore, the vacuum had advantages and disadvantages; there was no fire hazard, but splashes of liquid oxygen could damage Francesca’s spacesuit. Thus she would still have to be very careful when transferring the oxygen.
Martin calculated she would need twelve minutes for each filling. That means 96 minutes before the motor is operational again. Then they could start one drive after the other. For the first one, the motor had to provide the necessary energy for 100 seconds. Afterward, the running DFD generated the starting current for the next drive. As each drive module required about two minutes, this would take another 16 minutes. Before, Francesca had needed one minute to reach the airlock, and there she had invested ten minutes in putting the EMU on Marchenko. 96 plus 16 plus 11 went through Martin’s head. Have I forgotten anything? Right, the time from the exit to the storage and then to the filling port of the life support system, maybe two minutes. A total of 125 minutes, five more than Watson has mentioned until the drives have to be restarted. Okay, the braking effect will already start once the first one is ignited. On the other hand, they will have to wait until Francesca is back in the airlock since the increasing acceleration will complicate her return.
He did not tell the others about his calculations because it was only a rough estimate. Maybe Francesca will be considerably faster than expected, as the oxygen tank does not weigh anything. Martin noticed his knees were starting to shake. Amy sat with her legs spread to gain a firmer hold. Hayato was scribbling something into a notebook. Martin could not exactly see what it was. Perhaps formulas or Japanese characters maybe. Is he writing a farewell message in his diary? Jiaying had placed her chair with the seatback forward and sat in it. This allowed her to lean back as much as she wanted since her position stayed the same in zero gravity. She was almost horizontal and had her eyes closed.
“Is there anything we can do?” Hayato asked as he put his pen aside.
“No,” Amy gasped. There was nothing else to say.
On the glittering display they saw Francesca struggling with the port of the life support system. The last time its cap had been opened was in Earth orbit. If everything had gone according to plan, it would have remained closed until their return. No one had expected a single astronaut would have to unscrew it. The pilot first tried to use her hands, then special pliers from her tool belt. Unfortunately, she was not strong enough and needed more leverage. The camera followed her as she stood up and looked around. Martin called up a diagram of the ship on his tablet. About three meters from Francesca’s position there should be a dish antenna supported by strong metal struts. These were not simple pipes, but actuators that could be remote-controlled to aim the dish toward its goal, Earth. He wanted to mention this to Francesca, but she seemed to have already discovered this option. The camera showed her unscrewing one of the struts. Luckily, the struts were not welded to the hull or the antenna dish. Before they could send any more messages to Earth, they would have to repair the antenna, but that was not important now.
The metal piece was about a meter long and sturdy enough to give Francesca more leverage. Via the helmet radio, all of them heard Francesca trying with renewed effort.
“Ha,” she finally said as the cap started to move. Martin looked at the time. Another ten minutes has passed. My new estimate: 135. He wondered, Should I let Watson display a countdown? However, how will this number help the others? Time passed, and they could not stop it.
Soon it became clear Martin’s calculations had been too optimistic. The portable container might not weigh anything, but its inertia still impeded Francesca. She needed almost five minutes in one direction, instead of the three he had assumed, so that made another 16 minutes, a total of 167. At least the cap of the oxygen tank at the motor could be opened easily. Was that the reason the tank was empty? That would be a blessing in disguise, as the newly filled oxygen would be leaking out if the tank itself was damaged. If there was only a microscopic crack, they might have enough time, though. They needed the motor to run at full power for 100 seconds, no more.
Francesca was on her way back. Martin watched her movements. He noticed the pilot had a specific talent—she had found an optimal rhythm. She is also probably a good dancer. The idea brought him back into a part of his past that he had not wanted to acknowledge for a long time, to a former life in which he floated across the dance floor with his girlfriend. She had talked him into taking a dancing class, even though he was generally more of a couch potato, but surprisingly he had really enjoyed it.
He looke
d at his watch. Four minutes. Francesca is getting faster—a total of 152 minutes, if everything goes well. His knees were trembling.
Thirty minutes later, everything was still proceeding smoothly. Francesca now averaged four minutes for each leg of the way, 14 minutes per filling instead of 12. Another 122 minutes until drive ignition. Watson wants to decelerate no longer than 90 minutes from now.
A moaning sound came from the loudspeaker. Eight eyes looked at Francesca’s image on the fog display, but she was moving across the hull in a routine fashion.
“Marchenko?”
“Reporting for duty, Commander,” the doctor replied.
“Great!” Martin could see Amy’s eyes sparkle. She updated him as fast as she could. Francesca was on the third round of filling the tank, carrying a full container to the motor. Five more rounds remained. First Marchenko would have to get an oxygen container. Then he could take on at least two rounds of filling. He was new to it, and no athlete, but it would not take him longer than Francesca’s three rounds. That will save 28 minutes. We are getting closer to Watson’s countdown.
Marchenko quickly understood what needed to be done. Time is lost when the two astronauts encounter each other, particularly if it happens near one of the filling points. Amy realized it the same moment as Martin did.
“Commander to Marchenko. Always give Francesca right of way when she is near.”
Since he only had to do two rounds, Marchenko had more time than the pilot. Hayato started to rap his knuckles against the tabletop. I cannot blame him for doing that, Martin thought. Jiaying still floated, leaning back with closed eyes. I wonder where she might be right now. I would like to escape from reality, too. But Martin chose not to visualize the dance scenes again.
“Last round,” Francesca announced. Martin could not hear any relief in her voice.
“Watson, briefly describe consequences of starting engines with astronauts in EVA.” Amy must have watched the clock as carefully as Martin had.
Ice Moon 1 The Enceladus Mission Page 17