Then the accelerometer and the tilt sensor were activated—the probe had moved. The monitoring software immediately turned on the standard camera and the top camera. The perspective had changed. Reference points were no longer where they were supposed to be. The computer automatically activated the sun seeker, a detector that looked for the sun’s disk. Position data indicated Huygens has sunk by about ten centimeters, and that the probe was still sinking. The sensors of the SSP clearly determined a salty liquid, which was lighter than water, had entered the Top Hat, the measurement instrument recess at the bottom of the lander. The values told the computer that Huygens no longer stood on firm ground. Warning signals were automatically sent to Cassini to be relayed to Earth, but the mother probe Cassini was no longer in range. Now the lander should have started to float, the camera view of the surroundings ought to have steadied, and the freshly formed lake should have come within view of the camera eyes.
Yet none of these things happened. The probe sank even further. A force must have been pulling it down, one that was stronger than its buoyancy. The main computer of the lander module was not designed for countermeasures since the probe should not really be sinking. It also had no engine to provide upward thrust. The standard camera turned blind. The top camera, which faced upward, noticed how a rising wind blew orange-colored haze above the plain of ice sand. Then it, too, slid into darkness.
The other sensors continued measuring, though the results were often contradictory. The measured curves they produced made no physical sense. It must be extremely loud here. The temperatures were 200 degrees higher than expected. The conductivity for electrical and magnetic signals changed constantly. The liquid in the Top Hat was sometimes clear and then again murky. There was no natural environment these features would apply to, except maybe volcanic vents deep in the ocean, but geological activity of this kind was not expected on Titan.
The Huygens computer did not care. It was built in the 1990s. Back then, no one thought of practical artificial intelligence. It experienced neither curiosity nor fear as it was slowly pulled into the depths of this strange moon. It administered the measurements reported by the sensors and saved them in memory units that would retain them even after a loss of energy—a function that was meant for situations in which not all measurement data could be sent to Earth in one session.
Finally, the batteries of the probe failed. Eleven hours after it had been awakened, it went to sleep forever. At least that was what the ESA and NASA teams on Earth assumed, as they celebrated the landing as a great success. On the right-hand LCD display a lonely cursor still blinked, while one sensor after the other turned itself off. Its last thought was a loop that ran with a minimum of energy from a button cell, until the electrolyte of the tiny battery froze in the cold of Titan.
December 27, 2046, Enceladus
He groaned. What is wrong with me? Marchenko looked up. There was a black area where he could not see any details. Is my helmet visor smeared? He tried to wipe the visor with his hand, but he could not move his arm. Nothing happened. His brain sent the signal, but his right arm did not move. Marchenko knew what this could mean. He was a doctor, after all.
Yet he also knew there were numerous other explanations. He tried his left arm. He noticed how the fabric of his thermal overall rubbed against the spacesuit. So his muscles were still working, but there seemed to be an obstacle. He concentrated on the command to his arm, to put all his force in it. The arm moved. By the pressure on his spacesuit, he felt that a firm mass was sliding off him.
It’s working, he thought to himself. He had wanted to say that aloud, but he could not hear anything. Then he noticed a terrible noise going through his head. It was a horrid whistling, almost like tinnitus, as well as a cacophony of various alarm signals, and then the headache, which resembled a deep humming, the only sound that appeared familiar to him.
“Marchenko here.” He tried again and concentrated on the sound of his voice, which he had known for 61 years. There it was. His voice seemed to come from a distance. It sounded hoarse, but he recognized it. He had managed to drown out the messages. A success. This was not the first time Marchenko had been in a difficult situation. He often flew into space with Russian shuttles, and he had cheated death many times. It always depended on quickly gaining a small advantage. One thing at a time.
He remembered what he wanted to do with his left arm. Wipe off the visor of my helmet. He carefully moved his elbow joint. He listened to his body. No new pain. Alright, now the shoulder. Everything fine so far. The hand appeared in his field of view. He could only see a blurry image of it. Marchenko tried to clean the visor, but the glove did not leave any visible trace. The problem must lie elsewhere. All in good time.
The alarm messages. I must not simply turn them off. He listened to them.
“Suit integrity endangered.”
“Air pressure at dangerously low level.”
“No vital signs.”
“Remaining capacity below 5 percent.”
“Core temperature has fallen below 30 degrees.”
“Survival at risk.”
The messages came from various suit systems. These messages are nonsense. Why am I thinking about them? The monitoring module is probably broken.
“Watson, analyze system,” Marchenko asked.
No reaction. Maybe I have not said it loud enough. Yet Marchenko knew this could not be true, as the AI reacted even to mumbled commands.
“Watson?”
The artificial intelligence did not answer. There could be various reasons for this. He did not want to think about them now, as some would terrify him.
“Deactivate warning messages.”
The babble of voices in his head disappeared. Marchenko saw it as a hopeful sign that normal voice commands still worked. He closed his eyes and considered his next step. Do I absolutely have to continue? What if I could just lie here, waiting to suffocate? Marchenko realized the next few hours would not be easy. If he simply gave up, he would probably spare himself pain and suffering.
From far away he could hear Francesca’s laughter. It could not be, he could not believe it, and yet he was happy about it. His eyes filled with moisture. A tear rolled down his cheek, and he could not wipe it away. Now he remembered her, the Italian pilot for whom he had performed this heroic act. It was because of her that he was lying here now. He had not been aware that he loved her. It was only when it became clear she would die without his help that he realized how much she had touched his heart.
I have to get up. I would betray Francesca if I chose the easy way out.
Just a minute later, when he tried again to move his right arm, he cursed himself for this decision. A stabbing pain moved through the right half of his upper body. He considered this a good sign, as there was no paralysis. That was something to work with. He needed to get up, but for the time being he would have to do without his right arm. It is probably a broken bone. I hope I will not have to operate on it.