The Titan Probe
Hard Science Fiction
Brandon Q. Morris
Contents
Part 1: The Awakening
Part 2: Return
Author's Note
The Guided Tour of Titan
Glossary of Acronyms
Metric to English Conversions
Part 1: The Awakening
January 14, 2005, Titan
Huygens awoke at 04:41 a.m. All three preprogrammed timers punctually activated the probe named after the Dutch astronomer Christiaan Huygens. Its main computer ran the test program. The sensors were in working order. Now the scientific instruments were triggered, step by step. First diagnosis—it was in free fall. Everything was going according to plan.
Twenty days ago, a spring mechanism had separated it from the Cassini probe, its ride that had brought it to the ringed planet Saturn over the course of seven years—almost two billion kilometers, though Huygens had noticed little about this long journey. Data packages had been sent from Earth on 16 occasions to run health checks.
Huygens was racing toward Titan at 17 times the speed of sound. No piece of technology made by humans had yet landed on this moon, which resembled the moon of Earth like no other object in the solar system, yet was also so very different from it. The control software of Huygens was prepared for all kinds of surprises, because its programmers did not know much about Titan when the probe was launched.
The countdown continued. The probe was still in freefall toward its destination, which was located somewhere south of the equator. Four hours had gone by when the sensors reported the first particles of the atmosphere hitting its heat shield. The air rapidly became denser. Friction heated the cone-shaped heat shield at its bottom, and at the same time it decelerated the probe, within four minutes, to just above the speed of sound on earth. The pressure sensors transmitted a signal to the main computer. A charge was triggered, and the controlled explosion released the main parachute. At first, Huygens fell blindly, but 30 seconds later the probe moved slowly enough to blast off the no-longer-needed heat shield. Now the instruments started their work, until a warning message reached the computer—one of the radio modules had failed because a person on Earth had forgotten to send the activation command. There was no time for calling back. On Earth, it would be several hours before anyone noticed what had happened. The automatic system decided to continue its mission.
The probe was 150 kilometers above the surface. The moon now covered most of its field of view. A light brown haze impeded its vision. A fierce east wind, many times stronger than winds of hurricane strength on Earth, hit the parachute and pulled it along. At an altitude of 100 kilometers, Huygens separated its main parachute and deployed the smaller stabilizing chute, as the atmosphere was now so dense the smaller one would adequately decelerate the probe. As Huygens descended, the wind gradually faded away. The haze still impeded the view downward, but the scene became clearer with each passing second. The probe was aiming for a dark brown valley located inside a lighter-colored hilly area. In its direction of travel, the instruments discovered two dark, parallel lines, like dunes on Earth, though probably many times bigger.
There was another layer of haze below Huygens. It was lit by the light of the sun, and almost looked like a fancy bed sheet covering the short mountains of Titan. The disk of the sun appeared reddish, and small—about the size of a car headlight at a distance of 150 meters. The Huygens Atmospheric Structure Instrument (HASI) analyzed the air and discovered a lot of nitrogen, some methane, and a little bit of hydrogen.
The cameras of the Descent Imager / Spectral Radiometer (DISR) saw the mountains grow below the probe as it approached its destination valley. They appeared cragged, like high mountains on Earth. Measurements showed, however, that they only rose a few hundred meters above their surroundings. There was no snow, but the mountains were made of ice. Creeks had carved themselves into their slopes, just like the meltwater rivers of the European Alps.
At an altitude of eight kilometers, the direction of the wind changed. Now it drove the chute westward. Huygens could not intervene. At 11:38 hours, the probe landed on the surface of Titan with a speed of 18 kilometers per hour. Even though it weighed almost 300 kilograms, it bounced off the surface several times due to the moon’s low gravity. Its cameras looked around. Huygens had landed in an apparently dry area that resembled a rocky desert on Earth. Around it were several fragments that looked like boulders, randomly placed as if scattered by a bored giant. Otherwise, the ground appeared to be covered by sand. Yet Huygens was not on Earth. It was cold here, very cold—minus 180 degrees. During its descent, the probe had been heated by friction, so now wisps of fog, evaporated methane, rose from the ground. The boulders were not made of granite or sandstone but of ice, just like the grains of sand on which Huygens had landed. The gas chromatograph proved the ice was impure and contained many organic compounds.
Huygens had a mission. If a probe was capable of being happy, it would be happy now. Its instruments recorded the new world around it and transmitted the results of the measurements to Cassini, just as planned.
Then, 72 minutes after touchdown, the mother probe Cassini, which sent off Huygens days ago, disappeared behind the horizon. The landing module was now completely alone. Radio telescopes on Earth would continue to receive its carrier signal for a while longer, but it could neither send nor receive data now. Huygens’ main computer was programmed to continue its monitoring routine until the batteries were completely exhausted. A quarter of an hour later, the heat sensor recorded new data. The sensor consisted of a platinum wire; it sensed a change of electrical resistance. This meant the temperature at the base of Huygens must have increased.
The computer was not supposed to interpret this event. However, its programming was flexible enough to react to unexpected occurrences. The software increased the sensitivity of other sensors in the SSP, or Surface Science Package. The Acoustic Properties Instrument (API) measured how fast sound was propagating. The Refractive Index Sensor (REF) determined the refractive index of light. The Fluid Permittivity Sensor (PER) examined the propagation of magnetic fields. All instruments agreed the properties of the soil must have changed. Had the heat on the underside of Huygens caused the ice crystals underneath it to melt? That should not worry the lander. It was able to float, as its designers wanted to be prepared for an ocean landing.
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. T
hen 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.
Marchenko slowly put his weight on his left arm and then gradually raised his torso. Now he saw the sky was not completely black. Above him was a kind of dark hole, an oval with pointed edges surrounded by a silvery, shiny rim. I definitely have to clean the helmet visor because the image is still blurred. Moaning and groaning, Marchenko managed to sit himself up. Now he could better separate the sounds in his head. There was his own breathing. The whistling had disappeared, and the humming of the headache had retreated into his temples. Therefore, the slight murmur of the air conditioning and the hissing of the fan could be heard clearly. Cool oxygen was blowing against his face. He did not yet want to look at the usage indicator, as he refused to know how much time he had left.
Marchenko looked around, as much as that was possible in the stiff spacesuit. It was not by chance or accident that he was inside a crevasse. He had deliberately aimed for it, with the last bit of gas remaining in the SAFER backpack, so that he would not bounce off the surface of Enceladus during the expected hard landing, and drift back into space. That was the only way he could be sure the extra oxygen tanks would reach Francesca and Martin.
He reached behind himself with his left hand and touched the ground. There is nothing there. They must have picked up the oxygen tanks. I hope my action has not been in vain. I do not mind that they have left me here. They probably thought I was dead.
“This is Marchenko, come in,” he said over the radio, though he did not really hope for an answer. The radio module must be broken, because otherwise the suit would have automatically sent a distress call with his vital signs long ago. Yet I still have to try it. The devil is in the details. Maybe there is only a problem with the data circuit.
The background noise did not change. He knocked against the lower part of the helmet with his glove. He could clearly hear the thumping sound. Marchenko looked at his lower body. He moved his legs. They reacted obediently and registered no pain. Ice dust and small chunks covered his suit. He shook them off. It is time to stand up.
He leaned on his left arm and turned his body in that direction. Like an old man, he thought, I am standing up like an old man. He got onto his knees. The whole right side of his upper body complained with a nagging pain. But it was bearable—he had experienced worse agony before. He hoped this was only a sprain. He was on his knees now and first raised his upper body. Then it was
time for his right leg. He was grateful his body weighed so little due to the low gravity on Enceladus. The left arm gave a little push, and then he managed to reach vertical.
Marchenko wobbled a moment, and then he stood steadily. He felt drops of sweat running down his forehead. The fan ran faster. His heart was racing. He did not yet know why he had survived the crash, but that was not important now. He was alive, and the rest would turn out all right. He gazed upward toward the black sky. That was the next step. He had to get out of here. The crevasse should be only a few meters deep, he told himself. What did he need his right arm for? He could handle the two kilograms his suit weighed here with his left arm. Marchenko clenched his teeth. He was going to make it, because he owed it to Francesca.
December 27, 2046, Earth
“Bob, the next school class is already on the way.” Robert Millikan shook his head and sighed. He knew that Mary, the secretary, could not see his gesture, but he did not care. He ought to have time for breakfast, a muffin he had bought at the snack machine in the lobby. He removed a piece of paper and bit into the muffin. It was dry. He swallowed the bite and grimaced.
This happened more and more frequently. Fewer and fewer visitors were coming, so the vending machine was restocked more and more infrequently. He had considered bringing his breakfast from home, but that would mean shopping after work instead of having time to read. After his wife finally moved out a few years ago, he had been able to completely focus on his books.
“Robert, the teacher is really getting on my nerves.” He noticed a tinge of panic in the voice coming from the loudspeaker in the corner of the room. That's typical for Mary. She gets flustered over the most trivial things. Robert Millikan, 68, swallowed once again, crumpled up the rest of the wrapper, and tossed it into the wastebasket from three meters away. A hit! He stood up and cheered. The day had started with a good sign, like practically every day in the last few years. When was the last time he had missed a shot? It must have been ages ago—maybe back when he had come to the observatory, fresh from the university, curious about a future full of discoveries.
The Titan Probe Page 1