“That is about as high as the software calculated our survival chances on Enceladus.”
“No matter, Watson also expects to provide more precise projections once additional information is available.”
“That is about as far as we got down here, as well. Meaning Hayato figured that out,” Martin corrected himself.
“You have a clever colleague,” Jiaying said.
“We have the analyzer system for the exterior atmosphere. We should be able to use it to find out something about the composition of the wall.”
“Good idea,” his girlfriend said. “Then why are you not already in the airlock, so you can go out to take samples?”
“Get lost,” he only half joked.
“It was nice to hear your voice, Martin. Jiaying, out.”
Ten minutes later Martin closed the hatch of the airlock behind him. Hayato had jury-rigged a sample container for him. It consisted of a can at the end of a one-meter long metal pipe. He could open and close the lid of the can with the help of a wire. The atmosphere analyzer was not an instrument they could carry around. It was attached to the outside of the lander, so it could tell the astronauts whether or not it was safe to go outside. It analyzed the ‘air’ that reached its ‘nose.’ After taking the sample, Martin would close the lid, go to the analyzer, put the can inside, and place the heating pack he brought along underneath it. Then he could only hope that enough sample material would evaporate to reach the mechanical nose.
So much for the plan. In the cabin it had sounded simple, but now Martin was afraid. While they had been discussing the situation, the wall had moved five centimeters closer. Now he stood about an arm’s length away from it. It was approximately four meters high and almost vertical. Such a structure could not have been created by wind.
He moved the sample container at the end of the pipe close to the wall, then opened its lid. His arms felt heavy, even though the tool weighed almost nothing. What if I am about to wake a sleeping giant? With a gentle motion he scraped the edge of the can across the material. Small particles fell off and dropped into the can. Martin was relieved. He repeated the procedure twice more, until he presumed he had enough material.
“I am coming back,” he said into the helmet microphone. At that moment, he noticed a movement from the corner of his eye. Was something there? He turned around. Everything looked like it had before. Was he suffering from paranoia?
“Everything okay?” radioed Hayato.
“Yes,” Martin replied.
“You jerked around so quickly I assumed you saw something.”
“No, there was nothing.”
In order to prove to himself and Hayato there was no reason for panic, Martin stepped closer to the wall. He needed to lean forward a bit, since the HUT was in his way. He moved his head as close to the material as possible. Now it was only a few millimeters away. From this distance he could see the structure of the wall. It was grayish-brown and looked as if a child had mixed water and sand and shaped the concoction into a wall by hand. Gently curved lines ran horizontally across its surface. They were not perfectly parallel, but kept approximately the same distance from each other. The child would have had to have a lot of fingers.
“What are you?” asked Martin of the wall, which certainly could not hear him. He tapped with a finger on the surface and effortlessly dug a small hole. The wall did not seem to be particularly firm. So how could it be stable?
“Martin, are you remembering the analyzer?”
“Right away.” He turned around and went to the lander. After two steps, he turned back again.
“Gotcha,” he said, and laughed in order not to have to admit being afraid.
“Martin?”
“Don’t worry, I will be there in a moment.”
Hayato had told him exactly where he would find the chromatograph—about two meters away from the exit hatch, below the stabilizer. The nose, the inlet for the gas to be analyzed, was facing downward. Martin took the package filled with radioactive plutonium oxide out of his tool bag and placed it under the can. It took a while before the decay heat could overcome the icy temperatures. He did not have to heat the can to temperatures as high as on Earth because the material only needed to reach its boiling point. After eight minutes, thin wisps came out from under the lid. Martin put the can in position and opened the lid.
“Hayato, you should be able to measure something soon,” he said into the microphone.
His fellow astronaut did not answer. Martin did not want to put Hayato under stress, but he had spent enough time out here. He glanced around carefully, but the wall had not apparently come any closer.
“Nothing new showing up,” Hayato said. “Just come back in! I think I found something much more exciting.”
January 1, 2047, Titan
Francesca looked around to orient herself and then took her first steps toward the mountains. Her effort was brief, for she lost her footing after the second step, and instead she sank deeper and deeper into the ground. Nothing pulled her besides gravity doing its work, but it was like the ground had given up any resistance. This is utterly impossible, she thought. Caught by the unexpected, she immediately noticed her consciousness was splitting into two halves. She stood beside herself and watched her leg slowly disappearing into the sand.
At the same time, panic rose inside her and discharged itself into a loud scream: “HELP!”
The Francesca standing next to her knew no one could hear her and that screaming was completely useless now. The Francesca as a panicky little girl, though, could not stop.
“HELP ME! SHIT! STOP!”
The calm Francesca watched as tears ran down the helpless girl’s cheeks. She really seemed to see herself from the outside through her fogged-up visor. Soon her body was stuck up to the middle of her thighs in what looked like common sand. While the child inside her was afraid and weeping in despair, the logical Francesca pondered how to get out of this situation. She seemed to have walked into a type of quicksand, a kind of sand that also existed on Earth. Her thoughts raced through all the facts about it. Quicksand is created by a mixture of water and sand that mostly occurs near bodies of water, and almost never in dry deserts. It had rained heavily, and while the neighboring valley had turned into a lake afterward, this one had remained dry—at least apparently. The liquid methane must have mixed with the ice grains and established the conditions for quicksand.
What did this mean for her? On Earth she would not be in great danger and would only sink up to her hips, since the water-sand mixture had a higher density than the human body. In a sense, she would be ‘swimming’ on the quicksand. On Titan, the situation might be different—the methane-ice mixture had a lower density, so she might not get enough buoyancy to ‘swim’ here. Sure enough, her body just kept sinking into the sand, and she was now submerged up to her hips. Ten seconds from now it would be too late. Francesca needed an idea immediately. What worked on Earth, staying as still as possible, would not work here. Someone, or something, needed to pull her out of the muck as quickly as possible. Her panic receded, and the child in her also wanted to find a prompt solution to her dilemma.
Then she had an idea—the oxygen tank on her back! If she opened the valve, there would be a force that might save her life in this low gravity. Francesca reached behind herself, her fingers fumbling for the valve. She could not let go of the hose because she needed the contents of the tank for her return trip. The surface of the sand was getting closer and closer. She must open the valve, now!
There was a whistling sound. Her effort was successful. A force pushed against her back at hip height. The sand moved away from her. Seemingly weightless, she floated several meters through the air.
“DAMN! DAMN! DAMN!” cried Francesca when she suddenly realized she was not able to steer her flight. She did a somersault and then fell toward the ground. Where she was about to land, smaller and larger rocks lay around and the ground appeared to be more solid. This was both good and bad news.
I hope I don’t hit one of the large rocks, she thought, and evasively moved her head sideways. Then she smashed into the ground. With limbs akimbo, she looked like a beetle that had devoured too much of its meal. Pain shot through her lower body. It must have been the rock. Thank God I did not hit it with the helmet. The fabric of the spacesuit was strong enough to withstand the shock.
“PHEW! SHIT! SHIT! SHIT!” she yelled while still lying on the ground. This was the only way for her to get over her scare. Her arm, which looked so strange lying next to her, was visibly trembling. She tried to pull it toward herself, and the muscles obeyed. No serious injuries, it seemed. Maybe some bruises. She carefully knelt and brushed off some small stones stuck to the front of her HUT. Her heart was still racing, but she was glad about it.
“Stupid tears,” Francesca said to the child inside her who wanted to start crying again. She supported herself with both hands and slowly got up. Gradually, her breathing returned to normal. Only now did she hear the whistling sound of the still-escaping oxygen. The hose! She quickly reached around to her back, grasped the valve and the adapter, connected both, and closed the valve.
A look at the arm display told her she had enough oxygen for three quarters of an hour. Francesca uttered a derisive laugh. Again! She was really getting tired of having to fight for every single breath. At least this time no one was going to kill himself for her, as no one knew what trouble she was in. She felt a certain sense of indifference rising inside her. Maybe her cortisol supply was exhausted and her body could not provide stress hormones fast enough. Three times barely getting out alive—enough for one day.
Francesca looked at the mountain range in front of her. Somewhere over there two full oxygen tanks waited for her—and she only had 45 minutes to reach them. All in good time, she decided, turning around. About fifteen meters behind her she recognized Huygens. Something seemed strange, but it took her a while before she noticed the reason—Huygens was slightly tilting to one side. A small wall of sand had formed behind the platform the probe stood on. What is that, again? Francesca shook her head. Had she gone insane, or had this moon done so? She already knew from the briefing that nothing here was the way it appeared. Still, the number of inexplicable events thus far seemed rather high to her.
She definitely should talk to the others about it, but in order to do so she would have to reach the supplies she had left behind. Francesca dragged herself away from gazing at Huygens , turned, and started to run toward the mountains.
January 1, 2047, Titan
While Martin was still peeling himself out of his suit, Hayato already held a tablet in front of his eyes. Martin pushed the display aside.
“Just a minute, Hayato, I need to get out of this.” Panting, he finally managed to get out of the lower part of the EMU as well, and now stood there in his thermal underwear. Meanwhile, Hayato was pacing up and down the lander's interior with small steps.
“Okay, show me what you’ve got.”
Without saying a word, Hayato held out the tablet to him. In the upper half Martin saw diagrams he recognized as spectra, and below it were chemical formulas.
“You know I am not a chemist. Could you explain what I’m looking at?” asked Martin.
Hayato nodded. “The spectra up here should be clear. They show what elements are present in your sample and in what percentages.”
“And this is surprising?”
“Only partially. The wall does not consist of pure water ice, as you already can determine by its color. The ice has impurities—a lot of them—as you can see by the strong lines for carbon and nitrogen or their compounds.”
Martin took a closer look at the spectra. He zoomed in on the first one at top left. He did not have a lot of experience with such diagrams, but he assumed Hayato would be right.
“Well, why is this so exciting?”
“For one thing,” Hayato began to explain, “the percentage of impurities is higher than in the pebbles and the sand lying around here everywhere. And it leads to the conclusion these could be organic molecules.”
“Astronomers have suspected for a while Titan might be covered by a thick layer of organic compounds. This does not mean there is life, if you are trying to suggest it, because Titan is much too cold.”
“True, Martin, but it piqued my curiosity. I had Watson simulate which molecular structures might create the measured percentages. In this instance, if I measure the end product of a reaction, I can draw conclusions about the chemical precursor. You can see the most likely results below the diagrams.”
Martin looked at the formulas but could not make any more sense of them than before. He returned the tablet to Hayato.
“Look here,” Hayato said, zooming in on one area. “This NH group, which is linked to the carbon by a double bond, and then the amino group. Does this look familiar to you?”
“It’s all Greek to me.”
“Greek?” Hayato gave Martin an odd look.
“It doesn’t matter. My biology courses were so long ago,” Martin said.
“Biology is actually important here,” Hayato replied. “What you are seeing here is an amino amidine. If it had oxygen and an OH group we would see an amino acid, one of the building blocks of life. However, it could hardly develop on Titan, as the necessary oxygen compounds only exist in a frozen state. There is enough nitrogen and carbon here, though. Nitrogen in the atmosphere, carbon in the methane, and numerous other compounds.”
“So what does it all mean?”
“Just a moment. The structure next to it could be called an amonopeptide, meaning it is a peptide in which the oxygen has been replaced by an NH group, namely ammonia.”
“A peptide?” Martin gave Hayato a questioning look. He was starting to feel shame for his ignorance.
“Peptides,” Hayato stressed, “are chains of amino acids.”
“I see.”
“Now, just let me finish. You probably know them under a different name. Long peptides consisting of a large number of amino acids chained together are called proteins.”
“Proteins,” Martin repeated.
Hayato nodded. “Yes. About half of the dry weight of our cells consists of proteins.”
“So this means the wall out there contains biological cells, and the only difference with ours is the fact that in them oxygen has been replaced by ammonia?”
“You could put it that way.”
“Could?”
“It is only a model, nothing more. It might be the model with the least degree of uncertainty, but there are others not much worse. I could only prove it if I took a microscope out there and observed the cells. But I do not even have a microscope here. We left that equipment on Valkyrie, which lies frozen on Enceladus.”
Martin flinched.
“This was not meant as an accusation. I know you and Francesca had other problems.”
“I...” Martin was thinking, and shook his head before starting anew. “Didn’t they say the surface of Titan was much too cold for life?”
“We do not really know what we are dealing with here,” Hayato answered. “Though if Watson’s model is correct, the low temperatures would pose no problem. Chemical reactions may run more slowly, but the molecules have time. Titan has existed for billions of years.”
“And what do they feed on?” asked Martin.
“Ethyne. You might know it as acetylene. Two carbon atoms, two hydrogen atoms.”
“Where does that come from?”
“It is constantly created in the atmosphere through solar irradiation. There is considerably less of it than should be assumed based on chemistry, a fact known for 40 years. Where does it go? The cells probably burn it together with hydrogen, converting it to methane. It has long been suspected that ethyne contributes to the creation of methane. It stands to reason the methane content in the atmosphere ought to have shrunk considerably after these millions of years. The fresh supply must be coming from somewhere.”
“Too bad all of this is only a theory
we cannot prove,” Martin said.
Hayato tapped on the screen. “There is that wall out there. It is real and can be proven. Do you really believe this is a random physical event?”
Martin wondered why the Japanese astronaut was suddenly looking at him with a frightened expression. He shook his head. Martin knew his way around physics. Yes, there were events in chaotic systems that could be mistaken for indications of life—but something like this?
“We might not have a microscope anymore,” Martin said, “but we can examine this phenomenologically. We act like researchers used to act when they discovered an unknown animal in the wilderness. 'What does this thing do when you irritate it?'”
Hayato crossed his arms in front of his chest and looked at him with half-closed eyes. “You are not serious, are you? What if it is not a harmless hippo, but rather a ruthless lion?”
“Hippos are not at all harmless, Hayato.”
“Do not try to distract me. You know what I mean.”
Martin persisted, “I am not going to just sit here and wait for what fate will bring. If we don’t know what we are facing, we cannot do anything against it if it attacks us.”
Hayato swayed his upper body. “I just do not know,” he said.
“It doesn’t matter,” Martin replied. “I am going to go out now and I will step on the lion’s tail.”
“What? You are doing what?” Hayato seemed genuinely shocked.
“Don’t worry. Just in a metaphorical sense. I am not going to touch the wall.”
“What then?”
“I am going to take the searchlight out there.”
“I understand. You want to test how the wall reacts to an influx of energy.”
“Into the potato field, out of the potato field,” Martin whispered while putting on the spacesuit. His mother used to say that in her Berlin dialect when she was annoyed about things constantly going back and forth. Martin had previously researched the origin of the expression and found it had come from Prussian soldiers who were sent into a potato field during maneuvers, to camouflage themselves, but then were chased out by the angry farmer.
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