by Olga Werby
“Me too,” he said. “We should have sent the drone first.”
“Ian insisted, didn’t he?” Vars tried to remember again whose idea it had been to send Alice.
“I’m not sure. It could have been Liut. Does it matter?”
“I think Ian is compromised.”
Ben nodded. “But aren’t we all?”
But some more than others, Vars thought.
She noticed that Ben was rubbing his implant site, an unconscious gesture. All the others did the same—they rubbed, scratched, or just made micro gestures like a brief twitch or a flick of a finger. The scars were a constant source of irritation, but Vars suspected the touches were more related to habit. The scientists had relied on their D-tats for years, and the loss was difficult to overcome. Surprisingly, among Liut’s crew, he was the only one who showed any signs of D-tats bereavement. With others, there were no hints of overcoming cyberhumatics privation. Could the people Liut picked for this mission never been implanted? Was it another clue? And if so, what did that mean?
The door slid open again, and Trish walked in. “Mind?” she said.
Vars suppressed a sigh and slid over a bit, making room on the bed for the woman to sit. Ben moved to the only chair.
“I didn’t really like Alice when I met her,” Trish said without preamble. “She struck me as too stuck up, too good for us. She acted like she always knew better than everyone else. And the worst part was, she did know better than us. She was always right. It was insufferable.”
“We’ll all miss her,” Ben said. “She taught me the current thinking on panspermia, you know. Apparently the Seeds in Australia are all over that—”
“Why are you here, Trish?” Vars asked, interrupting Ben’s nervous chattering. She didn’t want to talk about Alice; she didn’t even want to think of Alice. She wanted to rest...needed to. “Both of you. Why are you here? In my room?”
“It seemed like the place to be,” Trish said. “Ben just got here first. Grief is easier to bear when the load is shared.” She scooted over, pressing Vars into the wall, and patted a spot on the other side of her. “Come back, Ben. Join us.”
To Vars’s surprise, Ben returned to sit on the bed next to the two of them. It was uncomfortably cozy now.
“I will really miss Alice,” Trish said, “whether she’s truly dead or…something else.”
Vars hadn’t allowed herself to even think in that direction, and here Trish just blurted it out.
“She’s dead to us,” Ben said. “That’s all that really matters. She’s gone, and we need her.”
“And I don’t trust Ian,” said Trish. At least they agreed on that. “Or Liut.”
“Or the twins,” Ben added.
“The list is getting long,” Trish agreed. “But you’re fully human, Vars, and…I guess maybe that’s why we’re both here. You’re a pure Seed. A link to our humanity. When in doubt…” She took Vars’s hand and held it. It wasn’t unpleasant, just unexpected, unaccustomed, different. “I want us to work together,” she said. “I know you’ve been working with Ben. And I want in.” She squeezed Vars’s hand lightly. “Ben has never been my type,” she added quietly. “And you’ve never declared yourself.”
Vars jerked her hand out of Trish’s and wrapped her arms around herself. She wasn’t following. Was Trish…propositioning her? Here? Now?
Seeing Vars’s reaction, the woman said, “Relax. Who has the energy for that?” She looked embarrassed. “I just feel so...so alone,” she added in almost inaudible whisper.
“Why don’t you stop freaking out our host and tell her what Alice taught you about the biological quirks of life in our solar system?” Ben said. “Vars is all about evolution and historical trends, but she’s all soft science. She’s not even a biologist. And Alice is no longer here to fill her in.”
Vars didn’t react to the slight—she’d heard worse from Ben, especially in the early days. And besides, she wasn’t feeling much of anything right now. Just tired. Still, she missed the first few words Trish said.
“—basic organic chemistry. Life uses organic molecules to pass information from one generation to the next,” Trish started. “I’m sure you’ve heard of DNA—” Vars groaned and Trish smiled. “Of course you have. Even a soft scientist like you—”
“Trish, please?” Vars asked. It just wasn’t the time. She didn’t have the energy to deal the woman’s smugness.
“Right then,” she continued. “So if you think of DNA as a life’s writing system, then our system has just four letters to get all of the required information down.”
“A typical human DNA molecule is almost five centimeters long,” Ben said. “That’s not very microscopic.” He used his fingers to show the distance. “This long...all twisted and folded to fit inside each and every microscopic cell in our body.”
“Right,” said Trish. “But why use only four letters, you might ask? Why not more or less?”
“I don’t know,” Vars said. Her dad had tried to teach her this stuff, but she was an uncooperative student at best.
“All life in the solar system uses a four-base system to encode information,” Trish continued. “Thymine, cytosine, adenine, and guanine are the letters of our DNA code. Like other languages, there are rules—some letters go together, some don’t. So these four molecules—thymine, cytosine, adenine, and guanine—combine to form two groups of bases. The pyrimidines are composed of thymine and cytosine, with a single six-member sugar ring. And the purines are composed of adenine and guanine, with a double ring of sugar—one with five atoms and one made from six—attached on the side.” Trish used her fingers to demonstrate the molecular chains forming the rings of the organic molecules. She wiggled her thumbs and pinkies to indicate the attachment points.
“Trish, I’m grateful, really,” Vars said, “but organic chemistry has never been my strong suit, and now is not the—”
“It’s easy, really,” Ben said. “Just four nitrogenous nucleotide bases that form the letters of the DNA code. Well, five really, if you consider methylation—”
“Ben…” Vars pleaded.
“I’m just saying it’s not as complicated as it sounds.” He made finger rings and wiggled his own fingers. Alice probably would have done the same, Vars realized. She decided to just let the two of them talk. Grief is an idiosyncratic thing; everyone does it differently.
“Nucleotides in the DNA are pretty simple,” Ben went on. “There’s the phosphate group that sort of looks like a four-spiked star, a five-carbon sugar ring, and a nitrogen-containing base. It’s the nitrogen bases that come in four varieties—”
“Five,” Trish corrected him. “And we are up to ten artificial possibilities.”
“Yes, but only four are found in nature,” Ben said.
“So only four letters of the genetic alphabet across the entire solar system,” Vars said. She understood that much. The four-base code was something she knew a bit about…in very broad strokes.
“That’s right,” said Ben. “So again, why four letters and not two?”
“Are you asking me?” Vars said. Though she was utterly confused, she appreciated the conversation. Somehow, talking about the chemistry of life with these two goofy scientists was making her feel better. And Ben was beginning to look less sour. Trish too. It was good to talk about stuff that took up one’s whole concentration. There was no room for anything else.
Ben smiled. “Okay, I’ll explain. DNA is a double helix, as I’m sure you know.” Vars nodded. “But amino acids that our bodies need are produced by the genetic code of the messenger ribonucleic acid, mRNA.”
“And that’s about as far as I got in organic chemistry. Sorry.” Vars smiled shyly.
“—so this makes for three nucleotide bases per codon.” Trish pushed on regardless of Vars’s protests. “Making a total of sixty-four possible combinations,” s
he said as if the conclusion was self-evident. It wasn’t, not to Vars.
“Uh…” Vars felt lost and her focus slipped. Apparently there was still room in her mind for distraction after all.
Trish rolled her eyes at her. “Four to the third power?”
“Yes, yes, of course. Four times four time four. Sixty-four.” Vars felt like kicking herself for missing…whatever it was she had just missed.
“But if there were only two base pairs—two letters in the life’s alphabet,” Ben jumped in, “then it would be just two to the third—two times two times two—or eight possible combinations. So it would require longer strands of DNA to get the same information across. It’s like a coded message—the more symbols you’ve got, the easier it is to communicate. Got that?”
“I think so. Four letters, sixty-four combinations,” Vars said. “Two letters, only eight. Got that. But wouldn’t more be better? Didn’t you just say there were ten possible base pairs?”
“Theoretically,” said Trish. “Or synthetically, I should say. Alice managed to create artificial base pairs in her lab back in the Vault. It was one of the reasons Ian hired her.” Vars didn’t know that.
“That woman is brilliant,” Ben said. “Or—was…”
Trish gave him a dirty look—don’t go there.
“Yes. Sorry. So, to get back to coding genetic information,” Ben said. “Two was not enough—it takes huge strings of DNA to code the necessary proteins of life. Just think of an alphabet with only two letters—any little bit of information written with only two letters would take a ton of room to express. Books would be enormous; scientific papers insufferably long…” Trish kicked him to stop. He smiled sheepishly and continued. “This means it would be easy to mess things up—mutations or transcription errors would be more common. Six letters is better for the density of information transfer, but difficult to set up. Too complex for life. So four—”
“Is the Goldilocks number,” Vars said. A familiar principle, one she’d seen over and over again.
“It’s all about replication, information transmission, and error rate,” Ben said. “The more bases, the longer it takes to replicate, the more information is passed, the higher the error rate. A four-base system, using thymine, cytosine, adenine, and guanine, is almost forty percent faster than an only thymine-adenine base system and one hundred thirty-three percent faster than an only guanine-cytosine base system. Which means that evolution would have taken a billion years longer for a thymine-adenine base system and over two billion years longer for a guanine-cytosine one, assuming a four-billion-year history of life on Earth. That’s a huge difference.”
“Huge,” Trish repeated.
“Evolution requires the information to be passed on from one generation to the next,” Vars said to show that she was following. “It matters not only how many letters but which letters are used to pass this information on.”
“Precisely,” Trish said. “And a cool thing that Alice explained in one of our early meetings was the reason behind homochirality—our life’s preference for a left-handed versus right-handed configuration of amino acids.”
“Wait. Did I miss something?” Vars asked. “I thought we were talking about the DNA code letters.”
“Trish likes to jump around,” Ben explained. “Especially when she has an interesting tidbit of science that her audience doesn’t know but might find fascinating.”
“More mind-blowing than fascinating,” said Trish. “But you tell it, Ben. You explain it better.”
He sat up a bit straighter. “Before Alice, our group always discussed the handedness of the molecules as the result of the founder effect.”
Vars knew that principle. It essentially stated that the first population possessed various traits for unknown reasons—perhaps for arbitrary or temporary reasons—and that those traits became the de facto standard in subsequent generations, for no reason other than that’s how things started out. Like the tendency of most mammals to have five digits on each limb—something in deep prehistory had five bones, those bones gave rise over millennia to five fingers. “The founder effect is all about the initial conditions,” she said to demonstrate that she knew what it meant.
“That’s it. But there is a reason for the homochirality observed in life,” Ben said. “It’s because our galaxy rotates in one direction,” he said dramatically, “thus creating a chiral spin and a certain magnetic orientation. So the Milky Way’s dust particles polarize starlight in one particular direction. This polarization causes preferential degradation of right-handed molecules over left-handed ones. There are still right-handed molecules around—in fact, some bacteria are known to use right-handed amino acids—but it’s not the norm. Humans rely only on left-handed amino acids—”
“And the nanobots preferentially bond to those,” Vars said, sitting up straighter. “They’re left-handed too.”
“Yes. And because life in other star systems would have had to deal with the same galactic conditions…”
“The same chirality for the entire galaxy.”
“And one more thing,” Trish said. “Even though gravity, electromagnetism, and strong nuclear forces don’t have a handedness—they are achiral—the radioactive decay of the weak nuclear force is chiral. Beta decay creates electrons that favor a particular spin, which in turn are preferentially more damaging to the right-handed amino acids. Again, the left-handed amino acids win.”
“Well, you’re right about one thing,” Vars said. “My mind is blown.” And she truly felt a better. A little bit of Alice stayed with them. The Mims didn’t take away all of Alice’s insights. There was comfort in that.
Vars woke up to a low but insistent hum. It resonated throughout the ship but wasn’t one of alarms that they were all drilled on, signaling life-or-death situations. It sounded like a bad microphone switch somewhere out in ship corridors. Vars sat up and found Ben on the floor curled up with Trish. Both had fallen asleep right there after their late-night discussion. Carefully, so as not to disturb them—let them rest until she knew more—Vars slipped out of her room to investigate the sound.
There was something about being inside a spaceship, even grounded, that reminded Vars of her stomach—she heard random noises, none that she definitively recognized the source for, but they all seemed relatively benign if rather off-putting on occasion. Either way, humans were very good at ignoring even the strangest things once they became common. So in no time at all, Vars stopped hearing the bangs, clacks, pings, and groans onboard their ship. They became background noise. This persistent hum was different. She didn’t recognize it. It was new.
The corridor outside her cabin was dark; lights turned to sleep mode. But Vars knew there was always someone on duty, even if just to monitor for any possible messages from Earth or Luna. The scientists were allowed a looser schedule, but Liut kept his people on a steady duty rotation.
She walked-slid to the bridge, keeping one hand on the rails at all times. Mimas’s low gravity required everyone to use handholds to avoid bumping into walls and ceilings. She was covered in bruises, learning the hard way that proprioception required a lot of experience before it became automatic. All of Vars’s experience with how to move her body through space had to be relearned, first for the journey here under the simulated gravity and then for the tiny moon’s gravity.
She encountered no one in the corridor. Perhaps everyone is asleep? she thought stupidly. Her heart rate ratcheted up, and the sweat on her hands made the handholds slippery.
The door to the bridge was wide open. The lights inside were set at full brightness, as always. Vars propelled herself forward.
There was no one there.
Chapter Seventeen
Northern Finland and Norway were more populated than one would expect, given their inhospitable climate. This was especially true along the coasts, and more so after the Triplets Event. Still, a good port
ion of the population was seasonal. Away from the moderating effects of the coast, some winter days were colder than the surface of Mars, after accounting for wind-chill. Minus forty degrees wasn’t a rarity, but an expectation.
Then again, it was easier to get around when the land was frozen solid. All those bays and fjords and thousands and thousands of lakes and ponds—even simple puddles, swamps, and bogs—they could all be traversed directly when frozen over, saving days of roundabout travel. This meant that if Matteo could get their snowmobile to work—if it wasn’t too cold for the battery and the fuel didn’t turn to jelly—he and Phoebe would be able to get to the wardens’ station in a day. But if they had to walk or ski… Hypothermia was a real threat this far north. It all depended on the weather, and they had no way of getting forecasts at the moment. They just had to take their chances and hope that there wasn’t a big storm brewing out there on the day they chose to leave the lab.
From the wardens’ station, it was just a few more miles to the seed vault. Unfortunately, there were no roads between the two locations. The wardens were careful to take a different route every time they made a delivery, to ensure that no permanent trail developed. This was both for the Seeds’ safety and to keep them isolated…sometimes against their will. But Matteo had made that journey on foot once before, with a small child in tow besides. If they could get to the station, he was sure he could get them to the Vault. But he hadn’t made up his mind yet as to whether they’d go that far. One thing at a time, as Elder Alaba would say.
He crawled under one of the lab desks, using the blankets for cover—he didn’t want some stray camera to catch on to what he was doing—and wired another explosive into the net of charges he and Phoebe had been setting up over the last several days. The explosion might not be hot enough to destroy all the bots in the lab, but it would be big enough to collapse the structure and expose everything inside to the outside temperatures. And perhaps the combination of heat and cold would be enough to at least neutralize the Sophie-bot long enough for them to escape.