Oceanworlds

by J. P. Landau

  In our Solar System, Titan is the only world beyond Earth with stable surface liquid bodies—excluding the scorching lava lakes of Jupiter’s moon Io. The weather below Yi sloshed in all three states: solid, liquid, and gaseous. Not water, but methane and ethane and other hydrocarbons. Water did abound but in the form of rock-hard pebbles and boulders scattered around its surface. That’s shamefully inaccurate! There is liquid water. Not on Titan but in it. The moon was a world of two ocean decks: the exterior hydrocarbon seas and an interior water global ocean as salty as the Dead Sea. But bigger. Much, much bigger: in quantities many times larger than all of Earth’s oceans combined, hidden dozens of miles under Titan’s surface. The Cassini probe, that shrewd sleuth, confirmed its existence in 2012 by inference: the way Titan flexed under Saturn’s gravity was only possible by a shell decoupled from the moon’s core.

  Kraken Mare, Titan’s largest exterior sea, glittered beneath.

  Hours before, Shackleton had released a heat shield designed to brake against Titan’s atmosphere and parachute its payload to the moon’s surface. This was the Grasshopper, an autonomous explorer that—all going well—would touch down near Kraken Mare the next day.

  The Grasshopper was a direct descendant of the iPhone. Components miniaturization and rechargeable battery improvements allowed a revolution in unmanned aerial vehicles. This three-foot-long quadcopter drone, however, was an exercise in superlatives. It carried both a laboratory and a meteorological station on board to study Titan’s atmosphere and to search for organic molecules and chemical signs of life. It would communicate directly with Earth through a dish antenna the size of a platter. At each landing site it would recharge its batteries from a shoebox-size nuclear thermoelectric generator. It would fly once a day. If this seems hurried, bear in mind that a Titan day is sixteen Earth days long. And in a few days, it would have covered the distance the long-lasting Opportunity rover covered in its fifteen years roaming around Mars. I suppose it sounds less impressive when you consider it was a little under thirty miles. Its cameras would image the terrain and scout for the next scientifically interesting site. And after Mission Control picked the exact route, it would fly and land autonomously.

  Grasshopper would achieve all this by fully utilizing Titan’s thick atmosphere—four times denser than Earth’s—and lower gravity—one-seventh that of Earth’s—which make it the easiest location to fly in the Solar System. In fact, thirty-eight times easier than back on our planet, to be precise—here, the Wright Brothers wouldn’t have stood a chance against their countless predecessors strapping wings to their arms.

  Minutes later Yi screamed, “The Magic Islands are back!” The Cassini team had so dubbed the mysterious features that appeared and vanished on observations taken years apart. The phenomenon could be vast patches of bubbles or subsurface ice rising to the sea surface or even waves. At that time the hunting was with sling and stones. Now we brought the bazooka. He zoomed in and suddenly got the chills. “They—they’re giant waves! I—I’m watching the sunlight reflect off them—” His voice broke down. This is one of the happiest moments of my life. They moved in front of his eyes, glinting in gold, 590 miles below. Through the virtual reality goggles, science had healed his blindness and fixed his sight to within a few miles of the fantasy world below. Yet it wasn’t that. It was the exhilaration of discovery. It was internalizing that those waves below and indeed himself were partly made of hydrogen, all of which was created by the Big Bang at the beginning of time. It was about no longer sensing the cosmos around him but becoming a part of it. He felt the dopamine rushing in his body. But that’s the drug fix, and this is much deeper than bodily sensations. The sense of time dissolved, he abandoned the future and the past, delighting instead in the simplicity of the now. I could die this moment and it would be fine.

  And then it was over. Yi saw the mammoth Titan recede. Distant, indifferent, almost aloof.

  But the memories would stay with him for good.

  * * *

  23 Fully immersed through the goggles, Yi saw Cassini’s topographic map in all directions, and right below him the new data being processed in real time, replacing a 200-mile-wide strip with newly 3D textured mapping. The resolution was astonishing. Each pixel within the strip represented ninety square feet on the ground, almost one hundred times better than Cassini’s radar, which repeatedly scanned Titan’s surface from 2004 to 2017 during its 127 flybys.

  47 | The Search for Life

  Hours later

  ENCELADUS

  Never mind the food, this was Derya’s most invigorating breakfast ever. He looked through the window one more time at the collecting box sitting outside Caird. The snow already reached half its height. More than an adequate sample to begin testing!

  “Today we answer whether Enceladus is inhabited rather than merely habitable,” said Derya. The words rolled out of his mouth with the pace and rhythm of a carol.

  “I’ve already told you, temper down. This isn’t Germany playing in the World Cup Final. We’re not bystanders here. We’re referees. The instrumentation will do the work, but then human interpretation follows. We’re the only two pairs of eyes on the frontline. You owe it to the world to be less fizzy and more impartial.”

  “You’re starting to sound like C-3PO.” Derya got a blank stare from Sergei. “Star Wars? Sorry, forgot you skipped childhood.”

  “Even if alien life is teeming down under, there’s no certainty we’ll be able to find biosignatures in the geysers’ ejecta,” said Sergei.

  “Ejecta? Bloody hell! Call it snow at least. Find some poetry in life, mate—and given you got all technical, sure, there’s no certainty but there’s a framework supported by ninety years of empirical evidence in oceans, rivers, lakes, ponds. What’s incontrovertible is that Cassini discovered silicate crystals in the jets, which means two things—well, make it three. First, there’s hydrothermal activity coming from seafloor vents. Second, the observation of silicon-bearing compounds is in itself a demonstration that seafloor material is rising the tens of miles of ocean depth and traversing through the ice shell to then be expelled in the plume at high enough concentrations to be detected. Third, back home hydrothermal vents are thriving concentrated ecosystems … now the speculation: bubbles are the ones ferrying the detected particles up, and on Earth they tend to collect organic matter and microbes along the way as they climb the water column, which can increase biological concentrations up to a thousand-fold compared to those in the bulk ocean. So yes, I’m convinced that whatever shows up here will be representative of what’s down there.”

  “Moderate the bullishness. Don’t underestimate the capacity of evolution to innovate. Bubbles rise because they’re lighter than water. Predators could have evolved to have nets passively waiting for bubbles to pass through to scrub them of microbes.”

  “Sounds far-fetched,” said Derya.

  Later, the hatch slid open and Derya went over to the collector box and sealed it before re-entering the microbes’ infested capsule. Humans are giant worlds inhabited by microorganisms in mostly symbiotic relationships. Touching or simply breathing instantly colonizes any sterilized environment.

  Afterward, the spacesuits were out and they waited for the thawing. The laundry list for that day was long and yet both were focused on the transparent box cover. Derya’s head raged with the realization that history may be about to change with whatever was inside that container no bigger than a shoebox, sitting a foot away from his face. I get whiffs of hospital smell—which is good. Aseptic and all.

  Sergei brought the digital holographic microscope and Derya positioned it over the collector box. Specifically designed to detect the hardest of samples—a semi-transparent, micron-sized, single-celled, featureless, motionless organism—information was fed into a computer algorithm that reconstructed the image as a 4D hologram, 3D plus time. It thus sidestepped one of the primary criticisms of the use of microscopy for life detection: the difficulty of discriminating cells from mi
neral grains or organic material.

  Derya turned it on. At 97x magnification the screen showed a cluster of perfectly symmetrical hexagonal ice crystals. The tree-like dendrites at the end were beginning to show deformation due to melting. Zoomed to 347x it showed never-ending complexity as new wild structures were revealed. Zooming to 1,920x showed thawing was now evident, but there was still geometrical perfection, a long, flat surface engraved with pyramids, cones, cylinders. He turned it off.

  “When hunting, you only view through the crosshairs when ready to shoot, otherwise you lose perspective,” he said.

  They waited until the melting dissolved the ice crystals. Alien liquid water. Bubbles formed at the top and around the sides, like beer foam.

  “Looks like tap water,” said Derya with an enthusiasm that could only mean it wasn’t.

  “Holy water does too, yet it protects against evil spirits and cures cancer. Do not judge a book by its cover.”

  “Are we ready?” asked Derya. Sergei nodded. “And what if we find nothing?”

  “Then it’s either a sample problem or the absence of life, isn’t it?” said Sergei.

  Scanning for signs of life began. The first test was for an alien organism in motion, an unambiguous, 100 percent confident detection of life. A quick pass started at 100x zoom for sixty seconds. Nothing. 200x. Nothing. 400x. Nothing. 800x. Nothing. Derya glanced at Sergei, who remained absorbed at the screen. 1,600x. Nothing. 3,200x. Computer detected thirteen corpuscles to which it superposed blue circles for motion tracking on Caird’s screen. Derya’s reaction was more relief than excitement.

  And then nothing happened for five motionless minutes. It could well have been a photograph, both the water sample and Caird’s cabin.

  “Calm down,” said Sergei to an increasingly restless Derya. “The water temperature is 35.6 degrees Fahrenheit. The training samples barely moved during the first hour.”

  A year before launch, a team including Sophia, Yi, and Sergei flew to northern Canada, well within the Arctic Circle, to an uninhabited piece of land called Axel Heiberg Island. Some 50 million years before it had been covered in wetland forests, now mummified under hundreds of feet of permafrost. Over a week, they calibrated the digital holographic microscope and trained on bacterial samples obtained from englacial ice and an under-ice lagoon, simulating Enceladian conditions. They learned to resolve subcellular features, spot microorganisms by recognizing shapes and swimming patterns, and deal with ambiguous cell-like objects.

  After almost an hour had passed, movement was detected by the software, not appreciable to either for a while. It was no impediment for Derya to hum “We Are the Champions.” He was temporarily immune to Sergei’s glare, instead doubling down by turning it into a chant while stirring his arms theatrically.

  As time and temperature went up, the movement accelerated and became progressively erratic.

  And Derya lost all composure.

  The computer had been tracking the path of every particle by drawing a line behind it. Within minutes most lines had gone from blue to red. All seemed to follow a random walk: forward, left, retracing, right, the scribble of a toddler—all but three.

  Sergei tried to remain calm, but the effort was increasingly futile. The engrossment was such that he no longer heard or saw Derya turn into a chimp. He was focused on one particle, bigger than the rest and with a non-circular form, moving in an almost straight line to the right. He saw himself falling into the anthropomorphizing trap. But I’ll be damned if that thing is not heading with an attitude toward the other particle, he thought.

  He could feel his increased breathing and heartbeat, and then the goosebumps arrived as he was taken into a stupefying crescendo.

  “I think—” but he didn’t utter the next words.

  And then in an instant Sergei’s particle blue path turned red. Seconds later they had all been disqualified. ‘Brownian Motion’ flickered on the top right corner of the screen. Using Einstein’s equations,24 the software had ruled the corpuscles’ movement was perfectly consistent with inanimate matter.

  They looked at each other, floored.

  “What now?” asked Derya, his voice suddenly vulnerable.

  “We move on to the next experiment: chemical detection. And we retry tomorrow after overnight incubation. Remember Axel Heiberg Island. We had a similar situation and the following morning the broth showed an increase in cell mobility, which made separating them from the background a much easier task.”

  “In God We Trust.”

  “Leave him out of it. You’re behaving like a televangelist. I don’t think God gave you reason just so that you would abandon it when we need it most. Trust in the experiments and the science behind them, physicist.”

  Short of a microscope, the fallback tool in the detection of life’s arsenal are long, organic molecules. Organic molecules are chains of atoms that have carbon as their backbone. As far as life on Earth is concerned, this is an essential requirement. But not a guarantee. Methane, CH4, is a simple five-atom molecule spontaneously occurring across the Universe, which has been detected by telescopes all over our as well as distant solar systems. The name of the game requires ‘long’ attached to ‘organic molecule.’25

  As the size of an organic molecule escalates, the probability of atoms spontaneously self-arranging decreases exponentially. In the case of a single protein, a mere pawn in those marvel city-states known as cells, the probability falls to zero. A protein is made by hundreds of amino acids—each amino acid itself composed by tens of atoms—forming bewildering geometrical shapes. That sophistication betrays the intervening hand of biosynthesis. But for smaller molecules, say a DNA fragment less than one hundred nucleotides long, the analysis is inconclusive.

  In lieu of size there are still two solid tools.

  One is chirality. Our hands look identical but are in fact mirrors of each other. The difference becomes obvious by superimposing one over the other. The molecule that gives spearmint its distinctive smell is an exact mirror of the one that gives caraway seeds their pungent aroma. Nature is ambidextrous, life is not. Non-living chemistry creates left- and right-handed molecules in equal amounts. But all of us are left-handed—nineteen out of the twenty amino acids forming every protein in our body are left-handed. Detection of prevalently left- or right-handed molecules all but seals the case for the existence of alien life.

  The other is the ratio between carbon-12 and carbon-13. All chemical elements have variants that differ in the number of neutrons, which are called isotopes. Carbon has fifteen known isotopes, but only two are stable. Carbon-12, with six neutrons and six protons in the nucleus, is ninety-nine times more naturally abundant than carbon-13. Finding an anomalous deviation from this 99/1 ratio would be a powerful signature of extraterrestrial life.

  The first day of sample testing concluded by running the two other instruments aboard Caird. The Enceladus Organic Analyzer, able to detect a wide range of organic molecules using lab-on-a-chip technology that had miniaturized into a palm-sized device that two decades prior would have taken a full laboratory—people included; and the Isotopic Mass Spectrometer.

  Derya had been making an active effort to work through the results without processing them in his head. After so many years waiting, the prospect of staring at them was intimidating. He was drained, the mental effort had permeated his body and he felt limp and lethargic.

  There was a cloud of unease hanging over Caird. They barely spoke during dinner.

  A double beep put them on the alert. The sample analysis had concluded and the summary of the chemical inventory sat on the screen, waiting for their attention.

  Derya was surprised to note Sergei wasn’t raising his head either. If he was by himself, he would have gone to bed without checking. But having another person in front turned it into a prisoner’s dilemma and the outcome unraveled within seconds. Both stared at the screen in silence, long enough to hear each other’s breathing.

  Derya finally said it. �
��It’s habitable … it’s lifeless.”

  Quantitatively, it was undeniably promising. All biochemical elements were present. Check. A significant portion of the building blocks of life: two of the four DNA letters, adenine and thymine; three-fourths of RNA’s letters; twelve out of the twenty amino acids required for protein assembly; various fatty acids; an assortment of other complex organic molecules, although none larger than fifty or so atoms. Molecular biologists would rejoice in the finding of long-speculated molecules potentially conducive to a parallel chemistry of life: compounds using silicon instead of carbon; and a modified adenine joined with thymine by an additional hydrogen atom, making a stronger bond. Inconclusive evidence, yes. But clearly positive.

  It was the last three lines that brought down the celebration. The cosmos’ remorseless indifference was once again manifest.

  Chirality: No Statistical Preference. All twelve left-hand amino acids had their right-hand siblings in the sample.

  Carbon Isotope Ratio: No Statistical Difference. Not only that, it was equal to nature’s abundance all the way to the first decimal place.

  And the final note of pessimism: Total Concentration of Organic Molecules in water was four full orders of magnitude lower than in Earth’s oceans.

  “The whole machinery of life is operational, but nothing here is actually alive … all the jigsaw pieces fit snugly, but nobody ever took the time to assemble them,” said Derya in a voice as bleak as his words.

  Sergei answered after an excessively long time, “Your logic is the same as dropping into Central Park on a winter night during a blizzard, and, not seeing anyone or anything, claiming sovereignty over America as the first human being to ever set foot there … you can’t extrapolate from a single sample.” But any persuasiveness was defeated by his delivery.