Oceanworlds

  Cassini saw a mammoth storm called the Great White Spot that develops roughly every Saturnian year, equivalent to thirty Earth years. The storm dredged fabulous amounts of water ice from the planet’s depths, depositing it atop the clouds. For a moment, it was larger than Jupiter’s Great Red Spot, with the biggest whirlpool ever witnessed, churning around the planet for twelve weeks until it encountered its own tail and sputtered out.

  Over the course of a month Cassini saw two giant storms on a collision course, each the size of the Earth, clashing and merging into an even larger one. Saturn is blanketed with electrical thunderstorms, some the size of the United States, with lightning bolts a thousand times stronger than those on Earth, suddenly emerging and lasting for weeks or even months at a time.

  It is known that storms on the gas giants can last months, years, or even centuries. Both of Saturn’s poles share enormous stationary hurricanes that appear to be raging uninterruptedly. The south pole’s is half the size of Earth. At the north pole, a colossal swirling eye wall the width of India surrounds its angry center. Cassini also studied one of the strangest climate phenomena ever witnessed, the north pole’s stunningly symmetrical hexagon-shaped jet stream, twice as big as our planet, with a shimmering aurora on top. The seemingly artificial shape provoked wild speculation until scientists reproduced it in the lab. In the gas giant, the paranormal quickly becomes commonplace.

  The rings of Saturn are the magnificent remnants of a comet or asteroid that ventured too close and was savagely torn apart by the colossus’ gravity. Like fractals showing never-ending complexity at every scale, what seem like two giant disks from afar on closer inspection become seven major subdivisions, which themselves become a kaleidoscopic psychedelia of endless minor rings. They are formed by trillions of chunks of water ice, ranging in size from tiny, dust-sized icy grains to blocks as big as mountains. Theirs is a high-wire act, a harmony of exquisite balance between their sheer, delicate magnitude and Saturn’s unsparing gravity.

  And then September 15 2017 came and Cassini plunged into the gas giant in a death dive, a shooting star across Saturn’s sky. The end of the intrepid probe’s quest marks an inflection point in the exploration of the Solar System: the completion of half a century of cataloging every self-respecting stone or snowball around the Sun. The mapping age of human space exploration is over. Now starts the biological search to attempt answering what may be the most fundamental question ever posed: Are We Alone in the Universe?

  The Search for Extraterrestrial Life

  Our once-held belief that the Solar System is a dry, barren desert with a single shining beacon of hope called Earth was replaced, following Cassini, by one soaked with water. Scientists looking for extraterrestrial life have long stuck to a golden rule: ‘follow the water.’ And before Enceladus, the Goldilocks zone—where it wasn’t too hot for oceans to boil nor too cold for them to freeze—barely covered the orbits of Earth and Mars. The small moon proved that sunlight is not the only way to heat a celestial body. In very particular conditions, gravity can do it as well. Had Enceladus’ orbit around Saturn been perfectly circular, it would have been a spherical ice cube through and through. But the constantly changing distance from the massive body shrinks and expands the moon’s waist, creating friction and heat in its interior. Using what Enceladus has taught us, we now know that at least two other Saturn satellites, Titan and Enceladus’ big sister Dione, harbor oceans of water under their cold, icy surface. So do Jupiter’s big moons Europa and Ganymede. Even Pluto, four times farther from the Sun than Saturn, may hide liquid water underneath.

  Compare this with the continuous disappointment of Mars. We fell in love with the Red Planet in part by it being our immediate neighbor, but mostly because it promised so much. In the early days, the optimism of finding life was intoxicating on a planet covered with telltale signs of a wet past. Things deflated with Mariner 4’s 1964 Mars flyby, which not only failed to spot Martians, but also showed a cratered, bone-dry, and dead world. Today, after six decades, tens of billions of dollars, thousands of people dedicating decades of their lives, and almost fifty missions to Mars, no permanent liquid water has ever been observed, nor one single molecule from past or present life. A reverberating technological triumph on the one hand and a resounding biological setback on the other.

  Antennaed green men nowhere in sight? Back to basics. A minimalistic approach to life. It began in 1977 when a group of marine researchers discovered the much-theorized hydrothermal vents deep down under the sea back on Earth. Superheated gushers nourishing a rich ecosystem of life. Had we finally found the primordial soup? The place in the ancient oceans where life originated?

  Some context is in order.

  For centuries we thought Hell existed in Earth’s center. That turned out to be quite right. Our globe’s radius is almost 6,500 kilometers. The first half is the core, consisting of a solid heavy metal sphere surrounded by molten iron. It’s about 6,000 degrees Celsius, the Sun’s surface temperature. The motion of molten liquid iron creates Earth’s powerful magnetic field that, far beyond giving us the compass, shields the atmosphere and protects living things from both solar wind and cosmic rays’ harmful radiation. Our neighbor, Mars, once had an agreeable temperature and an ocean covering a quarter of its surface, but something turned off its magnetic field. Today’s Mars’ desolate freezing wasteland is the consequence of losing 90 percent of its atmosphere to the solar wind.

  The second half of Earth’s radius is composed of the mantle, a hot rock layer behaving like a viscous fluid. Scientists recently discovered deep-in-the-mantle water reservoirs many times larger than all surface oceans combined. Thanks for that. If they were up above, only a few mountaintops would pierce the waterline.

  But our interest is on Earth’s skin—the crust, barely five to fifty kilometers thick—standing above all else. It is hard yet brittle like eggshell, cracked into several segments called tectonic plates. The plates float over the mantle that moves them agonizingly slowly. Over eons, this shuffling broke up Pangaea, the supercontinent that existed 175 million years ago. The movement is infinitesimal yet permanent: the Atlantic Ocean grows at roughly the same pace as your nails, and that makes it twelve meters wider than when Columbus crossed it; Everest keeps getting taller by around one centimeter per year.

  The boundaries between tectonic plates do two things. Collide and slide past one another, forming mountain ranges like the Himalayas, as well as volcanoes, earthquakes, and tsunamis like the Ring of Fire around the Pacific Ocean. Or they move apart, creating faults, cracks, and new islands as these two-way conveyor belts allow lava seepage from deep down in the mantle that later solidifies and renews the Earth’s skin.

  Enter hydrothermal vents. Back in 1977, those marine geologists found the smoking gun on the East Pacific Rise, an underwater, mid-oceanic ridge where the plates, especially near Easter Island, are diverging at the fastest rate in the world. Here, where the guts of the Earth are exposed, superheated water comes in contact with near-freezing seawater—black or white smokers depending on the feeding minerals from below. The minerals precipitate forming tall stacks of chimneys with cathedral-like structures, essentially small underwater volcanoes such as Lost City, a hydrothermal field in the Atlantis Massif a kilometer below the Atlantic Ocean.

  The spotted sites quickly multiplied and all proved to be oases for life, ultra-rich ecosystems in perpetual night with fantastically strange deep-water creatures: giant tube worms, nightmarish luminescent pelican eels, meter-long spider crabs, jumbo snails. But the magnifying glass is over the base of that food chain, bacteria and archaea—unicellular microorganisms that in total absence of sunlight mimic the activities of their cousins far above, deriving their energy from chemical reactions instead of photosynthesis.

  In April 2017, researchers shattered the record for the earliest forms of life by reporting fossilized bacteria from an ancient hydrothermal vent in Hudson Bay, Canada, that may have lived as early as 4.28 billion years ago.
That’s barely 100 million years after oceans formed on Earth. This crowns the accumulating body of evidence that points to the proverbial primordial soup at the root of our tree of life having developed around a hydrothermal vent. As unlikely as coincidences go, on that same month NASA’s Jet Propulsion Laboratory announced Cassini’s discovery of hydrothermal activity in Enceladus’ subsurface ocean.

  The excitement about Enceladus is not just understandable, it is inescapable. Life as we know it requires four primary ingredients: liquid water; a source of energy for metabolism; the right chemical ingredients; and time for the concoction to ferment. Enceladus has them all, in spades. We stumbled upon the Holy Grail in our search for alien life: the key to potentially answering whether we are the only ones.

  If Enceladus broke all the conventions about where life as we know it can develop, Titan is the prime candidate for life as we don’t know it.

  It’s a fact. Life on Earth requires liquid water. At the microscopic level, 75–85 percent of the cell volume in every living organism is liquid water; 60 percent of a human adult’s body weight is liquid water. Therefore, liquid water is a prerequisite for life elsewhere in the cosmos.

  Not so fast. We fall into the trap of thinking from an Earth-centric point of view. From general principles the assertion is broader: life anywhere probably requires a liquid solvent. The definition of life is deceivingly simple yet it took decades to hone in on ‘something that can both reproduce and evolve.’

  And in order for life to reproduce and evolve we must have a medium where atoms interact frequently and promiscuously to form chains of atoms, and those molecules must in turn interact frequently and promiscuously to form increasingly complex structures.

  A solid doesn’t cut it. It packs atoms and molecules tightly together—good. But it locks them in place, allowing only rare collisions and interactions—bad. A gas doesn’t cut it either. Atoms and molecules are freer than in liquids but because the gas density is less than a thousandth of liquids’, there’s a much lower chance for collisions and interactions. The Universe is ancient at 13.8 billion years old. Yet life on Earth took at best 100 million years to occur. So, it is also simply too young for life to have occurred in the snail-paced chemistry action world of gas, or worse, sloth-lingering world of solids.

  A liquid allows high concentrations of atoms and molecules and doesn’t put tight restrictions on their motions. Therefore, it allows complex chemical processes, as molecules interact and form new types of compounds. Liquid water (H2O) has the advantage of being formed by hydrogen and oxygen, the first and third most abundant chemical elements in the Universe. Disadvantage? It’s only liquid between zero- and 100-degrees Celsius. Methane (CH4) is formed by the first and fourth most abundant chemical elements in the Universe, so no slouch either. The methane oceans of Titan are at -180 degrees Celsius. Perhaps the reason Earth doesn’t have methane-based life is because our planet has never been that cold. Methane boils at temperatures above -160 degrees Celsius, no wonder it is known to us as natural gas.

  A golden age in the search for extraterrestrial life is about to commence. As Einstein once said, “Scientists investigate that which already is; engineers create that which has never been.” Soon, the engineering marvels about to be unveiled by SpaceX and Blue Origin will help trigger the first large-scale, systematic search for alien life around the cosmos: in our backyard, by flinging manned and unmanned spacecraft armed to the teeth with detection tools to every corner of our Solar System; or in the vast expanse before us, by the launch of previously unthinkable space telescopes that will be able to search for atmospheric markers betraying life in planets tens or even hundreds of light-years away.

  Warning, exhilarating times ahead.

  Dramatic License

  Here’s a non-exhaustive list of areas where the story deviates from reality. As you read them, perhaps it will become apparent why I decided to keep them in the novel:

  1.Chapter 36. Here is Linda Spilker and Leigh Fletcher on impact scars on Saturn, “There are many variables that go into the visibility of the impact scars on giant planets, but chief amongst them are the momentum (i.e. mass, velocity) and the angle of impact. If the momentum were identical to Comet Shoemaker-Levy 9, then the angle is what matters, because the bolides super-heat their entry columns, causing the forced ejection of material back out of the atmosphere, which then crashes back down in concentric rings around the entry point. The debris itself is actually chemically altered Jovian or Saturnian air. A straight-on collision would create a near-circular bruise but it’d be deeper, whereas an oblique collision would be shallower and create a more elongated scar. It’s true that Saturn’s hazes are thicker than Jupiter’s, but our models for Jupiter had the impact debris very high up, above the surrounding hazes, so my first instinct is that things would look similar on both planets. One other thought—if the impactor were a dry, volatile-depleted asteroid, then it might be able to reach below Jupiter’s water clouds (and hence the debris would include a lot of oxidized species), but not Saturn’s because they’re deeper (and hence the debris would include a lot of reduced species). Bottom line: it would produce a visible scar. One idea around being able to see a visible scar on Saturn might be if the impact is in the winter hemisphere, covered by ring shadows. The shadows might ‘hide’ the impact but would also make it harder to see from Earth.”

  2.Chapters 45, 67–73. Here is Alexander Hayes’ perspective on various Titan issues,

  a.The Titan geography described in the novel is violent and jagged. However: “When I think of Titan’s landscape, I envision a rough water-ice terrain that has been blanketed by a billion or so years of organic material falling out of the sky. The water-ice mountaintops peak out of a rather smooth organic layer a few hundred meters thick. In fact, ~60% of the surface is covered by relatively featureless smooth plains; equatorial dune fields cover ~17%; the poles (60-90 N/S) cover 13%; the lakes/seas themselves cover ~1.4%; and everything else (mostly mountains/hummocks) covers the remaining ~10%.”

  b.Regarding waves on Titan: “While waves are ~7 times larger on Titan as compared to Earth for the same wind speed, wind speeds on Titan’s surface are very low (1 m/s is a big gust on Titan) … I don’t think Titan would produce large waves except in the rare cases of a freak storm.”

  c.Regarding high-altitude winds: “The drag force you feel due to wind at a given altitude is proportional to pressure. Since pressure is exponential with altitude, it means that the stronger winds at higher altitudes exert far less drag than winds of that magnitude would near the surface. To be completely honest, my intuition is that a spacecraft or probe on a non-powered descent (i.e. parachute) would have a pretty smooth and boring ride after they have shed the insertion velocity.” In other words, I have committed the Andy Weir sin.

  d.Regarding a storm moving from Titan’s equator to the poles: “There is still a lot we do not know about Titan’s climate and meteorology. A converging story, however, is that the equator and mid-latitudes are characterized by infrequent but heavy rain storms (Cassini witnessed one in 2011). The poles, on the other hand, are characterized by lighter, more frequent rainfall. In fact, some models have the poles continually ‘misting’ during certain seasons (not sure if these will hold up to scrutiny in the coming years). Regardless, the large storms that we see at the equator do not themselves make it up to the poles.”

  e.Regarding tides and directional flows of water in the Titan seas: “The static tides exerted by Saturn on Titan are much stronger than the static tides exerted by Earth on the moon (and vise-versa). This is what gives Titan its tri-axial ellipsoid shape. The dynamic tides, however, are actually less. Titan is a slow rotator and tidally locked. In addition, Cassini found that Titan tends to deform with the tides instead of act like a rigid solid body (it has a high Love number). This is one of the ways we confirmed the presence of the internal ocean. So, as a result, the tidal amplitude on the seas is more like a few tens of centimeters than it is a few tens of met
ers.”

  3.Chapter 78. In the year 2032, Jupiter will be at the opposite end of the Solar System as seen from Saturn, making a reverse slingshot non-viable—the 2019–2022 window would be the right time, when the planet is between Saturn and Earth.

  Acknowledgments

  As with any large, prolonged project, there are plenty of fingerprints all over this novel. I am, however, particularly indebted to:

  Marie, my one and only, for everything—especially the half a decade when the person by your side was many times a billion miles from home.

  My friends Nichole Pitzen and Arnau Porto, for their shrewd comments. Nichole, you are accountable for turning Hes into Shes.

  Eduardo Bendek and Marcello Gori, two prime engineers from JPL, for their technical review, enthusiasm, and commitment to making science mainstream again.

  Linda Spilker, none other than Cassini’s Project Scientist, for her outstanding contributions to humankind and—closer to home—her contributions to this book.

  Alexander Hayes, Professor of Astronomy at Cornell and leading expert on Titan, for his extensive notes and brilliant, invaluable insights.

  Quora and Wikipedia, for the free enlightenment.

  The Atacama Desert’s skies, under which I lived for two years as a child, which stabbed me in the eyes with haunting, indelible vistas of the cosmos.

  Lastly, all mistakes and omissions are exclusively mine. A few times, to benefit the plot or for dramatic purpose, I deliberately ignored certain comments or facts.

  About the Author

  J.P. Landau is a pseudonym.

  The man behind it likes to think he’s still in his early 30s, but that would only be possible if he had been Kerouac typing up On the Road. Instead, Oceanworlds took north of four years to complete. He does look and feel younger than he did in his mid-20s, when he worked in the cash-rich, soul-crushing world of investment finance. He cleansed for three years at Stanford, and afterward co-founded an energy storage company.