“This is Yuri Dushek,” said a deep voice with a slight accent.
“What can I do for you? And who gave you my private phone number?”
“I am sorry to bother you. I would like to make you an offer. I will not beat around the bush. I am looking for a capable commander for a private space expedition. And who would be more suitable than you?”
“I would like to spend some time with my family now.”
“I understand. The expedition will not start for two years. Of course we will hire your husband as well, and you can bring along your son. As the trip is privately financed, we can make any arrangements you need.”
Dushek had become rich in the oil business, but right before its collapse he had switched to modern technologies. He owned a whole empire of companies engaged in AI research. He used that to finance half of the Russian space program, it was said.
“You know, I like my role at NASA.”
“That is not what I heard. An office job does not suit you.”
Of course the man was right. For the moment the NASA job was very convenient, but she could not imagine being an administrator for the rest of her career.
“I really do not need any changes right now. Could we talk again in two years?”
“No, unfortunately. You are my first choice, and if you turn me down I need to hire someone else.”
“Then do it. Was that all?”
“Please do not hang up yet. Maybe the reason for this journey might change your mind.”
“I hardly think so, but I will give you one try.”
“The goal of this expedition is to rescue the body of Dimitri Marchenko from the bottom of the Enceladus Ocean and reunite it with his consciousness.”
Author's Note
Once more, it’s my pleasure to be able to greet you here! After the hot and icy experiences on the volcano moon, you may need some recovery time, and so does ILSE’s crew. I really hope you enjoyed reading the book as much as I did writing it.
After reading this book’s predecessor, The Titan Probe, a Canadian reader asked me, “What is your background? Some of your descriptions of, for example, the effects of life in a low-gravity environment are so vivid and realistic that it seems you have experienced them personally.”
I really wish I had. But in fact, I have only experienced such things in my dreams, so far. (I can—fun fact of the day—control my dreams to some extent, and I especially love to dream about flying with my own wings.) Maybe that helps me in recreating the experience with words. What also helps is having my fantastic editors, Marcia and Steve. I owe them a big ‘thank you’ for their great work.
But to answer the question from the reader: I’m just a physicist who learned to write. After I had earned my diploma, I discovered nobody needed physicists. So, I decided to make a profession out of my writing hobby. For 25 years, my job was explaining hard science to everyday people. Nowadays, I still edit SPACE, a magazine you can only find in stores (see emedia.de/magazine/space/). As part of this job, I actually landed on Mars last year… well, on a simulated Mars environment! In reality, it was in the Omani desert. That adventure is the closest I have come to being an actual astronaut. But I hope that soon, in my lifetime, tickets to space through SpaceX, Blue Origin, or Virgin Galactic will become cheap enough so I can book one. What about you? Would you travel with me? And what if the ticket was one-way?
Well, that’s enough recovery time for now. We have a mission waiting for us… another mission to Enceladus! Mysteriously, the former ILSE crew gets an offer they cannot resist—to rescue their doctor. They will return to Enceladus, and so can you, in my next book, Return to Enceladus, available for preorder here:
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If you register at hard-sf.com/subscribe I will keep you informed about new Sci-Fi novels being published. You will then receive a free PDF version of The Guided Tour of Io with color illustrations.
And if you somehow missed either of the first two books of the series, it’s not too late to find out more about these characters and their mission. You can purchase The Enceladus Mission and The Titan Probe on Amazon.
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I have to ask you one last thing, a big favor: If you liked this book, you would help me a lot if you could leave me a review so others can appreciate it as well. Just open this link:
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Thank you so much!
The Guided Tour of Io
Introduction
Io is a very special moon. It was named after a lover of the Greek god Zeus, who in Roman mythology is called Jupiter, and now she faithfully orbits him.
In Greek mythology, Io’s affair with Zeus brought her nothing but bad fortune. As the mortal daughter of the river god Inachos, who was also the first king of Argos, she might have led a pleasant life if only Zeus, the leader of the gods, had not fallen madly in love with her. Unfortunately, his wife Hera found out, and to protect Io, Zeus turned her into a silvery heifer. However, clever Hera was not deceived, and she demanded the heifer as a present, which Zeus could not deny her. Hera had her prisoner watched over by the hundred-eyed giant Argos—with the eyes of Argus or Argos, as the expression goes. Zeus, in turn, wanted to give Io a chance to flee, so he sent Hermes, the divine messenger, who first lulled Argos to sleep and then killed him. Hera sent a gadfly to follow the fleeing girl, a malicious insect, the larvae of which hatch and mature inside animals like cattle. The buzzing of the insect scared Io so much she fled all around the Mediterranean and finally reached the Nile, where Hera graciously returned her to human form.
This short form of the myth is nothing compared to the tortures the moon Io experienced over billions of years—or would have done, if moons could feel anything. Because of its proximity to the giant planet, the moon is kneaded by Jupiter’s gravitational pull, forcing Io to constantly change its shape.
What kinds of volcanic activity are there on Io? How is the interior of the moon structured? Does Io really provide opportunities for life to develop? Come with me on a factual journey to the fourth-largest moon of the solar system.
Orbit and Shape: Jupiter’s Lover
Seen from Jupiter, Io, with its diameter of 3,643 kilometers, is the planet’s fifth moon. Its distance from the center of Jupiter is 422,000 kilometers, but it orbits at 350,000 kilometers from Jupiter’s uppermost cloud layers. This difference in measurements alone shows how close Io’s orbit is to the giant planet. Our moon orbits seemingly a bit closer to Earth at 384,000 kilometers, but the distance from the moon to the highest layers of Earth’s atmosphere is about 376,000 kilometers.
This closeness in proximity has various effects, including on the orbit. For one thing, Io is in a captured rotation. When the moon finishes one orbit of Jupiter, which takes about 42.5 hours, while the moon itself zooms along at 62,000 km/h, it has also turned once around its own axis. Io therefore always faces its planet with the same side. Accordingly, a day on Io lasts 42.5 hours, while its year, which always relates to the sun, corresponds to the Jupiter year of 4,332 Earth days. Io also displays orbital resonances with Europa at 2:1, meaning Io completes two orbits during one by Europa, and with Ganymede at 4:1.
Io ought to have achieved a perfectly circular orbit around Jupiter a long time ago, due to the planet’s strong gravitational pull. But the mass of each of the other moons also exerts force. This results in a slightly unconventional orbit, and is the basis for Io’s strong volcanism.
Io plays a special role in the magnetic field of Jupiter, which is up to 20 times stronger than that of Earth. You might remember from science class that movement within a magnetic field induces electricity. Io thus carries along numerous electrically-charged particles. As an electric generator it can produce up to 400,000 volts, resulting in currents with up to three million amperes. All of these charged particles then distribute themselves in the magnetic field of Jupiter. They expand the field to twice the size it would be witho
ut the presence of Io.
However, the moon pays for this role by having a ton of material per second taken away by Jupiter in this fashion. The magnetic field acts like a particle accelerator for part of the material sent into space by Io, letting it achieve velocities that allow it to leave the Jupiter system. Similar to the way described in the novel, particles the size of grains of dust could indeed start traveling to other planets. In 1992, the Ulysses space probe discovered a stream of such particles emanating from Io.
Io has many siblings—78 are known so far—though new Jupiter moons are being discovered all the time. Together with Europa, Ganymede, and Callisto—all of them ice moons like Enceladus—it is one of the so-called Galilean moons that have been known since 1610. Compared to the ice moons, Io has a relatively low reflection coefficient, or albedo: it reflects only 61 percent of the arriving sunlight.
If you approach Io in a spaceship at an opportune moment, you might even notice a glowing aurora around the moon. It develops when charged particles move along the lines of Jupiter’s magnetic field and then hit the few particles of the very thin atmosphere. This is particularly visible when Jupiter prevents sunlight from reaching the surface of the moon.
The Surface: Glowing and Cold
The surface of Io is unique in the entire solar system. Astronomers have already counted over 400 volcanoes. This makes Io the most geologically active object in the solar system. On true-color images, the face of Zeus’ lover looks poisonous and pockmarked. But these are actually signs of her youth. On a geological scale, Io has the youngest surface of all rocky objects in the solar system, as the surface is on average only a few million years old and areas are being transformed all the time. When you compare photos taken by the Voyager probes with images from Galileo 20 years later, some regions have significantly changed.
Differences in altitude are often balanced out by lava flows, so the surface of this fourth largest moon in the solar system is basically level. But due to tectonic processes, which happen when plates move relative to each other, some mountains with heights of up to 9,000 meters have developed. There is practically no water on Io, but there are lots of other chemicals repeatedly brought to the surface by volcanic activity. Most noticeable are various forms of sulfur.
At minus 143 degrees, the average temperature on Io is very cold. In the event you decide to travel to Io as a tourist, you would absolutely need a spacesuit, as there is no atmosphere to speak of. And you might want to bring along the first part of the Divine Comedy by the Italian poet Dante Alighieri as suitable reading matter. Quite fittingly, many surface features on Io are named after characters and places from his book, Inferno. Once you are outside you can always orient yourself by the position of Jupiter in the sky, as it never changes its location, which is a distinct disadvantage on the side of Io facing away from the planet.
The sun rises in a black sky. According to the positions of the moon and planet, it will cross the firmament once during half an Io orbit, though sometimes it is obscured by Jupiter. On Earth, such solar eclipses are rare, but on Io they occur quite frequently. As long as Jupiter is visible in the sky it never gets quite dark, though the brightness at night is only one-thousandth of that during the day. Earth’s moon manages only one millionth, yet people have the impression they can read a newspaper during nights with a full moon.
Did I say Io has no atmosphere? That is not quite true. Due to volcanic activity, wisps of gas—90 percent of which is sulfur dioxide—cover part of the moon. It creates a pressure that often represents only the billionth part of the pressure in Earth’s atmosphere. During the cold night a portion of the atmosphere freezes and falls, forming a colorful layer on the surface, but after sunrise it is returned to the sky as vapor.
Hiking on Io might be quite amusing, as the gravitational acceleration on its surface is only 1.796 meters per second squared. This is less than a fifth of Earth’s gravity and a bit more than on Earth’s moon. You should be able to perform some nice jumps—at least if you have a comfortable spacesuit. The decisive factor is how deep you can crouch before accelerating upward. If your spacesuit presents no obstacle, jumps to a height of 5 meters are realistic, at least for well-trained people who might jump more than 40 centimeters high on Earth from a standing start. Unfortunately, our technology is not quite ready for this today. You could also compensate for a reduced crouch by using a fast running start.
During your hikes you might come across a few obstacles. You don’t have to worry about sand, or even quicksand as you did on Titan. Io has no weather that would erode rocks into sand. The ground is probably covered by a thin layer of frozen gases. Below it might be another thin layer made up of material that has fallen back to the surface after having been hurled skyward from Io’s frequent volcanic eruptions. The entire surface renews itself so often that the dust simply has no time to accumulate in thicker layers. Due to this fact you will probably be walking across hard volcanic rock most of the time. The rock retains its form, including jagged edges, waiting to be melted down again in the not-too-distant future. You need to be watchful because rock formations created by fractures can have really sharp edges.
What else might impede your progress? As hostile to life as it sounds, Io does not harbor a lot of real dangers. One of them would be the sulfur lakes. Previously it was assumed they were the dominant features on Io. These are surface depressions heated from below like a pan on a stovetop. They contain liquid sulfur. They don’t require very high temperatures, since sulfur melts at 115 degrees. Chemists would find it particularly fascinating to identify all the various allotropes—’allotrope’ is a fancy word for ‘form’—of sulfur that develop under different temperatures and pressures.
The majority of lakes and rivers on Io probably don’t consist of sulfur, but of basaltic lava, which we also know from Earth. However, they are much larger here. Lava lakes like Loki Patera cover several hundred kilometers, and lava streams can reach similar lengths. Here the temperatures reach 500 to 2,000 degrees. It is lucky for you that Io has no atmosphere—first, it doesn’t stink, because there is no air to carry the molecules to your nose, and second, the vacuum does not transfer heat. This would allow you to venture relatively close to hotspots. Io’s lava streams seem to form a thin, hard crust that constantly renews itself. Researchers on Earth have even been able to watch lava waves periodically moving across lava lakes.
There are no volcanoes on Io that resemble those on Earth, though there are similar features. Scientists identified three forms of volcanic activity on existing images.
The first one, the intra-patera eruption, does not occur at the top of a mountain, but within a depression—a patera—that often has steep walls and a flat bottom. It is not clear whether these are created by the collapse of empty magma chambers, like the calderas in volcanoes on Earth, or by hot chambers full of lava melting their way to the surface. The paterae are significantly larger than volcano craters on Earth. On average they measure 41 kilometers and have a depth of about 1,000 meters, while Loki Patera as the largest has a diameter of 200 kilometers. The periodic renewal of the crust might be triggered by solidified lava being higher in density than molten lava and therefore potentially sinking. This would continually mix the lava in the lake.
The second kind of volcanic event on Io is flow-dominated eruptions. Lava streams flow for decades from cracks, fissures, and holes, often at the bottoms of craters and paterae, covering the surrounding area. Active lava streams like Amirani or Masubi are up to 300 kilometers long. They move forward slowly, but steadily. The Prometheus Field, for instance, moved 75 to 95 kilometers between the images taken by Voyager in 1979 and Galileo in 1996. On average, these streams cover 35-60 square meters per second with a one-meter thick layer. In comparison, during eruptions of Hawaii’s Kilauea, lava streams covered only six-tenths of a square meter per second. It is obvious that under these circumstances asteroid-impact craters on Io do not remain visible for long.
More spectacular than eit
her of these first two eruptions is the third type, the explosion-dominated variant, like the one the crew of the ILSE lander dealt with. These short but powerful eruptions can be observed from Earth and make all of Io shine brighter in the infrared spectrum. The strongest observed eruption so far occurred in 2001 at the Surt Patera. Such an event most probably happens when a bubble of particularly hot magma rises from the mantle and reaches a fracture that at some point can no longer withstand the pressure. The pressure builds as the magma gets lighter—less dense—when it heats up, so in a colder environment it has to move upward. The effect is basically the same as shaking a soda bottle and then opening it. The hot lava does not necessarily spurt from a vent. During explosions at Tvashtar Patera in 1999 and in 2007, for instance, a kind of ‘lava curtain’ was formed that reached a height of up to one kilometer along a 25-kilometer-long fracture line. Just imagine! You are standing in front of a 1,000-meter-high wall of glowing lava, a 1,300-degree vertical inferno, that seems to stretch left and right toward the horizon! It will still be there tomorrow, and the day after. Stronger eruptions last up to one week, the weaker ones for months. All of this happens in total silence under a black sky. You can only feel the rumbling of the lava stream below your feet. The eruption blows hot gases far above the lava curtain. This so-called plume reached a height of 330 kilometers during the Tvashtar explosions. The idea that you are standing in front of the entrance to hell would not seem too far-fetched.
Of course, ‘what goes up must come down.’ In the case of the Tvashtar explosions, the contents of the plume were deposited up to 1,200 kilometers away. However, not all the particles return to the surface of Io. With exit velocities of significantly more than one kilometer per second—the velocity of 70 km/s mentioned in the novel has not yet been confirmed—the particles only need a slight push to leave the gravitational field of Io. They receive the additional energy in the form of electrically-charged atoms, called ions, from Jupiter’s magnetic field. Perhaps, although no one has yet landed on the surface of Io to tell us, this effect could be seen in the sky. Some of the particles are sodium ions, which you probably know from those intensely yellow street lights: sodium-vapor lamps. Maybe the electrical energy generated by Io makes the otherwise invisible sodium clouds in its sky glow, at least at night. In telescopic images this glow can be seen whenever Jupiter blocks sunlight from Io.
Ice Moon 2 The Io Encounter Page 25
