“Poor you, Dad,” sympathized Annie. “I know just how you feel. Have a hug!”
There was a moment’s silence as Eric and Annie hugged and George stood around wondering what to do next. And that’s when he had his new idea.
“I know!” he exclaimed. “I’ve got a plan! It’s like a thing we did before: we opened the portal with Cosmos but we didn’t go through it—we just looked! It was way more exciting than watching stuff on YouTube because it was real! Could we do that? Could Cosmos just show us something, rather than let us actually travel?”
“Aha!” Eric’s eyes brightened up. “Now that may well be within the bounds of possibility!”
“Like, in other words, yes?” said Annie.
“Cosmos?” asked Eric. “Can you show us a space voyage, even if you can’t let us physically transport to the location we choose?”
Cosmos tutted to himself while he checked his operating rules. “I find that I can!” he cried, clearly unhappy to have blocked his friends earlier. “What would you like to view?”
Annie and George went into a huddle together.
“What do you want to see?” George asked Annie eagerly.
“Well, I really don’t want to just look through the portal,” admitted Annie. “I won’t feel like I’ve left everything behind if we’re stuck on this side of the doorway.”
“Maybe just knowing that space is out there—because you can see it for real, in 3-D, and sort of feel it and touch it—will make you happier,” said George hopefully, trying to persuade her.
“Maybe,” said Annie. But she looked doubtful.
“I think we should look at a place in our solar system, so it’s somewhere we could maybe visit one day,” said George. “Then you can imagine stepping through the space doorway and crunching down onto the surface of another planet and it will be sort of like going there for real.”
“Oooh, yes,” said Annie, brightening. “That’s a cool idea.”
“What about one of Jupiter’s moons?” George suggested. “They’re super-icy and weird and strange—and who knows what we might see!”
“It’s a plan,” said Annie decisively. “I know! I know!” She jumped up and down, squeaking suddenly. “When we got the VR thingy, I did some research on marine life—and I found out that there might be extraterrestrial aliens swimming around under the icy crust on Europa! Let’s go and see for ourselves.”
“Oh, yeah,” said George. “Now that would be awesome.” He thought back to the VR headset and the views he had seen of the underwater world around the Great Barrier Reef. Could it look like that in space too?
“Yay! Dolphins in space!” said Annie. “Can we, Dad? Can we?”
“Well, it’s cheaper than a trip to the aquarium,” said Eric cheerfully. “But don’t expect to actually see dolphins, mind you. We don’t really know whether there are any beings anything like dolphins or minke whales in space, you know.”
“Then let’s find out!” said Annie.
“Permission granted,” said Cosmos. “Security checking …”
This was a new phase in Cosmos’s space doorway creation activity, which Eric himself had added after Cosmos had been hacked by an evildoer called Alioth Merak, who had turned their friendly supercomputer into a dangerous enemy.
“Security check complete!” Cosmos sang out. “Prepare portal.”
“Cosmos,” said Eric, as the now-familiar twin beams of light shot out from the little computer and started to draw a door shape in the air. “Make sure you add a radiation shield to protect us, given how close to Jupiter we will be.”
“Affirmative,” replied Cosmos, who had gone into operational mode, during which time he tended to become more automatic than personable.
George threw a glance over at Annie’s tablet computer and noticed that the outgoing messages, made up of chunks of text taken from some of the greatest scientific books, were still pouring relentlessly onto the screen. “Your ‘friend,’ ” he said, using his fingers to make air quotes, “must be going crazy by now.”
“Hope so!” said Annie crossly. “Just the other day, she was telling me how she was, like, my BFF. And that she wasn’t taking part in all the mean stuff happening at school. But then it turns out that she’s worse than all the others! I bet she was sending those messages to impress the bullies. But she didn’t dare admit to me that she couldn’t be my friend anymore, so she was pretending to me as well… .”
“Look,” said George, pointing. The hairs on his neck stood on end. “Cosmos is opening the portal!”
The doorlike shape, which Cosmos had drawn out of beams of light, had now turned solid and was swinging very slowly open. All three of them—Eric included—watched with open mouths as the door opened fully, to reveal behind it the pitted and cracked icy surface of one of Jupiter’s moons. It was a sight that never disappointed.
“Wow! Could we skate on Europa?” asked Annie in a breathless voice as she gazed through the portal doorway at the rough, icy landscape beyond. The view stretched all the way to the horizon, peaceful and calm—just an uninhabited ice-bound celestial body in orbit around its planet, Jupiter. From Europa, the two friends and Eric could see the magnificent gas planet hanging in the sky like a massive stripy ball. The light was dim on Europa, this moon world being so much farther away from the brilliance of the Sun than the Earth, but they could still see strange ridged and squiggly formations in the ice. With a gentle pfoof in the air, as though the moon was doing a tiny exhale, a burst of gassy liquid escaped upward from the crusty surface into the thin atmosphere. Against the black backdrop of space—peppered with billions of tiny stars in every direction—the fountain made a lacy pattern as it froze and fell back down to the surface in gentle flakes.
“Ooh, it’s just like when we were on Enceladus!” said Annie happily. Her father was looking at her quizzically, but she carried on regardless.
George started coughing very loudly to try and drown out what she was saying—he just knew this wasn’t the time to let her father know they’d been on unauthorized space voyages in the recent past—like that particular trip to Enceladus, one of Saturn’s moons.
But Annie just patted him on the back and carried on talking over his volley of splutters. “Only this time, we’re all snug at home, not standing on a volcano that’s about to erupt under us—” She realized her mistake too late and fell silent.
George stopped coughing and gave her a puce-faced glare. He couldn’t believe she had been so stupid! Annie just shrugged back at him again.
“When did you go to Enceladus?” demanded her father. “There are some unaccounted space voyages in the supercomputer log, and if it turns out that it was you all along …”
“We went to Enceladus in our minds,” Annie lied, crossing her fingers behind her back. She and George had, in fact, visited that weird little billiard ball of a moon on a secret mission to collect the building blocks of life. It had been an unhappy and dangerous visit and they had been desperate to escape, especially when a cryovolcano had nearly exploded through a fault line under their feet.
“You know, Dad,” Annie continued, “you’re always saying, ‘I travel across the Universe in my mind!’ Well, we’ve been doing that too. And it’s really great. You were right all along.”
Her father gave her a disbelieving look. George stared hard at Europa through the doorway. He knew if he glanced at Eric he’d look guilty and give the game away, so he searched the surface of the moon instead. He hoped to spot something to ask Eric about in order to make the tricky moment go away. And just as he was trying to form a clever question about the gravity there, or the orbit of Europa, or the possibility of alien life, he saw something for real.
“What’s that?” he said, pointing.
“What’s what?” said Eric, peering through the doorway. “What have you seen?”
“Over there,” said George. “There’s a hole in the ice!”
“I expect there are lots of holes in the ice,” said Annie,
confused as to why George was suddenly sounding so excitable. “That’s how the geysers escape from the underwater ocean.”
“Not like that one!” he said.
Annie gazed in the direction of his outstretched finger and saw exactly what he meant. “OMG!” she breathed. George had indeed spotted a hole in the crinkly, greenish-white ice, but it wasn’t just any hole. It was perfectly round, as though someone had taken a cookie cutter and sliced out a circle of thick ice. “Could that happen naturally?” she asked her dad.
Eric was staring in horror at George’s discovery. “No,” he said, shaking his head. “I don’t believe it could. That’s not the effect of an impact. That looks like it was done mechanically.”
“Mechanically?” said Annie. “Like, by a robot?”
“But there are no missions to Europa,” said George, who knew his solar system pretty well by now. “We’ve never sent a robot mission to Europa—just a space probe flying past—so how could a machine have made that hole?”
“Cosmos,” said Eric. “Give me the coordinates of the area we can see on Europa right now.” Obligingly, Cosmos flashed up on his screen a string of numbers, which Eric read quickly. “Yes, yes, yes,” he muttered to himself. He looked back at the hole in the ice completely baffled.
“What is it, Dad?” asked Annie.
“The coordinates are right, they fit the location, but this shouldn’t happen for years yet …” Eric wasn’t really making sense to the two friends.
“What shouldn’t happen?” asked George.
“Artemis,” replied Eric. “This is the location and the plan for Artemis … but Artemis hasn’t happened yet. I don’t understand. This is literally impossible.”
“What is Artemis?” asked Annie.
But Eric was already busy, closing down the portal doorway by tapping commands on Cosmos’s keyboard. “I have to go,” he said distractedly. “I have to—” He was already halfway out of the door.
“Where?” Annie called after him. “Where are you going?”
But it was too late—her father had already disappeared.
EUROPA
Is there really life on Europa, the “blue” moon of Jupiter? Right now, we don’t know! Thanks to the Galileo mission, launched in 1989, which sent back lots of new information about Jupiter’s fourth-largest moon, we think there is a subsurface ocean under the thick icy crust, which could contain a form of life. But whether we would actually find dolphins swimming about if we could land on Europa and drill down through the several-miles-thick carpet of ice, is anyone’s guess! It would be far more probable—and actually, equally exciting to scientists—that any life found would be more like microbes.
But we may get some clearer answers in the next decade! A new mission called JUICE (Jupiter Icy Moon Explorer) is planned to set off in 2022 to take a closer look at this mysterious moon. JUICE is a robotic spacecraft designed by the European Space Agency. It will take around eight years to reach Jupiter, arriving in 2030, and will spend about three years looking at the giant gas planet and three of its largest moons, Callisto, Ganymede, and Europa. Hopefully JUICE and a simultaneous NASA mission, Europa Clipper, will tell us much, much more about Europa.
What do we know now?
Well, we know that:
Europa is an icy moon in orbit around Jupiter, the largest planet in our solar system.
Jupiter has a total of 67 moons, but the four largest of them—including Europa—are called the Galilean moons, because they were discovered in 1610 by the astronomer Galileo Galilei. When Galileo spotted these moons orbiting around Jupiter, he realized that not everything in the solar system went around the Earth, as previously thought! This completely changed perceptions of our place in the solar system and the Universe itself.
Europa is only slightly smaller than our Moon but has a much smoother surface. In fact, Europa may have the fewest lumps and bumps of any object in the solar system as it doesn’t seem to have mountains or craters!
It has an icy crust surface. Scientists believe the ocean underneath could be 100 kilometers—or 62 miles—deep. Compare this to the deepest ocean on Earth—the Marianas Trench in the Pacific Ocean, which is 6.8 miles deep!
The crust has distinctive markings in the form of dark stripes, which may be ridges formed by eruptions of warm ice at an earlier stage in Europa’s life.
Volcanoes on Earth, in our Solar System, and Beyond by Professor Tamsin A. Mather
Imagine what it would be like to visit an erupting volcano. Perhaps you even have? The ground shakes with tiny earthquakes as molten lava forces its way from the Earth’s insides and hums as volcanic gases struggle to escape. Booming explosions vibrate through your body and ears. Acid fumes sting your eyes and nostrils, and even your skin and sweat begin to smell of sulphur (a mix of rotten eggs and struck matches). Up ahead, red-hot rocks fly high into the air, turning black as they cool and plummet to the ground. Some of them join the growing cone of rubble. Others feed a lava flow that snakes, clinking and fuming, downhill. This is what it was like for me visiting Mount Etna in Sicily in 2006. It was actually quite a small eruption (otherwise it would not have been safe to get so close!), but breathtaking, even for a volcano scientist (known as a volcanologist).
To get volcanoes on any planet, you need a source of heat and something to melt. On Earth the heat is its inner heat (mainly left over from its birth and from ongoing radioactive decay within its rocks). The “something to melt” is Earth’s rocky mantle, the layer of rock under the thin outer crust that we live on. It is mainly solid, but hot enough that it can flow slowly, or creep, a bit like a very sticky liquid. It gets hotter as you go deeper, from a thousand degrees Fahrenheit (a bit hotter than your oven) to over 7200°F (for comparison, the surface of the Sun is about 9939°F) just before you reach the molten outer core. Pressure also increases as you go deeper inside the Earth, like an exaggeration of the pressure you feel when you dive to the bottom of a swimming pool.
So the mantle is already very hot, but it is solid. On Earth there are two ways that nature melts it. In some places, like Iceland, where tectonic plates split apart from each other, or beneath Hawaii, where blobs of deep, hot mantle flow slowly upward like a lava lamp, the pressure on the mantle decreases. This makes the mantle’s melting point drop. You might have seen how kettles boil at a lower temperature up a mountain as pressure drops. In other places, like under Japan and Indonesia, things get added to the mantle and make it melt, just as we add salt to roads and sidewalks in winter to melt ice. This happens at “subduction zones” where two tectonic plates push together. One sinks below the other and into the mantle, releasing water and other stuff into the mantle rocks above.
When the mantle melts, it produces a liquid rock called magma. This magma is less dense than the surrounding rock, and so it starts to move up toward the surface. This journey can be relatively quick, especially beneath the oceans where Earth’s crust is thin. Or it can be longer, especially where the crust is thicker, like on the continents. The longer this journey takes, the more time the magma has to cool and change, becoming stickier and stickier.
But what makes magma explode out of the ground rather than just oozing like jam out of a doughnut? Magma has gases like steam and carbon dioxide dissolved in it. As magma rises and the pressure drops, the gases can’t stay dissolved and they form bubbles. As they rise further, these bubbles grow bigger and bigger until they reach the surface and sometimes explode. Something similar happens when you open a bottle of cola quickly, especially if someone has been kind enough to shake the bottle first! Sticky magmas are better at trapping gas bubbles. This is one of the reasons why some volcanic eruptions are much more explosive than others.
That’s how we explain most volcanism on Earth. But Earth is not the only place in our solar system that has volcanoes. Just look at a full Moon on a clear night. The large, dark patches you can see are solidified lava beds. They are called Mare, from the Latin word for sea, because early astronomers thought they r
eally were seas.
On Mars there are huge volcanoes, including Olympus Mons, the largest known volcano (over 13 miles high and about the size of Arizona).
Being smaller bodies than the Earth, both our Moon and the planet Mars cooled more quickly, so their volcanoes are now dead. Venus is a similar size to Earth, and the latest results from the Venus Express mission show exciting new evidence of possible active lava flows on this planet.
Farther out in the Solar System we see more exotic forms of volcanism on moons orbiting the giant gas planets. The planet Jupiter has volcanoes on several of its more than 60 confirmed moons. Io, the innermost of the planet’s larger moons, is the most volcanically active body we know of in the Solar System. Io heats up—like a squash ball in your hand—as it is stretched and squeezed under immense tidal forces from the giant planet it orbits. Io’s volcanoes are spectacularly alive, sending plumes of gas and dust hundreds of miles into space. Europa, Jupiter’s ice-covered moon, is also of great interest. It has a very young surface, with very few craters. This suggests that ice volcanism is continually covering the surface with watery magmas.
In 2005 the Cassini space probe spotted fountains of vapor and ice shooting into space from one of Saturn’s moons, Enceladus. And even farther away from the Sun, the Voyager 2 space probe saw dark plumes rising high above one of Neptune’s moons, Triton, maybe made of nitrogen ice and driven by heat from the distant Sun itself.
Recent discoveries of rocky planets outside our solar system mean that whole new types of volcanism might also exist in the Universe that we and scientists of the future—like you perhaps—have yet to discover. Light that reaches Earth from these planets can hold clues about their atmospheres. As volcanoes release distinctive gases, volcanism could be the first geological process that we confirm outside our solar system.
I am often awestruck by how much remains to be understood about volcanoes on our own planet. The idea of a whole universe of volcanism still out there to explore is mind-boggling!
George and the Blue Moon Page 3
