by Lucy Hawking
Unfortunately for Terence, they had got very lost and had not managed to find their way back to Tuvalu, where Daisy was now horribly worried about them. The other eco-activists had tried sending out boats to find them, but they had come back with no sighting. Daisy and the others were growing frantic with worry. Surely Terence and his friends didn’t have enough fresh water on the boat to last long, and by day the sun shines very brightly over the South Pacific. During that long night, Daisy had made a call to Florida to ask for help….
In another part of the Solar System, as George pushed himself through the doorway from Mars into the swirling dark orange world beyond, he heard Annie scream: “It’s all wet!’
George landed behind her on what looked like a sloping patch of frozen ground. He wobbled as he landed and reached back to grab hold of the door frame to steady himself. Annie, who George had thrown through the doorway, seemed to fly slowly through the air, landing just next to a channel of dark liquid that flowed into an enormous black lake. For a second it looked like she might topple over and fall into the black stream. But instead, she bent her knees, whirled her arms, and took off, bounding gracefully over the dark river.
George hung on to the door frame. The actual doorway back to Mars had closed behind him, but the portal was still there, shimmering slightly in the dim light. He tested the ground with one space boot. It looked like it was made of solid ice. He tried to chip a bit off with his heel, but it was as solid as granite. George looked around for something else to hold on to once the portal disappeared, but couldn’t reach the rocks behind him and the slope in front was ice all the way down to the mysterious dark river.
“Whatever you do, don’t fall in!” called Annie from the other side of the fast-moving liquid. “We don’t know what’s in it!”
“Where are we?” called George, looking around. The skies above were very low and heavy, full of streaky orange and black clouds. The light was dim, as though it came from some far distant star across many millions of miles of space, and the clouds were so dense that the light struggled to reach the surface of this strange world. “What is this place?”
“I don’t know,” replied Annie. “It feels like Earth before life began. You don’t think Cosmos has sent us back in time by mistake, do you? Maybe he’s transported us back to the beginning, to see what it was like before anything happened.”
While the wind appeared to be blowing gently, in reality it packed a big punch, and George had to hang on to the portal doorway.
“George, this is ground control”—he heard Emmett’s voice, sounding very serious—“Cosmos can’t hold the portal doorway in place for much longer. He needs to shut down that application, otherwise he might start malfunctioning.”
“Annie, what do I do?” asked George, who was suddenly terrified of tumbling into the stream and getting swept into the lake.
“You’ll have to jump,” said Annie. “Like I did!” She was now standing on what looked like a tiny, icy beach on the other side of the channel, where it met the shore of the lake. “It’s flat here so you can land safely.” Beyond the little beach a craggy cliff face overhung the mysterious black lake, its peaks outlined against the glowing tiger-skin sky, like a row of gigantic needles.
“There are too many applications open,” George heard Cosmos say. “Portal will shut down instantly. If this has happened in error, please check the box to send a message to the support unit. Your feedback is important to us.”
The doorway vanished from view, leaving George and Annie by themselves on the mystery planet. Left with nothing to hold on to, George stumbled down the slope toward the black liquid. He pushed off from the ground, just as he had seen Annie do, which sent him upward and across the stream…
“That wind is really strong!” he said, once he’d landed on the other side. All his movements felt as though they were happening in slow motion. “It felt like it was trying to push me over! But it doesn’t seem to be blowing very hard.”
“Maybe it’s a thicker atmosphere than we have at home,” said Annie. “Perhaps that’s why it’s like being in soup rather than being in air. And there’s not much gravity here—that’s why we’re not falling very fast. Oh! What is that?” The clouds had just parted to allow them a view of this extraordinary world. On the other side of the lake, they saw a huge mountain with a dip where the peak should have been.
“Wow! That looks like a dead volcano,” said George.
As they gazed at it, they saw the crater at the top spew out great blobs of bluish liquid.
“I don’t think it’s dead!” shrieked Annie. The thick liquid was moving slowly down through the atmosphere to land on the slopes of the volcano, where it crept along like huge blind sticky earthworms, snaking down the side of the mountain.
“That looks disgusting!” she squeaked. “What is it? And where are we? What planet are we on?”
“You’re not on a planet,” Emmett radioed in finally. “You’re on Titan, the largest moon of Saturn. You are nearly one billion miles away, near to a cryovolcano, Ganesa Macula, which is currently erupting.”
“Is there any danger from the eruption?” asked George. They could see the strange thick lava creeping down channels carved into the rocky landscape.
“Hard to say,” replied Emmett cheerfully, “given that no life-form we know of has ever landed on Titan before.”
“Thanks a lot, Emmett,” said George darkly.
“But the cryovolcanoes emit water—even though it is really cold water. It’s mixed with ammonia, which means it can get down to minus one hundred forty-eight degrees Fahrenheit without freezing. So it probably doesn’t smell very nice. But that won’t bother you, with your space suits on.”
“Emmett, there are lakes here! And rivers!” said Annie. “But they are weird and dark. It doesn’t look like water.’
* * *
TITAN
Titan is the largest of Saturn’s moons and the second largest moon in the Solar System. Only Ganymede—one of Jupiter’s moons—is bigger.
Titan was discovered on March 25, 1655, by Dutch astronomer Christiaan Huygens. Huygens was inspired by Galileo’s discovery of four moons around Jupiter. The discovery that Saturn had moons in orbit around it provided further proof for astronomers in the seventeenth century that not all objects in the Solar System traveled around the Earth, as was previously thought.
Saturn was thought to have seven moons, but we now know there are at least sixty moons in orbit around the giant gas planet.
It takes fifteen days and twenty-two hours for Titan to orbit Saturn—the same time as it takes for this moon to rotate once on its own axis, which means that a year on Titan is the same length as a day!
Titan is the only moon we know of in the Solar System that has a dense atmosphere. Before astronomers realized this, Titan itself was thought to be much larger in mass. Its atmosphere is mostly made up of nitrogen with a small amount of methane. Scientists think that it may be similar to the atmosphere of the early Earth and that Titan could have enough material to start the process of life. But this moon is very cold and lacks carbon dioxide, so the chances of life existing there at the moment are slim.
Titan may show us what conditions on Earth were like in the very distant past and help us understand how life began here.
Titan is the most distant place on which a space probe has landed. On July 1, 2004, the Cassini-Huygens spacecraft reached Saturn. It flew by Titan on October 26, 2004, and the Huygens probe detached from the Cassini spacecraft and landed on Titan on January 14, 2005.
Huygens took photographs of Titan’s surface and found that it rains there!
The probe also observed dry riverbeds—“traces of once-flowing liquid”—on the surface. Cassini imaging later found evidence of hydrocarbons.
In billions of years’ time, when our Sun becomes a red giant, Titan might become warm enough for life to begin!
© NASA/SCIENCE PHOTO LIBRARY
Artwork of the Cassini spacecraft app
roaching Saturn
* * *
“Why has Cosmos sent us here?” asked George.
“Once you and Annie had realized the clue led to one of the moons, Cosmos calculated that Titan was the most probable location for life of some kind to have existed, due to the chemical composition of its structure and atmosphere. Cosmos thinks you will find the next clue on Titan,” Emmett told them. “Although I have to admit, he doesn’t seem to know where. He’s being a bit of a buzzkill at the moment. Sometimes he’s really helpful and then suddenly he starts sulking.”
“Dude. Chill out,” complained Cosmos.
“Ooh, look!” said Annie, pointing toward the lake. “What is it?” Drifting on the tide toward them, they saw a shape like a lifebuoy or a boat.
“It looks like a machine,” said George. “Like something that came from Earth.”
“Unless,” said Annie, “there’s someone here and it belongs to them…Emmett,” she went on slowly, “is there anyone out here? And if there is, do we want to meet them?”
“Um,” said Emmett, “I’m trying to check on Cosmos, to see what he’s got on his files for life on Titan.”
“No,” snapped Cosmos. “I’m tired now. Go away.”
“He’s starting to run low on memory,” said Emmett. “And we’re going to need him to open up the portal to get you back fairly soon. So I’m looking in The User’s Guide instead. Here we are—‘Is There Anyone Out There?’ This should tell us.”
* * *
THE USER’S GUIDE TO THE UNIVERSE
IS THERE ANYONE OUT THERE?
Will some readers of this book walk on Mars? I hope so. Indeed, I think it is very likely that they will. It will be a dangerous adventure and perhaps the most exciting exploration of all time. In earlier centuries, pioneer explorers discovered new continents, went to the jungles of Africa and South America, reached the North and South Poles, and scaled the summits of the highest mountains. Those who travel to Mars will go in the same spirit of adventure.
It would be wonderful to traverse the mountains, canyons, and craters of Mars, or perhaps even to fly over them in a balloon. But nobody would go to Mars for a comfortable life. It will be harder to live there than at the top of Mt. Everest or at the South Pole.
But the greatest hope of these pioneers would be to find something on Mars that was alive.
Here on Earth, there are literally millions of species of life—slime, molds, mushrooms, trees, frogs, monkeys, and, of course, humans. Life survives in the most remote corners of our planet—in dark caves where sunlight has been blocked for thousands of years, on arid desert rocks, around hot springs where the water is at boiling point, deep underground, and high in the atmosphere.
Our Earth teems with an extraordinary range of life-forms. But there are constraints on size and shape. Big animals have fat legs but still can’t jump like insects. The largest animals float in water. Far greater variety could exist on other planets. For instance, if gravity were weaker, animals could be larger and creatures our size could have legs as thin as insects’.
Everywhere you find life on Earth, you find water.
There is water on Mars and life of some kind could have emerged there. The red planet is much colder than the Earth, and has a thinner atmosphere. Nobody expects green goggle-eyed Martians like those that feature in so many cartoons. If any advanced intelligent aliens existed on Mars, we would already know about them—and they might even have visited us by now!
Mercury and Venus are closer to the Sun than the Earth is. Both are very much hotter. Earth is the Goldilocks planet—not too hot and not too cold. If the Earth were too hot, even the most tenacious life would fry. Mars is a bit too cold but not absolutely frigid. The outer planets are colder still.
What about Jupiter, the biggest planet in our solar system? If life had evolved on this huge planet, where the force of gravity is far stronger than on Earth, it could be very strange indeed. For instance, there could be huge balloonlike creatures floating in the dense atmosphere.
Jupiter has four large moons that could, perhaps, harbor life. One of these, Europa, is covered in thick ice. Underneath that there lies an ocean. Perhaps there are creatures swimming in this ocean? To search for them, there are plans to send a robot in a submarine.
But the biggest moon in the Solar System is Titan, one of Saturn’s many moons. Scientists have already landed a probe on Titan’s surface, revealing rivers, lakes, and rocks. But the temperature is about minus 274 degrees Fahrenheit (170 degrees Celsius), at which any water is frozen solid. It is not water but liquid methane that flows in these rivers and lakes—not a good place for life.
Let’s now widen our gaze beyond our Solar System to other stars. There are tens of billions of these suns in our Galaxy. Even the nearest of these is so far away that, at the speed of a present-day rocket, it would take millions of years to reach it. Equally, if clever aliens existed on a planet orbiting another star, it would be difficult for them to visit us. It would be far easier to send a radio or laser signal than to traverse the mind-boggling distances of interstellar space.
If there was a signal returned, it might come from aliens very different from us. Indeed, it could come from machines whose creators have long ago been usurped or become extinct. And, of course, there may be aliens who exist and have big “brains” but are so different from us that we wouldn’t recognize them or be able to communicate with them. Some may not want to reveal that they exist (even if they are actually watching us!). There may be some superintelligent dolphins, happily thinking profound thoughts deep under some alien ocean, doing nothing to reveal their presence. Still other “brains” could actually be swarms of insects, acting together like a single intelligent being. There may be a lot more out there than we could ever detect. Absence of evidence isn’t evidence of absence.
There are billions of planets in our Galaxy and our Galaxy itself is only one of billions. Most people would guess that the cosmos is teeming with life—but that would be no more than a guess. We still know too little about how life began—and how it evolves—to be able to say whether simple life is common. We know even less about how likely it would be for simple life to evolve in the way it did here on Earth. My bet (for what it is worth) is that simple life is, indeed, very common but that intelligent life is much rarer.
There may not be any intelligent life out there at all. Earth’s intricate biosphere could be unique. Perhaps we really are alone. If that’s true, it’s a disappointment for those who are looking for alien signals—or who even hope that some day aliens may visit us. But the failure of searches shouldn’t depress us. It is perhaps a reason to be cheerful because we can then be less modest about our place in the great scheme of things. Our Earth could be the most interesting place in the cosmos.
If life is unique to the Earth, it could be seen as just a cosmic sideshow—though it doesn’t have to be. That is because evolution isn’t over. Indeed, it could be closer to its beginning than its end. Our Solar System is barely middle-aged—it will be six billion years before the Sun swells up, engulfs the inner planets, and vaporizes any life that still remains on Earth. Far-future life and intelligence could be as different from us as we are from a bug. Life could spread from Earth through the entire Galaxy, evolving into a teeming complexity far beyond what we can even imagine. If so, our tiny planet—this pale-blue dot floating in space—could be the most important place in the entire cosmos.
Martin
* * *
“Is there anyone out there?” said Emmett. “I think probably not—at least, not where you are. So far, I think it’s just you and the lakes of methane.”
“Ugh! It’s raining!” said Annie. She held out one hand to catch a raindrop. Huge drops of liquid, three times the size of raindrops on Earth, were falling from the sky. But they didn’t fall fast and straight, like normal rain. They dawdled in the atmosphere, wafting and twirling around like snowflakes.
“Oh no!” said Emmett. “It must be methane rain
! I don’t know how much pure methane your space suits can withstand before they start to deteriorate.”
“Hang on a minute…” George peered at the strange boat that was drifting toward the shoreline.
“Huh!” said Annie, rather sharply. “I am just hanging about. There isn’t much else to do around here.”
“It’s got some writing on it!” said George.
“Ooh, spooky!” Annie leaned forward to get a better look as the huge raindrops splashed gently on her space helmet. “It does too. I can see it now…Well, bonanza!” she said, staring at the round object, which was now marooned on the shore of the lake. “Look at that! It did come from Earth! It’s got human writing on it!”
In big letters on the side of the frozen object they saw the word: HUYGENS.
“Emmett, it says ‘Huygens’ on it,” Annie reported. “What does that mean? It isn’t a bomb, is it?”
“No way!” replied Emmett. “It means you’ve found the Huygens probe—the one they sent to Titan! I don’t think it works anymore, but that’s still pretty cool. Literally cool. Like minus two hundred seventy-four degrees Fahrenheit cool!”
“But that’s not all!” Annie exclaimed. “It’s got some other writing on it too! It’s got alien letters on it!”
On the other side of her, George now had a clear view. “It’s a message in a bottle!” he cried. “Except it isn’t! It’s a message on a probe.”
Painted onto the probe was another row of pictures.
Chapter 11
Back on Earth, Emmett was sitting on the floor in the middle of the Clean Room, with both Cosmos and The User’s Guide to the Universe open in front of him, when he heard a commotion. The cleaning machines at the entry point suddenly whirred into life and a flashing red sign above the door lit up. DECONTAMINATING, it said, beeping loudly as it flashed. Emmett hadn’t noticed the sign on his way in because he was too busy being brushed, buffed, and popped into his white suit by the machine. But he was hardly going to ignore it now. It meant that someone was coming in!