George's Cosmic Treasure Hunt

by Lucy Hawking

  “Can Emmett come up and join you?” asked Susan.

  “Quite literally,” said Annie, “no. He might fall out of one of the brancheroonies and damage his amazing brain cell count. Better stay safely on the ground. Ciao, you guys! George and I are busy.”

  From the tree, they heard Susan sigh. “Why don’t you sit here?” she said to Emmett, arranging a chair for him under the branches. “I’m sure they’ll come down soon.”

  Emmett made a small snuffling noise, and they heard Susan comforting him.

  “Ignore him—he’s a total crybaby!” Annie whispered to George. “And don’t start feeling sorry for him—that’s lethal. The minute you show weakness, he pounces. I felt sorry for him the first time he cried. And then he bit me. My mom’s too sappy—she just can’t see it.”

  Susan’s footsteps tapped away into the house.

  “Okay, hold on to that branch,” ordered Annie, “in case you faint away in shock at what I have to tell you.”

  “What is it?” said George.

  “Huge news,” confirmed Annie. “So huge-ously huge, your bottom will fall through your pants in surprise.” She looked at him expectantly.

  “Well, tell me,” said George patiently.

  “Promise you won’t think I’ve gone bananas?”

  “Um, well, I pretty much thought you were already,” admitted George. “So that won’t change anything.”

  Annie swatted him with her free hand.

  “Ouch!” he said, laughing. “That hurt.”

  “George, are you okay?” came a little voice from below. “Do you need protection from the renegade one? She can be really evil.”

  “Shut up, Emmett!” Annie shouted down. “And stop listening to our conversation.”

  “I’m not trying to listen!” came Emmett’s high-pitched whine. “It’s not my fault that you’re sending a stream of useless vibrations into the atmosphere.”

  “Then go somewhere else!” yelled Annie.

  “No!” said Emmett obstinately. “I’m staying here in case George needs my superintelligent assistance. I don’t want him to waste his bandwidth on your rudimentary communication.”

  Annie rolled her eyes up to heaven and sighed. She inched along the branch toward George and whispered in his ear: “I’ve had a message from aliens.”

  “Aliens!” said George loudly, forgetting about Emmett below. “You’ve had a message from aliens!”

  “Shush!” said Annie frantically. But it was too late.

  “Does the young female humanoid really believe that a life-form intelligent enough to send a message across the vast expanse of space would pick her to receive it?” said Emmett, standing up and looking into the tree. “And anyway, there are no aliens. We have no proof of another intelligent life-form in the Universe at this moment. We can only calculate the probability that on some other planets, there are conditions suitable for forms of extremophile bacteria. Which would have the approximate IQ level of Annie herself. Or probably a bit more. I can calculate the probability of intelligent life for you, if you like, using the Drake Equation.’

  * * *

  THE DRAKE EQUATION

  The Drake Equation isn’t really an equation. It’s a series of questions that help us to work out how many intelligent civilizations with the ability to communicate there might be in our Galaxy. It was formulated in 1961 by Dr. Frank Drake of the SETI Institute, and is still used by scientists today.

  This is the Drake Equation:

  N = N* x fp x ne x fl x fi x fc x L

  N* represents the number of new stars born each year in the Milky Way Galaxy

  * * *

  Question:

  What is the birthrate of stars in the Milky Way Galaxy?

  Answer:

  Our Galaxy is about twelve billion years old, and contains roughly three hundred billion stars. So, on average, stars are born at a rate of three hundred billion divided by twelve billion, equaling twenty-five stars per year.

  fp is the fraction of those stars that have planets around them

  * * *

  Question:

  What percentage of stars have planetary systems?

  Answer:

  Current estimates range from 20% to 70%.

  ne is the number of planets per star that are capable of sustaining life

  * * *

  Question:

  For each star that does have a planetary system, how many planets are capable of sustaining life?

  Answer:

  Current estimates range from 0.5 to 5.

  fl is the fraction of planets in ne where life evolves

  * * *

  Question:

  On what percentage of the planets that are capable of sustaining life does life actually evolve?

  Answer:

  Current estimates range from 100% (where life can evolve, it will) down to close to 0%.

  fi is the fraction of habitable planets with life where intelligent life evolves

  * * *

  Question:

  On the planets where life does evolve, what percentage evolves intelligent life?

  Answer:

  Estimates range from 100% (intelligence has such a survival advantage that it will certainly evolve) down to near 0%.

  fc is the fraction of planets with intelligent life capable of interstellar communication

  * * *

  Question:

  What percentage of intelligent races have the means and the desire to communicate?

  Answer:

  10% to 20%.

  L is the average number of years that a communicating civilization continues to communicate

  * * *

  Question:

  How long do communicating civilizations last?

  Answer:

  This is the toughest of the questions. If we take Earth as an example, we’ve been communicating with radio waves for less than one hundred years. How long will our civilization continue to communicate with this method? Could we destroy ourselves in a few years, or will we overcome our problems and survive for ten thousand years or more?

  When all of these variables are multiplied together, we come up with:

  N, the number of communicating civilizations in the galaxy.

  * * *

  “Well, thanks for that, Professor Emmett,” said Annie. “Your Nobel Prize is in the mail. So now why don’t you bacteria off yourself? Go find some of your own species to hang out with? Actually, George, there are aliens on Earth, and Emmett is one of them.”

  “No, no, rewind,” said George urgently. “You’ve had a message from some aliens? Where? How? What did it say?”

  “They sent her a text message to say they would be beaming her up to the mother ship at twenty-one hundred hours,” said Emmett. “We live in hope.”

  “Shut up, Emmett.” This time it was George’s turn to feel annoyed. “I want to hear what Annie has to say.”

  “Okay, here’s the scoop!” said Annie. “Settle down, friends and aliens, and prepare to be amazed.”

  Below them, Emmett was hugging the tree in an attempt to get closer to them.

  George smiled. “I’m prepared, agent Annie,” he said. “Go for it.”

  “My amazing story,” began Annie, “starts one ordinary evening when no one could have predicted that for the first time ever in the history of this planet we would finally hear from an ET.

  “Me, my family, and I—,” she continued grandly.

  “And me!” squeaked Emmett from below.

  “And him,” she added, “had just come back from watching a robot land on Mars. Just your everyday family outing. Nothing special. Except that…”

  A few weeks back, Eric, Susan, Annie, and Emmett had gone to the Global Space Agency to watch a new type of robot attempt to land on the red planet. The robot, Homer, had taken nine months to travel the 423 million miles to Mars. He was the latest in a series of robots sent by the agency to explore the planet.

  Eric was very excited about Homer touch
ing down on Mars because he had special equipment on board that would help him find out whether there had ever been any life on our nearest neighbor. Homer would be looking for water on Mars: Using a special scoop at the end of his long robotic arm, he would scrabble through the icy surface of Mars to pick up handfuls of mud, which he would then bake in a special oven. As Homer heated up the samples of soil, he would be able to discover whether Mars, now a cold desert planet, had once, in its distant, warmer, wetter past, been flowing with water.

  * * *

  ROBOTIC SPACE TRAVEL

  A space probe is a robotic spacecraft that scientists send out on a journey across the Solar System in order to gather more information about our cosmic neighborhood. Robotic space missions aim to answer specific questions such as: “What does the surface of Venus look like?” “Is it windy on Neptune?” “What is Jupiter made of?”

  While robotic space missions are much less glamorous than manned spaceflight, they have several big advantages:

  Robots can travel for great distances, going much farther and faster than any astronaut. Like manned missions, they need a source of power: Most use solar arrays that convert sunlight to energy, but others traveling long distances away from the Sun take their own onboard generator. However, robotic spacecraft need far less power than a manned mission, as they don’t need to maintain a comfortable living environment on their journey.

  Robots don’t need supplies of food or water, and they don’t need oxygen to breathe, making them much smaller and lighter than a manned spacecraft.

  Robots don’t get bored or homesick or fall ill on their journey.

  If something goes wrong with a robotic mission, no lives are lost in space.

  Space probes cost far less than manned spaceflights, and robots don’t want to come home when their mission ends.

  Space probes have opened up the wonders of the Solar System to us, sending back data that has allowed scientists to far better understand how the Solar System was formed and what conditions are like on other planets. While human beings have, to date, traveled only as far as the Moon—a journey averaging 234,000 miles (376,000 kilometers)—space probes have covered billions of miles and shown us extraordinary and detailed images of the far reaches of the Solar System.

  In fact, almost thirty space probes reached the Moon before mankind did! Robotic spacecraft have now been sent to all the other planets in our Solar System, they have caught the dust from a comet’s tail, landed on Mars and Venus, and traveled out beyond Pluto. Some space probes have even taken information about our planet and the human race with them. Probes Pioneer 10 and 11 carry engraved plaques with the image of a man and a woman on them and also a map, showing where the probe came from. As the Pioneers journey onward into deep space, they may one day encounter an alien civilization!

  The Voyager probes took photographs of cities, landscapes, and people on Earth with them, as well as a recorded greeting in many different Earth languages. In the incredibly unlikely event of these probes being picked up by another civilization, these greetings assure any aliens who manage to decode them that we are a peaceful planet and we wish any other beings in our Universe well.

  There are different types of space probes, and the type used for a particular mission will depend on the question that the probe is attempting to answer. Some probes fly by planets and take pictures for us, passing by several planets on their long journeys. Others orbit a specific planet to gain more information about it and its moons. Another type of probe is designed to land and send back data from the surface of another world. Some of these are rovers, others remain fixed wherever they land.

  The first rover, Lunokhod 1, was part of a Russian probe, Luna 17, which landed on the Moon in 1970. Lunokhod 1 was a robotic vehicle that could be steered from Earth, in much the same way as a remote control car.

  NASA’s Mars landers, Viking 1 and Viking 2, which touched down on the red planet in 1976, gave us our first pictures from the surface of the planet, which had intrigued people on Earth for millennia. The Viking landers showed the reddish-brown plains scattered with rocks, the pink sky of Mars, and even frost on the ground in winter. Unfortunately, it is very difficult to land on Mars, and several probes sent to the red planet have crashed onto the surface.

  Later missions to Mars sent the two rovers, Spirit and Opportunity. Designed to drive around for at least three months, they lasted for far longer and also, like other spacecraft sent to Mars, found evidence that Mars had been shaped by the presence of water. In 2007, NASA sent the Phoenix Mars Mission. Phoenix could not drive around Mars, but it had a robotic arm to dig into the soil and collect samples. It had an onboard laboratory to examine the soil and work out what it contains. Mars also has three operational orbiters around it—the Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter, showing us in detail the surface features.

  Robotic space probes have also shown us the hellish world that lies beneath the thick atmosphere of Venus. It was once thought that dense tropical forests might lie under the Venusian clouds, but space probes have revealed the high temperatures, heavy carbon dioxide atmosphere, and dark brown clouds of sulfuric acid. In 1990 NASA’s Magellan entered orbit around Venus. Using radar to penetrate the atmosphere, Magellan mapped the surface of Venus and found 167 volcanoes more than seventy miles wide! ESA’s Venus Express has been in orbit around Venus since 2006. This mission is studying the atmosphere of Venus and trying to find out how Earth and Venus developed in such different ways. Several landers have returned information from the surface of Venus, a tremendous achievement given the challenges of landing on this most hostile of planets.

  Robotic space probes have braved the scorched world of Mercury, a planet even closer to the Sun than Venus. Mariner 10, which flew by Mercury in 1974 and again in 1975, showed us that this bare little planet looks very similar to our Moon. It is a gray, dead planet with very little atmosphere. In 2008 the MESSENGER mission returned a space probe to Mercury and sent back the first new pictures of the Sun’s nearest planet in thirty years.

  Flying close to the Sun presents huge challenges for a robotic spacecraft, but probes sent to the Sun—Helios 1, Helios 2, SOHO, TRACE, RHESSI, and others—have sent back information that helped scientists to develop a far better understanding of the star at the very center of our Solar System.

  Farther away in the Solar System is Jupiter, first seen in detail when the probe Pioneer 10 flew by in 1973. Pictures captured by Pioneer 10 also showed the Great Red Spot in great detail, a feature seen through telescopes from Earth for centuries. After Pioneer, the Voyager probes revealed the surprising news about Jupiter’s moons. Thanks to the Voyager probes, scientists on Earth learned that Jupiter’s moons are all very different from one another. In 1995 the Galileo probe arrived at Jupiter and spent eight years investigating the giant gas planet and its moons. Galileo was the first space probe to do a flyby past an asteroid, the first to discover an asteroid with a moon, and the first to measure Jupiter over a long period of time. This amazing space probe also showed the volcanic activity on Jupiter’s moon, Io, and found Europa to be covered in thick ice, underneath which may lie a gigantic ocean that could even harbor some form of life!

  NASA’s Cassini was not the first to visit Saturn—Pioneer 11 and the Voyager probes had flown past on their long journey and sent back detailed images of Saturn’s rings and more information about the thick atmosphere on Titan. But when Cassini arrived in 2004 after a seven-year journey, it showed us many more features of Saturn and the moons that orbit it. Cassini also released a probe, ESA’s Huygens, which traveled through the thick atmosphere to land on the surface of Titan. The Huygens probe discovered that Titan’s surface is covered in ice and that methane rains down from the dense clouds.

  Voyager 2 flew by Uranus, even farther from Earth, and showed pictures of this frozen planet, tilted on its axis! Thanks to Voyager 2, we also know much more about the thin rings circling Uranus, which are very different to the rings of Saturn, as
well as many other details of its moons. Voyager 2 carried on to Neptune and revealed this planet is very windy—Neptune has the fastest moving storms in the Solar System. Voyager 2 is now ten billion miles from Earth and Voyager 1 is eleven billion miles away. They should be able to continue communicating with us until 2020.

  The Stardust mission, during which a probe caught particles from a comet’s tail and returned them to Earth in 2006, taught us far more about the very early Solar System from these fragments. Capturing these samples from comets, which formed at the center of the Solar System but have traveled to its very edge, has helped scientists to understand more about the origin of the Solar System itself.

  * * *

  “Where there is water,” Eric had told the kids, “as we know from our planet Earth, there could be life!”

  Even more important, Homer was to help prepare for a mission to Mars, which would take human beings to a new planet. For the first time ever, the Global Space Agency was getting ready to send a spacecraft with people on board to explore Mars and see if it would be possible to start a colony out there.

  So Homer mattered a lot—not just because he was expensive or had fancy technology or, as Annie put it, looked like he had a personality, with his beady little camera eyes, stick legs, and round tummy where the onboard oven lived.

  Homer mattered because he was the first step into space for the human race—he was the front-runner for a whole new type of space exploration that might lead to people living on another planet.

  On the day of Homer’s descent to the red planet, the big round control room was crammed with people eagerly reading the information from the banks of computer screens. As Homer traveled, he sent back signals to Earth with progress reports. These arrived at the Global Space Agency in code, which the terrestrial computers then turned into words and pictures. Because of the time it took for Homer’s signal to reach Earth, in the control room they were only discovering now what had happened on Mars. Had Homer landed—or had he crashed? They were about to find out.