The Aliens Are Coming!

by Ben Miller

  One look at the Chicxulub crater in the Yucatán Peninsula will tell you that comets are bad news. That particular impact wiped out the dinosaurs, and we have Jupiter to thank for the fact that such Armageddons are relatively rare events. Basically, the bully planet’s strong gravity hoovers up anything dodgy that the outer solar system throws our way. Incredibly, in 1993 we actually saw this in action when the comet Shoemaker–Levy was spotted orbiting Jupiter, disappearing in a spectacular collision just over a year later.5

  In truth, none of these arguments have really gone away. Intelligent life may be rare. After all, if our nearest neighbors are in the next galaxy, rather than in the next star system, that goes a long way toward explaining the Fermi Paradox. Nevertheless, we have some cause for hope. Not everyone believes that a flip-flopping north pole would be a disaster, for example; and there are arguments that, while Jupiter protects us from comets, it wreaks havoc in the asteroid belt. But by far the most encouraging evidence has come from the Kepler Space Telescope; in short, the size and orbit of the Earth aren’t nearly as rare as we might have feared. In fact, they are decidedly run-of-the-mill.

  PLAYING WITH A LOADED DECK

  It turns out that back in the nineties and noughties, the method we had for finding planets relied on them being big. Called the radial velocity method, it basically relied on detecting planets via gravitational effects. As a large planet orbits a star, it causes that star to wobble, and the wobble affects the frequency of the light that the star gives out. If you analyze the way that the star’s light changes frequency you can work out how fast it is wobbling, and once you know that you can then work out the mass of the planet and the size of its orbit.

  All very clever, but the only planets you can detect tend to be large ones. Small rocky planets like the Earth don’t cause their home stars to wobble, or at least the wobble is so small that it hardly affects the star’s light and so is very hard to measure. To find out whether there were any Earthlike planets out there, we needed a new telescope. And in 2009, that’s where NASA’s Kepler mission came in.

  THE MAN IN THE MIRROR

  It’s truly fitting that the Kepler Space Telescope is named after Johannes Kepler, the seventeenth-century German astronomer. Not only did he invent the modern refracting telescope,6 beloved by amateur astronomers the world over, but he also placed an important foundation stone upon which we built our understanding of planetary motion. Using observations made by the Danish astronomer Tycho Brahe, Kepler proposed that the planets’ orbits aren’t circular, as had been believed since the time of Plato, but elliptical. What’s more, he claimed that the planets’ speeds aren’t constant, as had also been believed since the time of the Ancient Greeks, but vary according to where they are in their orbit. One of the crowning achievements of Newton’s Principia was that he was able to show that his Law of Universal Gravitation, when applied to the Sun and planets, produced all the effects proposed by Kepler.

  The optical telescope that bears Kepler’s name is a spectacular beast. As the name suggests, it is far from earthbound; it was launched into space on a three-stage rocket into a heliocentric, or Sun-centered, orbit. The advantages of being up in space are several: For a start, the atmosphere blurs starlight, which is why the stars twinkle, and, secondly, you don’t have to wait for it to get dark to be able to use it. The business end points north, so that it never catches the Sun, and looks at a small area of the sky on the edge of the constellation of Cygnus, the Swan. I say small; within that area it monitors the brightness of some 145,000 stars.

  Kepler uses what’s called a transit method to detect planets. Put simply, it looks at the light coming from a given star, and if it sees a dip in brightness, it knows a planet is crossing, or, to use the jargon, transiting. Needless to say, it’s very sensitive, as it’s looking for something like the drop in brightness of a fruit fly passing across a car headlight. By measuring exactly how much light is blocked, it can work out how big the planet is, and by measuring the time between transits it can work out how large the orbit is and how hot the planet must be.

  The results have been astonishing. To date, Kepler has turned up over one thousand planets, with over three thousand prime suspects awaiting confirmation. And what have we discovered? Well, hindsight is a wonderful thing, but in many ways it’s obvious: Big and small planets are less common than medium-sized ones. In other words, most planets appear to be between Earth and Neptune in size. Smaller planets like Earth, and big ones like Jupiter, are plentiful, but not quite so abundant.

  As a result, we now believe our own solar system is something of an outlier. For a start, Jupiter-sized planets are unusual, and tend to be hot rather than cold like ours. Secondly, we don’t have that many medium-sized planets. And, lastly, there’s nothing inside Mercury’s orbit, whereas many of the systems found by Kepler have planets of all kinds in orbits of ten days or fewer.7 That said, the solar system’s not exactly rare: We currently think the odds of a cold Jupiter are something like one in a hundred. With 200 billion stars in the Milky Way, that still leaves around two billion planetary systems similar to our own.

  When it comes to Earthlike planets, the Kepler data is also encouraging. The latest estimate is that over one in five Sun-like stars have an Earth-sized planet in their habitable zones, implying the nearest wet rocky planet might be as little as twelve light-years away.8 Although Kepler stopped making measurements in 2013, we are still sifting through the mountains of data it produced, and finding more and more small rocky planets in the habitable zones of stars like our very own Sun.

  The problem with Kepler, of course, is that to maximize its chances of success it was pointed toward a distant but dense clump of stars. That means that all the Earthlike planets we have found so far are well out of the range of even our most advanced telescopes. Kepler 186f, for example,9 is a rocky planet roughly the same size as the Earth orbiting its home star at the right distance to have water on its surface. All right, that home star happens to be an M-type rather than a G-type like our own Sun—a “red dwarf” to you and me—and such stars are prone to scorching solar flares.10 But Kepler 186f happens to be at the outer edge of its star’s habitable zone, just out of harm’s way. And that means it may be suitable for life.

  SETI, of course, wasted no time in pointing a radio telescope at Kepler 186f, and searching up and down the dial for anything that looked suspicious. They found nothing. That doesn’t mean there were no radio signals being transmitted, because Kepler 186f is nearly 500 light-years away, and to be detectable any transmitter on Kepler 186f would have to be ten times the strength of the Arecibo Radio Telescope here on Earth. Or to put it another way, if a civilization like ours exists on Kepler 186f, the SETI search wouldn’t have found it. There might be sentient beings on Kepler 186f right now, uploading the secrets of the universe on to the intergalactic internet; we’ll never know.

  Happily, NASA’s next generation space telescope, the Transiting Exoplanet Survey Satellite (TESS), launches in 2017 and will pick up where Kepler left off, surveying half a million of our nearest stars and hopefully pinpointing thousands of Earthlike planets. No doubt SETI will be quick to target them, but so too will other next-generation space telescopes like the James Webb. Designed to work in the infrared, this fabulous piece of equipment will be perfect for analyzing planetary atmospheres. After all, molecules like oxygen, carbon dioxide, and nitrogen have a distinctive “bar code,” emitting and absorbing light at well-defined frequencies across the spectrum. If we know what we’re looking for, there’s every chance we may be able to detect alien life remotely. Our next-door neighbors may have their lights off and their curtains closed, but telescopes like the James Webb can tell us whether or not they are home. Then Frank Drake will know exactly where to point his telescope.

  THE RESTAURANT AT THE BEGINNING OF THE UNIVERSE

  As we walk to lunch Mazlan tells me how the media came to refer to her as the Alien Ambassador. “I was due to give a talk at a Royal Society confe
rence about extraterrestrial life. I was going to say that if we do receive signals, the United Nations is the best way to coordinate a response.”

  We pass UNOOSA’s space display, and I am temporarily distracted. There’s a beautiful model of the Shenzhou spacecraft, which will be the shuttle craft for the Chinese Space Station, together with its Long March launcher rocket. There is something vaguely familiar about both—the technology is essentially Russian, after all—but it is remarkable to see Chinese characters on the side of spaceships. What a different world it will be in the 2020s, with the International Space Station decommissioned and only Taikonauts in orbit.

  Most of the display items are scale models of satellites; one of UNOOSA’s tasks is to provide a registry of all items launched into space, and then help keep track of anything that ends up in orbit. There are many reasons to love satellites, and one of them has been early warnings of climate change: Their data have given us 90 percent confidence that the planet is warming due to carbon dioxide emissions. That said, what most people love about satellites is the money they make. With GPS, television, and the internet all relying on satellite transmissions, virtually every nation on the planet is trying to get a piece of the action.

  Only that morning I had read an article in the Daily Mail, the gist of which was that while we were pouring aid into Nigeria, they were squandering it on a space race. After feeling suitably furious, it struck me that Nigeria’s space race was probably little to do with planting the Nigerian flag on Mars and more to do with satellites. After all, launching satellites is probably the most sensible way of supplying infrastructure to a developing country that you can possibly imagine. I checked online, and surprise, surprise, that is indeed the purpose of Nigeria’s space program, with telecommunications and Earth observation satellites bringing internet services, weather-mapping, and food security to one of the fastest-growing populations on the planet.

  And, joy of joys, among the display items there’s also a moon rock, found by the astronaut James Irwin of Apollo 15 on the rim of the Spur Crater in the Mare Imbrium, better known as the right eye of the Man in the Moon.11 The mare, or seas, on the Moon are basically enormous impact basins, formed by collisions with asteroids or comets. These basins then flooded with molten lava, which cooled to form huge flat plains of dark basalt, making them ideal landing sites for the early Apollo missions. It’s a sobering thought that the Earth has been similarly disfigured throughout history, though of course thanks to weathering and recycling of its crust via plate tectonics its impact basins have been Botox-ed away.

  “So there’s nothing in it?” I ask. She smiles, and we continue our walk. “A journalist called after the story first broke. She asked me, ‘Are you the alien ambassador?’ I said, ‘I have to deny it. But it sounds pretty cool.’”

  When it comes to messaging aliens, of course, the UN has got form. As we heard in the opening chapter, it’s Secretary-General Kurt Waldheim’s voice that opens Voyager’s Golden Record, and I think I know an audition speech when I hear one. The way things are going, very soon the peoples of Earth are going to need someone to speak on their behalf. Isn’t this the role the UN was born to play? Someone must have thought this through. If the aliens call, surely somewhere among all those reports and resolutions there has to be a protocol? Dr. Othman laughs. “Here at the UN, we simply serve. We don’t create protocols unless we are mandated to by our member states.”

  Suddenly it hits me. There’s only one thing worse than the aliens talking to the UN, and that’s them talking to just about anyone else. After all, we kind of know how this goes. In 1996, when American scientists in Antarctica thought they had found fossilized bacteria in a Mars meteorite, the first the rest of the world knew about it was when President Clinton announced it on TV.12 We need to keep politicians out of it; they’ll just hog the glory. The last thing any of us wants to see is a humanoid alien on the White House lawn, hand in hand with Donald Trump.

  It’s time to put Dr. Othman on the spot. What if an alien ship lands tomorrow? I wince, expecting her to tell me not to be so silly. To my great surprise, she hardly breaks stride.

  “It depends where they land. If they land in Mali, they will be the provenance of Mali.”

  “Really? But what about the UN?”

  “If the government of Mali requested that we became involved, we would get involved.”

  “And if they did make that request?”

  “Then we would need to get it verified. We could help assemble a team of scientists, and assist in obtaining visas, but that could take a couple of months.”

  “But SETI have a protocol, don’t they, for what to do if a ship lands?”

  “There’s a SETI protocol, sure. But it has never been adopted [by the UN].13 There has never even been a debate.”

  WILD MEN OF THE MOUNTAINS

  The Search for Extraterrestrial Intelligence has always struggled to get taken seriously. First of all there’s that acronym, “SETI,” which sounds a bit too close to “yeti” for comfort, and immediately puts the reader in mind of the Bigfoot hoaxes involving blurred camerawork and out-of-work actors blundering about in bad costumes made of 1970s shagpile carpet. And then there’s the Steven Spielberg movie E.T., in which an alien lands on Earth in a spaceship, forevermore linking the word “extraterrestrial” with UFOs. After all, it’s hard to make a serious argument for SETI when your mental image of an alien contact is a wrinkly brown baby-faced midget with a glowing forefinger.

  This mistrust is completely undeserved, if you ask me, and not a little unfair. An admittedly subjective sample of the public, based on taxi drivers, people I’ve sat next to at weddings, and fellow travelers on Network SouthEast rail tells me that people take UFOs very seriously indeed, but are—initially, at least—extremely dismissive of SETI. I can’t understand it. SETI is conducted by professional astronomers on state-of-the-art radio telescopes, while the search for UFOs is conducted by drunk people on their way home from the pub. The science behind UFOs is nonexistent; the science behind SETI is sound. And SETI had its greatest champion in the gifted astronomer Carl Sagan; UFOs have their strongest advocates in the shape of the Church of Scientology. I rest my case.

  As a result of the public’s ambivalence, SETI has been a bit of a stop-start affair. The project began with two independent events. Let’s have a quick refresher on what those were. Firstly, in 1959 two Cornell physicists, Giuseppe Cocconi and Philip Morrison, published a paper in the journal Nature, where they pointed out that the microwave radio band would be a good way for extraterrestrial civilizations to communicate with us, because shorter wavelengths tend to get absorbed by the Earth’s atmosphere and longer ones by the gases in the interstellar medium. They put forward the idea that within this band there was one obvious marker frequency emitted by neutral hydrogen, the most common molecule in the universe.14

  Frank Drake had independently come to the same conclusion, and in 1960 pointed the large telescope at Green Bank at our two closest Sun-like stars, Tau Ceti and Epsilon Eridani, and tuned his receiver to look for signals close to 1,420MHz. As his receiver had a bandwidth of 100Hz, in the technical jargon we might say that he searched one “channel” of 100Hz. He found nothing, and thereby expanded our knowledge of extraterrestrial civilizations: there wasn’t one on either of those two stars. Or, to be more precise, he found no extraterrestrial civilizations that were sending us radio signals close to the hyperfine transition of neutral hydrogen for the 200 hours that he listened in April 1960.

  After Frank Drake’s promising start, the US initiative in SETI failed to attract US government funding and stalled. Drake and others continued to beg, borrow, and steal time on radio telescopes whenever they could, but NASA was slow to take up the cause. In the Soviet Union, however, where the scientific community had not been weaned on War of the Worlds and John Carter of Mars, SETI seemed like less of a joke, and more like a subject for serious scientific study. So after a promising start in the West, with the 1959 paper by C
occoni and Morrison, closely followed by Frank Drake’s vigilante Project Ozma, most of the running on the theoretical side of things was made by the Soviet Union.

  Interestingly, the Soviet take was very different from the American one. Whereas the Americans took it for granted that they would be able to recognize an alien signal, the Soviets weren’t nearly so sure. After all, Ancient Egyptian had only been translated with the help of the Rosetta Stone. Even then it had taken twenty years of academic slog, and Ancient Egyptian was a human language. What hope did we have of recognizing an alien signal even if we found one?

  RUSSIAN DOLLS

  Instead, the Soviets focused on something much more fundamental: energy. Drake’s counterpart in Soviet SETI is the Russian astrophysicist Nikolai Kardashev. In his 1963 paper “Transmission of Information by Extraterrestrial Civilizations,” Kardashev classified civilizations by their energy consumption. It was statistically likely, he argued, that most civilizations in the galaxy are much older than our own. In other words, the chances are we’ve just rocked up at a party that’s been swinging for billions of years.

  The older a technological civilization is, argued Kardashev, the more advanced it would be, and therefore the more energy it would require. He decided to classify them as one of three types, solely on the basis of their energy consumption. A Type I civilization was one which had harnessed all the energy of its home planet. By this measure, our own civilization isn’t quite a Type I, but it’s not far off. A Type II civilization had command of all the energy of its home star; a Type III civilization had harnessed the energy output of its home galaxy.