Life off Earth - Do Aliens Exist?

The next big discovery in science will be the proof that alien life exists - and it could come any day now...

A few weeks ago, I put the finishing touches to one of the most visionary projects I’ve ever been asked to present. The Essential Guide to the 21^st Century is the BBC World Service’s flagship series for the start of the new Millennium. My brief was to investigate where science will take us in the future – and what are the big discoveries coming up.

In the course of a whistlestop tour from the depths of the CERN particle accelerator under the Alps to NASA’s Mars mission control overlooking Los Angeles, scientists predicted some pretty mind-blowing ideas. Around 2020, we’ll be wearing mini-computers as fashion accessories, with mini-robots surging around our bloodstream to scavenge viruses. High overhead, astronauts on the International Space Station will be attended by their own colourful, football-sized personal satellites. And, in case A Brief History of Time wasn’t enough, we’ll have to face the fact that the Universe isn’t made of just three dimensions, but contains six or more tiny extra dimensions all curled up on themselves.

But all the scientists I interviewed were abuzz about the biggest story of all. They agreed that this is the millennium in which we will discover intelligent alien life – and make contact with it.

NASA

The infamous "microbes from Mars". Researchers are still arguing whether these bug like shapes (magnified 100,000 times) are indeed fossilised bacteria.

Until recently, we’ve looked at life in a pretty conservative way. Wildlife films on TV help to reinforce the notion that we – and our fellow-creatures – live within a fairly narrow range of temperatures and environments, and that, deep down, we all bear a strong family resemblance.

But this complacency has all changed. In just the past three or four years, biologists have discovered that life on Earth can exist in the most extreme places, and in the most bizarre forms. Microbes have been found down boreholes two kilometres deep. They live inside rocks scattered across the freezing wastes of Antarctica. White crabs and giant tubeworms inhabit scalding deep-sea vents that never see the rays of the Sun.

These forms of life may look more akin to ‘green slime’ than to our usual idea of life on Earth. But they are still alive. When life gets started, and wherever, it seems determined to hang on … for dear life! So if life got started on our planet – and it did so pretty quickly – then why not on some of our neighbour-worlds in the Solar System?

Mars has long been a favourite with film directors, yielding untold numbers of B-movie aliens. But many scientists are taking things a little more seriously. Knowing that Mars is a smaller, colder version of Earth, they figure it is a good place to start to search. Mars probably

once had a thicker atmosphere that could have supported embryonic life. And it almost certainly had water on its surface in the past – perhaps even oceans. Water is the essential lubricant of all living things: without water, life as we know it cannot exist.

Both NASA and European space scientists have planned a bold program of unmanned Mars exploration that will sniff out life - if it exists – or even the remains of long-extinct life-forms. The American missions are likely to be delayed a couple of years, after the recent losses of NASA’s Climate Orbiter and Polar Lander. This makes me less confident of something I was loudly predicting last summer – that we would see a manned landing on Mars in 2019, exactly 50 years after the Apollo astronauts reached the Moon.

And casting my mind back to last summer brings up vivid thoughts about life in the Universe. My mission then was to cover an international conference on ‘bioastronomy.’ This regular Bioastronomy Conference is held every three years, at some of the most beautiful and inspirational places on Earth – the previous time it was Capri, and next time it will be the Great Barrier Reef. The latest conference was held on the Big Island of Hawaii.

Mars was high on the agenda. Much of the debate concerned possible ‘Martian bugs’. In 1996, strange structures – looking like fossilised wiggly worms - had been discovered inside a meteorite which had been blasted out of the planet and landed in Antarctica. The consensus last summer – alas - was that the "bugs" were too small ever to have been life.

NASA

The cracked, icy surface of Jupiter's water-moon, Europa.

Instead, the scientists were betting on a different ‘best-bet’ for finding life in the Solar System. The smart money now is on Europa, a moon circling the giant planet Jupiter. Europa is dazzling-white, and covered in mysterious cracks. Images from the Galileo spaceprobe show that its surface looks like the pack-ice you see when you fly over the seas around Alaska or Greenland – and that’s just what the bioastronomers believe it is.

The Galileo scientists predict that, underneath the pack-ice, there’s a deep ocean of water warmed by Jupiter’s continual gravitational pummelling. Already, there are plans to send a probe to Europa early this century, equipped with a robotic submarine. Will it find bugs? Or maybe something more exotic like the giant tentacled creatures dreamt up by Arthur C. Clarke in his novel 2010?

The Holy Grail of this new millennium, however, is not to find bugs, but to locate intelligent life. And optimism grows every day. Though we don’t expect to find intelligent life on any of the Sun’s orbiting worlds, there’s a fast-growing list of other places where the aliens might live. Over the past five years, astronomers have been busy finding planets around other stars. The total now stands at 29 – with seven found in the last few weeks!

Keck Observatory

The Keck Telescope on Hawaii searches the sky for planets around other stars.

The technique astronomers use to detect ‘extra-solar’ planets relies on the fact that planets "tug" on their parent stars – like a dog pulling on a leash. The jerk on the star is very small, but by using sensitive instruments, scientists can measure the degree of wobble and infer the masses and orbits of the encircling planets. The most prolific team of planet-hunters is headed by Geoff Marcy of San Francisco State University. Last year, Marcy’s team discovered one star - Upsilon Andromedae – that has three planets in tow, making it the first planetary system to be located beyond our own.

So far, the technique is only sensitive enough to pick up planets as massive as Jupiter or greater. But if there are ‘Jupiters’ in existence, there are almost certainly ‘Earths’ sprinkled amongst them – it is just that our technology cannot yet winkle them out. In the next few years, by using space-based telescopes, we will undoubtedly be detecting worlds out there like our own.

If intelligent life exists on any of these new worlds, how can we make contact? The distances between the stars are too great for us, at our present stage of development, to go in person. (Our fastest spaceprobes, the Voyagers – which travel 20 times faster than a rifle bullet - would take 40,000 years to reach the nearest stars.).

NAIC, Arecibo Observatory

The giant Arecibo Radio Telescope waits for the call from ET...

But for at least part of their evolution, aliens will surely communicate over long distances just as we do: by radio waves. They’re cheap, fast - travelling at 300,000 km per second - and have no worries about covering vast interstellar distances.

For the last 40 years, a small number of astronomers have been listening-in for the elusive signal from ET using huge radio telescopes – like Jodrell Bank, or the vast dish at Arecibo, Puerto Rico. With clever electronic detectors, we can now potentially tune into tens of millions of ‘extraterrestrial radio stations’ simultaneously. The name of the game is SETI – the Search for Extraterrestrial Intelligence.

But the call has never come – despite some heart-stopping moments when interference looked like the real thing. Some astronomers now are considering the possibility that advanced civilisations might instead use laser beams to make contact, and are searching the sky for suspicious flashes of light. But how do you second-guess ET?

And some scientists reckon that astronomers should not be conducting SETI at all. Contact with aliens, they believe, would be downright dangerous for us. Anthropologists have fears that an advanced intelligence – if it had mastered interstellar travel – could come to Earth and wipe out the human race, on the grounds that living creatures are programmed to wipe out rivals. Other researchers believe that the results of downloading the total sum of knowledge from an alien intelligence would blow our puny brains.

But I strongly believe that a dialogue with a more advanced intelligence would help us. We’d learn from their mistakes – and benefit from their advanced knowledge. Of course, none of this would stop us being human, although I think it would change us in ways we cannot yet know.

For those who urge astronomers to call off the search in case we do make contact, I can only say one thing: it’s too late. For the past 70 years, the powerful signals generated by radio and TV transmitters have been leaking away from our planet at the speed of light. They have already reached hundreds of the nearest stars. If ‘they’ are out there, they already know that we are here.