Life off Earth - Do Aliens Exist?

NASA The tiny Sojourner rover on the Martian surface.

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.

Alien oceans

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?