The discovery of vast stretches of water between the stars has raised new questions about the origins of life on Earth, writes Tim Radford
European scientists, using an ultra-cold orbiting telescope, have discovered unimaginable volumes of water in the space between the stars. The discovery raises new questions about life elsewhere in the universe -and provides new answers about why life was possible on Earth.
The scientists were astounded to find water vapour in the freezing atmospheres of Jupiter, Uranus, Neptune and Saturn.
They also recently revealed they have detected water in the atmosphere of Saturn’s mysterious moon, Titan – which is to be visited by a joint United States-European probe in 2004. They have even identified a cloud of water, less than a light year across, in the constellation Orion.
Hydrogen is the raw material of the universe. Oxygen is made in huge quantities by the stars. So water should be no surprise.
There have been fleeting glimpses of water vapour on the sun’s surface and, in March, the Americans confirmed the presence of water on the moon. But the discovery of vast oceans of water vapour – the mass of which in the Milky Way galaxy alone would equal that of tens of thousands of suns – by the European Space Agency’s infra-red space observatory (ISO) astonished astronomers.
Using instruments called spectroscopes, scientists have identified an astonishing range of organic molecules in space, including hydrogen cyanide, alcohol and formaldehyde.
But water is the first requirement for life. The R5-billion ISO experiment confirms once again that there could be life on planets in other solar systems. The next step will be to look for tell-tale signs of life itself: concentrations of oxygen or ozone in distant planetary atmospheres.
The ISO discovery also confirms a growing belief that water on Earth may have been delivered by comets, icy scraps of dust left over from the birth of stars.
The experiment opens a new window on the universe. More than 1 000 astronomers from Europe, Japan and the US have used the telescope, launched in 1995, for more than 26 000 observations. The data returned will keep researchers busy for years.
“All the missions we undertake in the European Space Agency have to be unique,” said Roger Bonnet, head of science at the space agency. “In principle, the Americans have done everything, so what remains to be done is impossible. All our missions are mission impossible, but ISO is more impossible than any other.”
ISO should have survived for only 18 months, but is still operating after 29. The telescope posed a huge technical challenge: to detect infra-red rays, it had to be cooler than any object it looked at – and the average temperature of deep space is -270C. So ISO had to be cooled with liquid helium, which kept the instrument’s temperature just above absolute zero (-273C).
The satellite has peered into clouds of space dust to watch the formation of solar systems, and deep into the heart of ultra-luminous galaxies.
It has also witnessed two galaxies colliding and, in one of them, the signature of a black hole sucking a blaze of stardust into itself.
Besides mapping the edge of the known universe, it has also seen a star being born inside the Horsehead nebula.