New sub-sea telescope looks down

Artist's impression of the new telescope

by BBC News Online's Damian Carrington

A new £10m space telescope is being installed this week - on the bed of the Mediterranean Sea.
This unorthodox location appears even stranger when you hear that it is looking downwards.

But the astronomers behind the telescope know exactly what they are doing - searching for elusive particles from outer space called neutrinos.

These are as close to nothing as matter gets - no electric charge and very little, if any, mass. But the Universe is believed to be flooded with the speeding particles which can pass through matter as if it was not there.

They have the potential to give information about the darkest parts of the heavens, out of which no other signals emerge.

New view

Dr Thompson and his photodetector

"The Antares telescope will open a new window on the Universe," said Dr Lee Thompson of the University of Sheffield, speaking at the Festival of Science. "When Galileo created his telescope, many surprises resulted."

The sea floor site is required because the water shields the telescope's sensitive detectors from interference. And it looks downwards for a similar reason - to use the whole Earth as a shield from cosmic ray interference.

The neutrinos cannot be detected directly, but when a rare collision with an atomic nucleus occurs a muon particle is produced. This in turn interacts with water or ice to spark a flash of visible light that can be captured by a telescope.

There are a number of experiments already searching for the same phenomena but Dr Thompson said that Antares is the first under the ocean and, more importantly, the first to point south, towards the heart of our galaxy.

No prawns

Antares involves scientists from five European countries and is being installed 35 km off Toulon, France at a depth of 2.4km.

It will consist of at least 13 cables floating vertically up 400m from the sea bed. On each will be 20 football-sized photo-detectors, ready to capture the light flashes. Because the detectors make a grid pattern it is possible to work out the exact direction the neutrino came from.

Dr Thompson also assured his audience that bio-luminescent prawns would not set off the detectors and give a false reading.