Robotised geostar shines light on Mediterranean seabed

Scientists from Italy, France and Germany have lowered a robotised research station, weighing 1.5 tonnes to one of the deepest parts of the Mediterranean. At 3,500m below the surface, this is almost ten times the height of the Empire State Building.

The unmanned craft, which is subjected to pressure 350 times greater than that on the surface, will remain on the sea bed for eight months while relaying to the surface information on magnetic currents, gravitation, earth tremors, marine currents and water composition.

The selected spot is 15 nautical miles northeast of the island of Ustica and 40 miles north of Sicily. It was the first time that the area had been mapped with precision. The survey by the Italian Institute of Marine Geology was crucial in choosing the exact spot on which to place the station.

Geostar (Geophysical and Oceanographic Station for Abyssal Research) is the name of both the craft and the project. It is financed by e4.6 million from the European Union's Directorate-General 12 and headed by the Italian National Institute of Geophysics, which suggested the project to the EU in 1995. Also involved are the Berlin Technische Universitat, the engineering department of the Berlin Fachhochschule and the Marseilles Laboratory of Oceanography and Bio-geochemistry. The University of Newcastle developed part of the electrochemical sensors for the project early in its life.

Geostar's board of advisers includes scientists from the United States and Japan.

Geostar's "mother ship" is the Urania , an oceanographic survey vessel owned by Italy's National Research Council that is normally used by the Institute of Marine Geology. The many sensors on Geostar will track variations in magnetism and gravity, monitor seismic activity and measure water composition, pollution and sea currents.

The data collected by Geostar is sent by acoustic transmission to a buoy on the surface. From there, it is relayed by radio to a receiver on Ustica and to an Immarsat satellite.

The Geostar project breaks new ground because, unlike the remote operating vehicles that have generally been used for deep-sea research, it is a fixed station on the sea bed with no physical link to the surface. It must be as reliable as a spacecraft because, like an object in orbit, it cannot be serviced once it is in place. And it will provide data for a wide range of research fields.

"Geostar is headed by the Italian National Institute of Geophysics," says Paolo Favili, one of the project coordinators, speaking from the Urania in Civitavecchia harbour as the station was being brought aboard.

"But it is an international enterprise financed by the EU. The docking station, used to deposit and subsequently recover the station, is German. The bottom station was made by Technomare, the engineering division of ENI, the Italian energy giant. The communications system was developed in France."

The greatest technical challenge, says Favili, was the enormous pressure. "The station is designed to stand pressure down to 6,000m. Once lowered to the sea bed, it must stay there for eight months. We cannot go down and tighten this or replace that.

"There is also potential corrosion. And the batteries running the equipment must last eight months, too. To prolong battery life, all the sensors except those monitoring earth tremors will be automatically turned on at specified intervals."

Geostar's website is: www.ingrm.it/GEOSTAR