Encendido el motor de propulsión iónica de GOCE   The need for GOCE to fly in a low orbit means it has to compensate for the atmospheric drag it experiences at this exceptionally low altitude. The animation shows a close-up of the ion-propulsion assembly, which keeps the satellite in a smooth trajectory – free from all effects except those of gravity itself. Two winglets provide additional aerodynamic stability.   View in ESOC's Main Control Room   GOCE is a sleek five metre-long satellite about one metre in diameter. It consists of a central octagonal tube with seven internal 'floors' that support the equipment and electronic units. The satellite is built largely of carbon-fibre reinforced plastic sandwich panels to guarantee stable conditions and minimise mass. Forming the heart of the satellite, the gradiometer is mounted close to the satellite’s centre of mass. The gradiometer structure is based on ultra-stable carbon-carbon technology. GOCE is the first mission to employ the concept of gradiometry in space. Release date: 13 abril 2009