Ion thrusters are a new and exciting way of moving spacecraft. Our highly efficient propulsion system reduces the mass of fuel that a spacecraft carries by 90% compared to traditional chemical fuel systems.
A conventional spacecraft burns fuel like a car. The weight of the fuel limits the payload that can be carried and also the length of the mission.
By contrast, ion thrusters propel spacecraft with an inert gas (Xenon) which is ionised by electricity generated from solar panels. The weight of the gas is a fraction of that of conventional chemical fuel. Ion thrusters extend the possibilities of space exploration far beyond our previous limits.
Other benefits of using ion thrusters are they take up less room as the Xenon gas is less bulky (stored as a liquid). This means that the satellite also weighs less and so the costs of launch are cheaper. Another major benefit of this technology is the potential to extend the lifetime of a spacecraft. Satellites will last longer in orbit, with major advantage to satellite owners such as the telecommunications industry who will not need to replace their satellites as often.
Against stiff competition we were selected to design and build the ion thrusters for GOCE, the first of ESA's Earth Explorer Core Missions. The aim of GOCE (Gravity Field and Steady State Ocean Circulation Explorer) is to achieve very accurate measurements of the earth's gravity field, essential in understanding the physical earth.
GOCE is the first of ESA's core explorer missions, part of the living planet programme. Scheduled for launch in 2008, it will be in orbit for two years. Other Earth Observation systems tend to be about 600 - 800 km altitude. GOCE, however, will be a relatively low earth orbit - only 250 km mean altitude - as it needs to take very sensitive measurements, in some cases to within a centimetre accuracy. At this altitude the satellite will experience high levels of drag and require a very efficient attitude control system. |
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