Swarming into space

2 min read

UK engineers are to develop key systems for a major European space project that aims to place satellites in formation above the Earth.

European group EADS Astrium has been awarded a contract from ESA to develop and build the three satellites needed for the space agency’s Swarm mission, which is scheduled for launch in 2010.

Swarm will consist of the three satellites flying in formation to provide detailed data on the Earth’s magnetic field, a project that could substantially aid the search for valuable new reserves of natural resources. EADS Astrium is to set up a joint Anglo-German team for Swarm.

The group’s UK base at Stevenage, Hertfordshire, will be responsible for the propulsion system, structure and other mechanical elements of the Swarm satellites.

The UK arm of the company will also be responsible for the crucial RF communication link with the ground base.

Two of the three satellites will fly side by side at an altitude of 450km, while the third will fly above them at 530km. The satellites will be equipped with an array of scientific instruments that will provide ESA’s astronomers with high-precision and high-resolution measurements of the strength, direction and variations of the Earth’s magnetic field.

The data will be complemented by precise accelerometer and electric field measurements. This will offer an insight into the composition and processes of the Earth’s interior and allow more detailed analysis of the Sun’s influence on the planet.

According to Brian Robinson, project leader for EADS Astrium UK, the biggest challenge in developing the satellites is ensuring that they do not damage each other in orbit. ‘Because the satellites are pretty much autonomous and at the same altitude it is a real problem working out how to launch the two satellites into the same orbit without them colliding,’ he said.

One option is to send the second 450km satellite up on a separate rocket which would add significantly to the cost of the mission, already standing at an estimated N86m (£59m).

An alternative would be to send one satellite into an intermediate orbit first before using reignition of a stage of the rocket to move it into the high orbit.

One of the key areas in which the UK site will be involved is the development of the deployable boom, which carries many of the scientific instruments needed for Earth observation. The 4.5m-long boom will keep the sensitive scientific devices at a safe distance from the satellites themselves.

The three satellites, due for launch in 2010, will collect detailed data on the Earth’s magnetic field.

‘These magnetometers are so sensitive that it is crucial that they are kept magnetically clean,’ said Robinson. ‘We have to develop the boom so it keeps them far enough away from interference from the satellites’ own electronics.’

The satellites will remain in a polar orbit, where they will have only one opportunity each day to ‘data dump’ all the previous day’s recordings to a base station on the ground, said Robinson.

An on-board computer stores the satellites’ position — to be beamed back in the once-a-day transmission — through a ‘startracker’ instrument which uses the stars to give information on the craft’s orbit. According to Robinson, other UK companies will also have a chance to be involved in the Swarm project.

These are likely to include space technology specialists such as Surrey Satellites and Qinetiq who will be given the chance to bid for the development of some aspects of the satellite, including its on-board computer.