France: Astrium is preparing a new technology mission for the maintenance and disposal of satellites. The DLR Space Administration announced that Astrium Friedrichshafen will be the prime contractor for the definition phase of the DEOS (German orbital servicing mission) project. The order is worth a total of around EUR 13 million. The definition phase is the last, decisive step before construction begins on the space vehicles themselves.
The DEOS project will for the first time demonstrate technologies for the controlled in-orbit disposal of a defective satellite. In addition, DEOS will practice how to complete maintenance tasks – refuelling in particular – that extend the service life of satellites. DEOS consists of two satellites, a ‘client’ and a ‘servicer’. The client acts as the satellite requiring maintenance or disposal. The servicer carries out the necessary work on the client. The two satellites will be launched together and brought into orbit at a height of 550 kilometres. According to current planning, DEOS will be ready for launch in 2018.
Testing of disposal and maintenance on a client satellite specially launched for this purpose, as opposed to tests on old existing satellites, means that a wide variety of defects can be simulated. This enables DEOS to demonstrate a complete range of relevant tasks, right up to capturing a satellite that is spinning out of control. Experiments will be performed in an increasing order of difficulty.
The maintenance or disposal of a satellite requires mastering a large number of individual tasks: the servicer has to approach the client without a tracking signal or similar help from the client. The servicer has to remain at a distance of around one metre from the client for an extended period (>1 orbit) while adjusting its position to avoid collision with the client. Throughout the orbit, the approach navigation and attitude control must function reliably even when the satellite is in the full glare of the sun or in eclipse.
Before maintenance work can begin, the servicer must establish a firm grip on the client satellite. It must be capable of establishing electrical connections with the client and connecting a vacuum-tight fuel valve. In order to perform such a wide range of tasks, DEOS will be equipped with a robot arm that can move through seven degrees of freedom.
To a large extent, DEOS is reliant on technologies that have not yet been tested for space operations. In the definition phase, therefore, initial prototypes of the key technologies will be developed, so that subsequent realisation of the project can progress swiftly. This development work will be carried out by Astrium itself and by specialist companies and research institutions subcontracted by Astrium.