Spacecraft Onboard Data Handling


Spacecraft have complex electronic data handling systems to collect data from sensors, process and store this information, to send it to a ground station and to receive commands from the ground. The Space Technology Centre is developing technology for spacecraft sensors and onboard communications networks. It was at the forefront of work on the SpaceWire standard, having written the SpaceWire standard document with input from spacecraft engineers across Europe, and is now researching higher-layer protocols for SpaceWire and faster technologies like SpaceFibre. Work on sensor technology includes wideband spectrometers and vision systems for various applications.


SpaceWire has emerged as one of the main data-handling networks for spacecraft since the SpaceWire standard was published in January 2003. It is now being used on many ESA, NASA and JAXA spacecraft and by other space agencies, research organisations and space industry across the world. SpaceWire is designed to connect together high data-rate sensors, processing units, memory sub-systems and the down link telemetry sub-system. It provides high-speed (2 Mbits/s to 200 Mbits/s), bi-directional, full-duplex, data links which connect together the SpaceWire enabled equipment. Networks can be built to suit particular applications using point-to-point data links and routing switches. Application information is sent along a SpaceWire link in discrete packets. Control and time information can also be sent along SpaceWire links. One of the main advantages of SpaceWire is its low complexity (low gate count) and the fact that it can be implemented easily in both ASICs and FPGAs. SpaceWire is supported by several radiation tolerant ASICs designed by or for ESA, NASA and JAXA, and extensive test and development equipment is available.


SpaceFibre is a proposed high-speed serial data-link standard intended for use in data-handling networks for high data-rate payloads and in high-reliability avionics systems. SpaceFibre is able to operate over fibre optic and copper cable and support data rates of 2.5 Gbit/s and higher. It aims to complement the capabilities of the widely used SpaceWire onboard networking standard: improving the data rate by a factor of 10, reducing the cable mass by a factor of four and providing galvanic isolation. Key features of SpaceWire will be retained: simplicity, low implementation cost (gate count), time-code distribution, and redundancy support.