SpaceWire: What, Why, Where
- Paper number
IAC-06-D1.P.1.08
- Author
Mr. Paul Walker, 4Links Limited, United Kingdom
- Coauthor
Dr. Barry Cook, 4Links Limited, United Kingdom
- Year
2006
- Abstract
The purpose of this paper is to show how SpaceWire is having a major effect on current and future space system architectures and how it can increase performance, efficiency, reliability, and flexibility of spacecraft subsystems and systems. SpaceWire has been mentioned in previous papers at IAC, but always in the context of a particular mission or application. By contrast, this paper will present the concepts which make SpaceWire so influential on future spacecraft design, and will survey the missions that are so using it. SpaceWire can be seen as an extremely simple “data bus” that connects between the different instruments, processors, mass memories and RF communications etc. on a spacecraft. At its simplest level SpaceWire is a high-speed replacement for RS422, increasing performance up to several hundred Mbits/s on each link. A minimalist packet protocol makes it possible to build SpaceWire networks with (hardware) routing switches so that virtual point-to-point connections can be made between any two nodes in the network. There are no constraints on topology and links can be multiplexed or aggregated, so that any amount of bandwidth can be provided by adding more SpaceWire links, and the appropriate redundancy can be provided to give the reliability required. Higher-level protocols can be implemented with minimal overheads. The resulting performance, reliability and efficiency greatly extend the applicability of SpaceWire as an on-board data bus, enabling modularity and much greater flexibility in the partitioning of functions between different parts of the spacecraft. A precursor of SpaceWire was used in the 1990s on the SOHO mission and on a number of satellites made by Surrey Satellite Technology Limited (SSTL). These satellites used the connections in a redundant network, with the routing-switch function performed in software. An early version of SpaceWire, standardized as IEEE 1355, is on Rosetta, Mars Express, and Venus Express, in Europe, and SDO in the US where the links are used as point-to-point links without routing switches. GOES-R, GPS-III and LRO are all planning to use SpaceWire for at least part of the mission. James Webb Space Telescope (JWST) is using a large number of SpaceWire connections, with simple routing switches. Other missions include Bepi-Columbo to visit Mercury and the European Drawer Rack for the ISS. A pointer to future use of SpaceWire’s modularity is for “Responsive Space” architectures, reducing satellite lead times and offering easier system configuration for the Shuttle or CEV.
- Abstract document
- Manuscript document
IAC-06-D1.P.1.08.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.