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This paper describes the lessons learnt during the development and testing of the Modular Architecture for Robust Computing (MARC) demonstration system. It is principally written from a hardware perspective.The MARC system is designed for satellite avionics applications. The network and power architectures are based on established spacecraft redundancy concepts and provide tolerance to single point failures. The MARC architecture is designed to provide a scalable solution that can meet the demanding needs of future missions, the SpaceWire network can be expanded to include new functions and to provide duplicate paths to achieve the level of redundancy needed for a particular mission.An important aspect of the demonstrator hardware is that the key components are space qualifiable parts; permitting the design to be upgraded to a fully space qualified system with minimal changes, in particular the hardware design uses the ESA Atmel AT697F processor and SpaceWire 10X router developments. The ESA SpaceWire RMAP IP Core is also used for all module network interfaces, being implemented within FPGAs.The lessons learnt include the experiences with implementing the RMAP IP Core, VHDL synthesis problems, power consumption issues and the need for detailed internal unit interface specifications. Additional technology developments, such as radiation and fault tolerant Point of Load converters that are required for migration of the design to flight are also identified.Lessons were also learnt regarding parallel Hardware and Software developments to reduce development timescales whilst eliminating diverging design compatibility.

Prototype connectors have been developed by Smiths Connectors (Hypertac) for backplane applications, and testing has been performed by TASUK under ESA contract.The connector is a modular type with different pin inserts for power, signal and high-speed data, making it suitable for SpaceWire applications. This paper describes TASUK's experience designing a test setup and using the backplane connector.

The SpaceWire standards are maintained and issued formally as ECSS documents (e.g. ECSS-E-ST-50-12C) and this means that equipment designed by different agencies is interoperable, which has significant benefits.SpaceWire is mainly used between instrument units, however to facilitate a high level of integration of onboard systems it is proposed that an ECSS SpaceWire Backplane standard should be created and adopted, the backplane offering power, signal and impedance-matched connectivity for high-speed serial links such as SpaceWire and SpaceFibre. The SpaceWire Backplane standard will assist in the aim of creating a common onboard infrastructure to be used across many different mission applications by encouraging design reusability at the sub-unit (PCB plug-in module) level. A key advantage of a SpaceWire Backplane is the scalability of the design.A draft SpaceWire Backplane ECSS standard has been created by TAS-UK as part of an ESA contract. It is based around the Smiths Connectors Nexus modular connector which can be populated with a variety of different contact inserts for power, signal and high-speed data and thus can be tailored to a particular application.