formation flying system validation and verification for xeus
- Paper number
IAC-08.D1.3.3
- Author
Dr. Alex Wishart, Astrium UK, United Kingdom
- Coauthor
Mrs. Marie-Claire Perkinson, EADS Astrium Ltd., United Kingdom
- Coauthor
Dr. Simon Grocott, EADS Astrium Ltd., United Kingdom
- Coauthor
Dr. Andrew Davies, Astrium UK, United Kingdom
- Year
2008
- Abstract
The XEUS X-ray astronomy mission is proposed to comprise a mirror spacecraft and a detector spacecraft flying in a halo orbit about the L2 point. The two spacecraft will manoeuvre cooperatively in a precisely controlled formation in order to achieve the mission science objectives. XEUS is an example of how the technique of Formation Flying enables missions which are more ambitious in scope than could be envisaged with a single spacecraft. Formation Flying techniques have been extensively studied and the requisite new sensor, actuator and GNC technologies are currently under development in Europe. This paper focuses on another aspect of Formation Flying mission design, namely the ground testbeds which will be used throughout the spacecraft development programme to validate and verify the system. System verification is a major cost and schedule driver for such a complex and novel mission. The paper describes developments at Astrium Limited on the definition, specification and design of the Formation Flying ground testbed infrastructure. The target mission is XEUS, although the testbed is planned to be generic and could be applied to other science or Earth Observation Formation Flying missions. The XEUS system architecture is presented, with the emphasis on the significant design and verification issues which have been identified relating to the Formation Flying AOCS. The paper highlights the important Formation Flying mission objectives and system design drivers, showing where these differ from a classical single spacecraft mission. The functional and performance requirements of the Formation Flying manoeuvres are analysed, and the mission and AOCS architectures developed to meet these requirements are described in some detail. Specific issues arising for Formation Flying including the science payload, sensors and actuators, on-board software and performance verification are examined. Having established a hierarchy of sub-systems involving the new sensors, actuators, and command, control and guidance functions, the paper then goes on to describe how these will be validated and verified in the ground testbeds. This will involve new developments to the classical test benches, software verification and real-time testing processes already in use. In particular the new testbed infrastructure required will include 2-D hardware demonstrations with hardware in the loop. These 2-D demonstrations can be shown to be sufficient for validating 3-D software models of the spacecraft and their environment. Comparison is made with current validation and verification technology being used on single spacecraft missions of similar complexity.
- Abstract document
- Manuscript document
(absent)