The AOCS subsystem is characterised by: 

• High precision 3-axis control
• The ASTRO instrument is used for precise rate sensing during the fine pointing operational mode
• A high precision gyro is used for quick and efficient transitions during the fine pointing operational mode
• Rugged flight-proven initial acquisition and Safe modes
• Three Sun acquisition sensors plus one gyroscope provide spin-axis stabilisation during the L2 transfer phase of the mission
• One large field of view star sensor plus use of the main instrument sky mappers for the 3-axis controlled operational phase