ESA GNC Conference Papers Repository

SSTL’s low-cost Altair Star Tracker has flown on 8 spacecraft since 2003. In recent years, increasing demands for improved star tracker performance on Earth Observation missions, such as NigeriaSat-2, led SSTL to procure high-accuracy star trackers from external providers. An internal programme to develop a unit with a higher accuracy than the Altair unit led to a joint development (the Rigel) with Sodern to integrate the SODERN’s Hydra CMOS Camera Head Unit with SSTL’s Data Processing Unit (DPU), based on SSTL’s next generation 750-based OBC. Development costs have been reduced by making use of existing software from the Hydra, Altair and by using a common service and driver layer from the OBC-750. The SODERN’s Hydra Camera Head used on Rigel already passed qualification tests and the first configuration using two Camera Heads will be flight proven in 2012 onboard a LEO mission. Rigel DPU is currently under development for a 2013 launch on a mission for Kazakhstan. An EQM is expected to be undergoing night-sky testing during Q3 of 2011. Development of the Altair low-cost star tracker continues, as there is a clear need for this capability in the Smallsat market. An experiment using the existing Altair optics, with an LCMS-based sensor flew on UK-DMC- 2 in 2009. Some results from this experiment will be presented. The next stage in this development will be a star tracker experiment due to fly on the UK’s TechDemoSat-1 in 2012. This experiment will comprise a 750-based DPU and a new head based on the UK-DMC-2 LCMS sensor experiment, optics derived from a previous UK star tracker programme and the latest generation of COTS MEMS gyros. The schedule for delivery of this experiment is extremely tight, with hardware required by 2011 Q3. It will be shown how SSTL’s development approach makes maximum use of heritage developments allowing such challenging timescales to be achieved.