ESA GNC Conference Papers Repository
AOCS innovations for Airbus OneSat platform
Supported by ESA and National Space Agencies in France and UK, Airbus Defence and Space is currently developing the OneSat software-defined telecommunications satellite product line. Unlike previous satellites, which are designed for specific and pre-defined missions, OneSat can be fully reconfigured while in orbit and is capable of adjusting its coverage area, capacity and frequency on the fly to meet evolving mission scenarios. By combining the world-class reliability of Airbus Eurostar family and the design-for-manufacturing experience of the Arrow constellation satellites, OneSat represents the new Airbus flagship product for the NextSpace telecommunication market in GEO. The OneSat AOCS architecture strongly relies on Eurostar NEO building blocks, while adopting NewSpace equipment (with automotive-quality EEE components) to meet the right balance between performance and overall ownership costs. Several challenges have, however, been addressed in order to successfully adapt the Eurostar NEO design to meet OneSat specific needs. This paper focuses on the following main topics: OneSat relies on a stacked launch strategy to reduce launch costs. This results in a highly compact platform design, and requires a high number of deployable appendages: 2 Solar Arrays, 2 deployable antenna booms, 2 deployable Electric Propulsion (EP) thruster modules, 2 deployable radiators for heat rejection. Analysis tools have been developed to manage the high number of configurations resulting from the combined variability of the different appendages orientations. And specific appendage command strategies have as well been implemented to manage flexible responses and ensure the overall mission pointing performance. In order to optimize Launch and Early Operations Phase (LEOP), an autonomous transition to a 3-axis Star Tracker based control mode is now introduced, as part of the automatic post-launcher separation spacecraft initialisation sequence. This is an enabler to simplify and accelerate operations. As Eurostar NEO, OneSat implements a combined full electric orbit and wheel momentum control strategy, using two 3-dof robotic arms on which electric thrusters are accommodated. The available impulse for wheel offloading is reduced with respect to typical Eurostar NEO satellites, since the OneSat mass is significantly lower. Wheel offloading requirements are however similar or higher than those of Eurostar NEO. The offloading capacity of the combined Station Keeping / momentum control strategy needed therefore to be improved. This has been achieved by introducing the so-called Twin Manoeuvre concept. Building on the now flight-proven auto-coding process for AOCS flight SW, Airbus delivers to Customers developing their own Station Keeping Ground SW an auto-coded library and corresponding API implementing the algorithms for wheel offloading management. Thanks to the auto-coded libraries, interfaces are greatly simplified thus avoiding lengthy and costly cross-validation phases and allowing Customers to focus on their Flight Dynamics core expertise.