ESA GNC Conference Papers Repository

The TET-1 satellite is in orbit since 22nd July 2012. Since 22nd June 2016 it is accompanied by the BIROS satellite to form DLR's scientific 'FireBird' mission. The main task is the monitoring of high temperature events on the Earth such as wildfires. Both satellites base on the TET satellite platform and are using Astrofein's so called 'smart reaction wheels' in their attitude control system (ACS). The concept is based on DLR's first small satellite BIRD (2001-2014). To use smart reaction wheels, especially for the attitude control system was a major design decision from the beginning, since the 'plug & play' capability of smart reaction wheels makes the ACS very flexible, easy adaptable, easy to integrate and reduces the required satellite board computer resources. As a consequence, it supports the reduction of development efforts for the ACS systems. One important feature of such smart devices is the own ('inner') failure detection, isolation and recovery (FDIR) mechanisms. This requires special interfaces of the satellite bus and its subsystems to the devices' FDIR system. The experiences showed that another interface is important too. This is the interface between satellite and ground system. The ground operators had to become familiar with an increased level of autonomy on board as a result of the sophisticated FDIR concept. The actual state of the art devices uses the heritage and experiences made with BIRD; TET-1 and BIROS over more than 15 years in space. The paper will present the underlying system design principles, the requirements, the solutions and the experiences including lessons learned. Furthermore, figures of availability, reliability and performance of the devices in space will be presented. The paper will show both point of views one is the developers side and the other one is the user side.