Abstract
The Orsted Star Imager comprises the functionality of an advanced stellar compass (ASC), i.e. it is able to autonomously solve 'the lost in space' attitude problem, as well as determine the attitude with high precision in the matter of seconds. The autonomy makes for a high capability for error rejection and fault recovery, as well as 'graceful degradation' at radiation, false object or thermal loads. The instrument was developed from Concept to flight model within 3 years. The instrument surpasses the initial specifications for all parameters, for precision, computational speed and fault detection and recovery by orders of magnitude. This was accomplished by the use of advanced high level integrated chips in the design, along with a design philosophy of maximum autonomy at all levels. The instrument tracks all stars in the field of view, which enables a variety of applications not normally associated with conventional star trackers. Initially, this paper gives a general description of the ASC, including its primary specifications and performance levels. Some of the more promising of the advanced applications are then discussed, along with test-results and methodologies. The diversity of the advanced applications are vast, as depicted by the topics addressed, namely: (1) Detection and tracking of distant non-stellar objects (e.g. meteors). (2) Delta-V correction, for encounter phases. (3) Tracking of selected objects (e.g. guidance for other instruments). (4) Mass estimation via pellet ejection. (5) Complex object surface tracking (e.g. space docking, planetary terrain tracking). All the above topics have been realized in the past, either by open loop, or by man-in-the-loop systems. By implementing these methods or functions in the onboard autonomy, a superior system performance could be achieved by means of the minimal loop delay. But also reduced operations cost should be expected.
