Star Tracker Cost Reduction for Small Satellites

Abstract

In recent years, the great potential of small satellites has become ever clearer and small satellites are selected to perform increasingly complex missions. With this rise in mission complexity, the requirements on the Attitude Determination and Control System of the satellite increase as well. Of all the attitude determination sensors, the star tracker is by far the most accurate one. The accuracy of this sensor is in the order of arc seconds. The disadvantages of this sensor are that it is expensive, takes a considerable volume, and has a high power consumption. In this paper, we will discuss the star tracker developments that are currently being done at the KU Leuven University. These star tracker developments are part of the development of an ADCS for the SIMBA Mission, which is scheduled to launch within the QB50 campaign. In the first part of this paper we discuss how the novel star tracker algorithms developed at KUL can reduce the cost of the Star Tracker. Both the centroiding algorithm and the tracking algorithm have a significantly reduced computational cost, thanks to analytical solutions of the optimization problem. This can allow to save costs in the electronical hardware and will reduce the strain on the power budget. Furthermore, the star identification algorithm and tracking algorithm are significantly more robust to inaccurate measurements. This allows to yield high accuracy, even with lower cost components. The algorithms will be presented and we will focus on the increased efficiency. In a second part, we discuss the tests that are performed to analyse the performance of the star tracker. For small satellites, testing procedures are often not as standardized as they generally are for satellite missions. As the SIMBA CubeSat is currently being developed as ESA’s first CubeSat through an ESA GSTP project, the test campaign of the KUL star tracker will adhere as strictly as possible to the standards set by ESA. The procedures that are followed will be outlined in this paper and may serve as a guideline for future star tracker test campaigns. This may help to reduce the time and money needed to devise and set up a test campaign for future missions. Since setting up a test campaign is often a serious strain on the manpower and financial budget, this could lead to a serious reduction in cost and lead time. An outlined procedure would also facilitate the comparison between different star trackers on the market and would allow small satellite developers to select the best star tracker for their mission. Both the novel star tracker algorithms and developed testing procedures will allow to make the accurate star tracker more accessible for small satellites. The increased attitude knowledge accuracy that this sensor brings to the satellite platform will allow small satellites to perform even more complex and interesting missions. This will again lead to new opportunities and new developments for this growing group of satellites.status: accepte