In-Orbit Attitude Determination of the UVSQ-SAT CubeSat Using TRIAD and MEKF Methods.

Adrien Finance,Philippe Keckhut,Antoine Mangin,Alain Sarkissian,Mustapha Meftah,Christophe Dufour,Thomas Boutéraon

doi:10.3390/s21217361

Abstract

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a CubeSat dedicated to the observation of the Earth and the Sun. This satellite has been in orbit since January 2021. It measures the Earth’s outgoing shortwave and longwave radiations. The satellite does not have an active pointing system. To improve the accuracy of the Earth’s radiative measurements and to resolve spatio-temporal fluctuations as much as possible, it is necessary to have a good knowledge of the attitude of the UVSQ-SAT CubeSat. The attitude determination of small satellites remains a challenge, and UVSQ-SAT represents a real and unique example to date for testing and validating different methods to improve the in-orbit attitude determination of a CubeSat. This paper presents the flight results of the UVSQ-SAT’s attitude determination. The Tri-Axial Attitude Determination (TRIAD) method was used, which represents one of the simplest solutions to the spacecraft attitude determination problem. Another method based on the Multiplicative Extended Kalman Filter (MEKF) was used to improve the results obtained with the TRIAD method. In sunlight, the CubeSat attitude is determined at an accuracy better than 3 (at one ) for both methods. During eclipses, the accuracy of the TRIAD method is 14, while it reaches 10 (at one ) for the recursive MEKF method. Many future satellites could benefit from these studies in order to validate methods and configurations before launch.

Highlights

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a scientific and technological demonstrator dedicated to the observation of essential climate variables [1]
The nadir direction in the body frame is obtained from the transformation of the nadir vector in the orbital frame
The average of the standard deviations of the Sun LOS gradients is equal to 5.17 × 10−3 s−1 for the Tri-Axial Attitude Determination (TRIAD) method compared to 4.1 × 10−3 s−1 for the Multiplicative Extended Kalman Filter (MEKF) method (UVSQ-SAT data on the 2 and 3 February 2021)

Summary

Introduction

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a scientific and technological demonstrator dedicated to the observation of essential climate variables [1]. UVSQ-SAT was launched into a Sun-synchronous orbit by the LATMOS with the Falcon 9 rocket on 24 January 2021. The methods used by [1] to obtain these results (maps of the solar radiation reflected by the Earth and of the outgoing longwave radiation at the top of the atmosphere) do not take into account the attitude of the UVSQ-SAT CubeSat. To improve the accuracy of the results, it is highly recommended to have an excellent knowledge of the attitude of the UVSQ-SAT CubeSat. To improve the accuracy of the results, it is highly recommended to have an excellent knowledge of the attitude of the UVSQ-SAT CubeSat This would allow researchers to obtain the Earth’s incident flux on each UVSQ-SAT face, given that the CubeSat has Earth radiative sensors and photodiodes on all its faces [1]

Results

Discussion

Conclusion