Attitude estimation of space objects using glint
Abstract
Dynamic states such as shape, attitude, and surface properties are essential information to carry out active debris removal (ADR) and/or to check up operational states of satellites. A cost-effective measure is to inversely estimate dynamic states using light curves, a time history of light intensity reflected in surfaces of orbital objects. One of the difficulties of light curve inversion is that estimation accuracy is dependent on initial attitude angles and initial angular velocities, which comes from less information obtained by the observer compared to plural parameters to be estimated. Previous studies have determined initial states by using the image obtained by radar or adaptive optics. The problem is that previous studies require additional expensive equipment and do not take full advantage of cost-effectiveness of light curve inversion. This paper proposes a state estimation technique that can be completed only with light curves without using high-cost extra instruments by focusing on the rapid change of light intensity, called glint. Although high observability in the vicinity of glint is shown in previous studies, it is difficult to use glint as measurement data and estimation accuracy rather drops immediately after glint because of its high frequency. The proposed method in this paper is based on geometric constraints among the Sun, the observer and surfaces of orbital objects in glint detection. This paper formulates constraint conditions of glint mechanism, and also evaluates the accuracy of state estimation method using glint. Physically meaningless values that did not satisfy the geometric constraints in glint detection are presumed to be excluded from the estimation. Thus, numerical simulations verify that the proposed method can estimate the attitude of a space object with higher accuracy than conventional methods shown in previous studies. It is concluded, therefore, that the attitude estimation method using glint can realize an inexpensive and highly accurate attitude estimation that can be completed only with light curves.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2191M