Starlight Angle
Author: Tianjiang Shuo
Website: https://cislunarspace.cn
Definition
The angle measured from the spacecraft between the line-of-sight to a near celestial body (e.g., Earth or Sun) and that to a far celestial body (navigation star), serving as the primary observable for celestial navigation. The starlight angle encodes spacecraft position information into a geometric angle: changes in position cause changes in angle, allowing position estimation through filtering algorithms. Unlike celestial navigation in two-body problems, spacecraft near libration points can select two primary bodies (Sun and Earth), providing richer observational information. The paper finds that using Earth as the primary body yields navigation accuracy one order of magnitude better than using the Sun, because the spacecraft is only about 1.5 million km from Earth, producing a much larger angular span.
Application Value
This concept provides fundamental support in cislunar space research and mission design. In practical applications, the appropriate analysis method should be selected based on specific mission scenarios and constraints.
Related Concepts
- Hovering Control
- Prior constraint
- Absolute Navigation
References
- 赵书阁 等 - 2013 - 日地系统L2点Halo轨道自主天文导航及精度分析