Orbit Estimation of Lunar Spacecraft Using Earth-Based Optical Sensors
- Paper number
IAC-08.A3.2.INT14
- Author
Mr. Michael Shoemaker, Kyushu University, Japan
- Coauthor
Prof. Darryll Pines, University of Maryland, United States
- Year
2008
- Abstract
Recent interest in lunar exploration has led to an increase in the number of current and planned missions to the Moon, with participation by several countries around the world. With this increase in lunar activity, it is important to consider the feasibility of using Earth-based optical sensors to perform passive orbit estimation of lunar-orbiting spacecraft. Such a capability may: (1) serve as a backup to radio tracking in the case of a vehicle anomaly or loss of contact (2) extend space situational awareness capabilities. While the methods are similar to the problem of optically detecting objects in GEO, the present study focuses on the nuances of applying these methods to the lunar orbital environment. There are many past examples in the literature, dating back to the 1960s, of Earth-based telescopes being used to observe lunar and trans-lunar spacecraft. Often these observations were made with astronomical telescope systems that were not originally intended for satellite tracking. Since the spacecraft tracking angles were measured from star positions using photographic plates or film in that era, the utility for real-time mission operations was minimal. In contrast, the aim of the current study is to explore the feasibility of using existing Earth-based telescopes to perform useful orbit determination, such that a resulting orbit state could be used in actual mission operations. The specular and diffuse reflections of sunlight are predicted for cases which resemble current and planned lunar missions, namely: (1) low-altitude, low-eccentricity polar orbits, typical for scientific and mapping missions (2) high-eccentricity orbits, typical for capture into or departure from the Moon’s sphere of influence. The predicted observations are simulated on a computer and fed into an orbit estimation filter, and Monte Carlo simulations are performed to determine the expected estimation accuracy of the system. The influence of measurement density and orbit geometry on the performance of the estimation process is discussed.
- Abstract document
- Manuscript document
IAC-08.A3.2.INT14.pdf (🔒 authorized access only).
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