Presentation Information
[PPS03-P14]Development of an Estimation Method for Cometary Dust Mass Distribution Using Spacecraft Attitude Data for the Comet Interceptor Mission
*Noriwa Watanabe1, Satoshi Kasahara1, Takahiro Sasaki2, Naoya Ozaki3 (1.The University of Tokyo, 2.Research and Development Directorate, Japan Aerospace Exploration Agency (JAXA), 3.Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA))
Keywords:
Comet,Comet Interceptor,Cometary Dust,Attitude Control,Mass Estimation
Comet Interceptor is the world's first exploration mission targeting a long-period comet, conducted jointly by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The mission plans to perform flyby observations through the coordination of one main spacecraft and two smaller probes, with a launch targeted for 2029. Elucidating the dust environment in the vicinity of the comet is crucial for understanding the mechanisms of cometary activity and evolution, the material composition of the comet nucleus, and ultimately, the planetary formation process. Furthermore, this information is indispensable for evaluating dust impact risks during the high-speed flyby and ensuring mission safety. Due to resource constraints, Probe B1 of this mission is not equipped with a dedicated dust instrument. However, in the case of the Halley’s Comet explorer "Suisei," which similarly lacked a dust counter, it was demonstrated that the lower limit of the impacting dust mass could be estimated by analyzing attitude changes and spin rate variations caused by dust impacts. Unlike "Suisei," Probe B1 has a nearly cuboid shape and utilizes three-axis attitude control, yet the basic principle of capturing changes in angular momentum due to dust impacts remains the same. While referencing the approaches of such prior studies, it is necessary to construct an estimation model tailored to B1's specific hull shape and control laws. Therefore, this study aims to develop and examine a method for estimating the mass and distribution of dust using data from the three-axis attitude control system, focusing on the attitude and angular velocity changes induced by dust impacts. When the spacecraft passes through the dust coma at high speed, numerous dust particles impact the hull; these impacts exert a disturbance torque on the spacecraft, resulting in attitude changes. The spacecraft's attitude control system drives reaction wheels to counteract these changes and maintain the desired attitude. In this study, aiming to estimate the mass of impacting dust from attitude change data that includes this reaction wheel response, we conducted dust impact simulations based on the Comet Interceptor spacecraft model and assumed flyby conditions. After assuming dust size and spatial distributions, we generated impact events on the spacecraft using Monte Carlo simulations and reproduced the responding behavior of the attitude control system. Using the obtained time-series data, we attempted to estimate the mass of individual impacting dust particles. Simulation results indicated that impacts by relatively large dust particles are detectable as rapid fluctuations in the attitude data. We also evaluated the influence of uncertainty regarding the dust impact location on the accuracy of the mass estimation. This presentation will discuss the overview of the developed estimation algorithm, as well as the estimation accuracy and detection limits of this method. If established, this method would enable the estimation of dust mass distribution around comets by utilizing spacecraft attitude data even for probes without dedicated dust counters, suggesting broad potential applications for future planetary exploration missions.