Orbit determination and accuracy analysis for comet 311P based on space-based and ground-based optical data

Objectives: China has formulated plans to undertake a proximity exploration of comet 311P/PANSTARRS (previously known as P/2013 P5) around 2034. However, the successful execution of this mission is contingent upon obtaining an accurate determination of the orbit of comet 311P. Methods: In this paper, the SPOT (Small Body Precise Orbit Determination Toolkit) developed by the Planetary Radio Science Team of Wuhan University is used to perform a study of the precise orbit determination for comet 311P in the context of China’s small body exploration mission. We used the optical observations of ground-based and space-based telescopes released from 17 October 2005 to 18 January 2021. Results: The position and velocity uncertainties of comet 311P obtained by SPOT are about 130 km and 5.034 × 10^-3 m/s respectively, which are in close agreement with the position and velocity uncertainties (135.8 km and 5.270 × 10^-3 m/s) calculated by the well-known OrbFit. Conclusions: This experimental outcome not only validated the dependability of the optical data-based orbit determination module of the SPOT software, but also highlighted that the current positional uncertainty of comet 311P’s orbit is on the order of hundreds of meters. Furthermore, this study investigates the influence of the mechanical model utilized in the orbit determination process on the calculation results. The findings indicate that the gravitational field of the 16 large main belt asteroids, as well as the perturbations caused by general relativity and solar light pressure, can be neglected in the current orbit determination process of 311P. Additionally, the paper evaluates the potential impact of ground-based optical observations conducted before the mission on the orbit determination of Comet 311P. Conclusions: The results suggest that such observations have the potential to reduce the orbital uncertainty of the comet, but the uncertainty in the position of the orbit still remains significant, with values reaching tens of kilometers.