The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

Studies of cometary dust environments in the context of the Comet Interceptor mission

Comets are icy and active bodies that are often thought of as relics of the formation of our Solar System. ESA’s upcoming Comet Interceptor mission aims to be the first mission to a dynamically new comet. This could reveal unprecedented insights, because such an object returns to the vicinity of the Sun for the first time since the formation of the Solar System. In this work, I study the dust environment of comets in the context of the Comet Interceptor mission. I want to answer the following key questions: How do dust particle impacts affect the attitude of spacecraft? How large is the risk that dust particle impacts cause the imaging system to be off-pointing? How can the dust environment of comets be modelled in a time-efficient and flexible manner? To what extent can the dust particle size distribution of a cometary coma be constrained based on its colour? These questions are studied through numerical modelling. I find that, especially at high flyby velocities, dust impacts can significantly affect the attitude of a spacecraft. For Comet Camera (CoCa), the main imaging system onboard Comet Interceptor, it is likely that one or two images will be lost due to the attitude perturbations caused by dust impacts. To create a time-efficient and flexible model of the dust environment, I implement a model that calculates the number densities numerically, but solves the trajectories of the dust particles analytically. By applying this coma model, I find that a spectral ratio of a coma’s brightness (Afρ) correlates with the power-law index of the dust particle size distribution. Specifically, I model the spectral ratio of Afρ(425 nm)/Afρ(900 nm) to provide constraints on the power-law index. Further, the Afρ values of the blue (390-520 nm) and near-infrared (800-980 nm) filters of Comet Camera are ratioed to derive analogous constraints