ESA F-Class Comet Interceptor: Trajectory design to intercept a yet-to-be-discovered comet

• Published in: Acta astronautica 2021-11, Vol.188 (November), p.265-277
• Main Authors: Sánchez, Joan Pau, Morante, David, Hermosin, Pablo, Ranuschio, Daniel, Estalella, Alvaro, Viera, Dayana, Centuori, Simone, Jones, Geraint, Snodgrass, Colin, Levasseur-Regourd, Anny Chantal, Tubiana, Cecilia
• Format: Article
• Language: English
• Subjects: Comet-I; Earth orbits; Hybrid propulsion systems; Hybrid propulsion trajectories; Lagrangian equilibrium points; Lunar swing-by; Mission planning; Monte Carlo simulation; Sciences of the Universe; Spacecraft; Spacecraft design; Third body effects; Trajectory design
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2021.07.014

Comet Interceptor (Comet-I) was selected in June 2019 as the first ESA F-Class mission. In 2029+, Comet-I will hitch a ride to a Sun-Earth L2 quasi-halo orbit, as a co-passenger of ESA's M4 ARIEL mission. It will then remain idle at the L2 point until the right departure conditions are met to intercept a yet-to-be-discovered long period comet (or interstellar body). The fact that Comet-I target is thus unidentified becomes a key aspect of the trajectory and mission design. The paper first analyses the long period comet population and concludes that 2 to 3 feasible targets a year should be expected. Yet, Comet-I will only be able to access some of these, depending mostly on the angular distance between the Earth and the closest nodal point to the Earth's orbit radius. A preliminary analysis of the transfer trajectories has been performed to assess the trade-off between the accessible region and the transfer time for a given spacecraft design, including a fully chemical, a fully electric and a hybrid propulsion system. The different Earth escape options also play a paramount role to enhance Comet-I capability to reach possible long period comet targets. Particularly, Earth-leading intercept configurations have the potential to benefit the most from lunar swing-by departures. Finally, a preliminary Monte Carlo analysis shows that Comet-I has a 95–99% likelihood of successfully visit a pristine newly-discovered long period comet in less than 6 years of mission timespan. •Comet-I mission aims to explore a Long Period Comet; ideally, dynamically new.•Such a target will remain unidentified, possibly, even after launch.•The paper analyses the orbital space that will be accessible for Comet-I S/C.•Chemical, electric and hybrid propulsion systems are modelled in patched-conic.•A Monte Carlo analysis shows a 95–99% of completing the mission within 6 years.