French instruments COMPLIMENT and LEES, developed in Orléans and Toulouse, have been delivered to the European Space Agency for the Comet Interceptor mission. The Lagrange laboratory at the Observatoire de la Côte d'Azur in Nice is co-scientific lead for the COMPLIMENT instrument. Concurrently, the Nice team is developing digital comets on supercomputers to anticipate observations for the probe, whose target is not yet known.
The COMPLIMENT instrument will continuously measure the plasma surrounding the comet during the flyby. It will analyze the quantity and temperature of electrons and ions, the satellite's electric charge, the electric field, waves, solar ultraviolet radiation, and impacts from the finest cometary dust particles, remnants of the solar system's formation.
The Comet Interceptor mission, launching in late 2028 or early 2029, will wait at the L2 Lagrange point for a dynamically new comet from the outer Solar System to appear. These near-pristine comets are only detected months before their solar passage, too late to build a spacecraft. The simulation work in Nice is therefore crucial for interpreting data acquired during a unique flyby.
The Menura code, developed at the Lagrange laboratory, simulates the interaction between solar wind and the interplanetary medium. It revealed that solar wind dynamics erode the cometary tail in bursts, overestimating the predicted matter density by half. The virtual comet thus becomes an essential preparatory laboratory.
Nice's expertise extends to the Plasma-PEPSC 2 project, a European supercomputing plasma simulation center of excellence coordinated by the KTH Royal Institute of Technology in Stockholm. The Lagrange laboratory is the sole French partner, contributing expertise on two numerical codes and bridging high-performance computing with European exploration missions like BepiColombo and JUICE.
The mechanisms studied around comets are similar to those observed around Mars and Venus, and turbulence also affects the shock formation upstream of Earth and Mercury. Work will continue in Nice to prepare the mission, even after its launch.
