The mission's primary science goal is to characterise, for the first time, a dynamically-new comet or interstellar object, including its surface composition, shape, and structure, the composition of its gas coma. It will consist of three spacecraft, which will give a unique, multi-point "snapshot" measurement of the comet - solar wind interaction region, complementing single spacecraft observations made at other comets.
The only way to encounter dynamically new comets or interstellar objects is to discover them inbound with enough warning to direct a spacecraft to them. However, the time between their discovery, their passage of perihelion, and their departure from the inner Solar System has until recently been very short, historically months to a year: far too little time to prepare and launch a spacecraft. Therefore, after launch, Comet Interceptor will be "parked"’ at the Sun-Earth Lagrange point L2, and remain there until a target has been discovered.
Comet Interceptor will be launched with ESA's ARIEL spacecraft in 2029. It will be a multi-element spacecraft comprising a primary platform (A), which also acts as the communications hub, and two sub-spacecraft (B1 built by JAXA and B2 built by ESA), allowing multi-point observations around the target. All spacecraft will be solar powered. The spacecraft will remain connected to each other at L2. The mission cruise phase will last months to years. Before the encounter, the spacecraft will separate into its separate elements, probably a few weeks pre-flyby. For very active comets, separation will be earlier, to maximize separation of the spacecraft elements, whilst for low activity targets, separation will occur only a few days before the encounter takes place.
IWF is involved in the Dust-Fields-Plasma package, for which it will build the electronics for the magnetometer on the B2 spacecraft, and in the MANIaC package for which it will build the DPU.
Further information is found here.