Low-energy electron spectrometer to study the far environment of a dynamically new comet as a part of the Comet Interceptor payload

Comet Interceptor is the ESA F1 space mission aiming to explore a comet very likely entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star, scheduled for launch in 2029 together with the ESA L-class Ariel spacecraft. Following the mission adoption in June 2022, the spacecraft and scientific payload development have advanced to the Phase C. In our contribution we present the status of development of the Low-energy electron spectrometer (LEES) that is a part of the Dust-Fields-Plasma multi-instrument suite deployed at the main spacecraft A (DFP-A).

The DFP-A/LEES sensor will determine the thermal and suprathermal electron densities, temperatures, and the velocity distribution functions of the local plasma environment of both the solar wind and coma. It will also measure the local properties of negatively charged ions and dust, and detect photoelectrons resulting from neutral-plasma interactions in order to infer the magnetic connectivity between the cometary environment and the spacecraft. The LEES measurements are needed to understand the ionization sources of the cometary neutral gas as well as to infer the plasma boundaries of the induced magnetosphere of the comet. The electron spectrometer is a further miniaturized version of the top-hat analyser inherited from the Stereo, Maven and BepiColombo missions. We present the overall design, simulation of the spacecraft electromagnetic and particle environment influence to the LEES measurements and the intermediate results of testing of the LEES components to survive a potential harsh dust environment during the comet flyby.