Plasma distribution around comet 67P in the last month of the Rosetta mission

Abstract

After accompanying comet 67P/Churyumov–Gerasimenko on its journey around the Sun and observing the evolution of its induced magnetosphere throughout the comet's life-cycle, the Rosetta operations concluded at the end of September 2016 with a controlled impact on the cometary nucleus. At that time, the comet was located more than 3.7 AU from the Sun, but the data still show clear indications of a weak but well developed plasma environment around the nucleus. Rosetta observed this fading cometary magnetosphere along multiple recurring elliptical orbits, which allow us to investigate its properties and spatial structure. We examined the measured electron and neutral densities along these consecutive orbits, from which we were able to determine the structure of the spatial plasma distribution using a simple latitude and longitude dependent model. © 2020 The Authors