The ESA-JAXA BepiColombo mission: status and first results

Abstract

BepiColombo was launched on 20 October 2018 from the European spaceport Kourou in French Guyana and is now on route to Mercury to unveil Mercury’s secrets. BepiColombo a joint project between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) consists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). It will perform measurements to increase our knowledge on the fundamental questions about Mercury’s evolution, composition, interior, magnetosphere, and exosphere.  During its 7-year long journey to the innermost terrestrial planet Mio and MPO are connected to each on-top of the Mercury Transfer Module (MTM). The MTM contains a solar electric propulsion engine and will bring the two spacecraft to Mercury. In late 2025, this ‘stack’ configuration is abandoned, the MTM will be jettisoned and the individual elements spacecraft are brought in to their final Mercury orbit: 480x1500km for MPO, and 590x11640km for Mio.  On its way BepiColombo with its state of the art and very comprehensive payload has several opportunities for scientific observations - during the cruise into the inner solar system and during its nine planetary flybys (one at Earth, two at Venus and six at Mercury). However, since the spacecraft is in a stacked configuration not all of the instruments can be operated during the cruise phase.Some of the instruments have been already operated regularly or partially during the flybys in their “scientific” observation mode: e.g. the magnetometer (MPO-MAG), the accelerometer (ISA), the environmental sensor (BERM), the gamma-ray and neutron spectrometer (MGNS), the solar intensity x-ray and particle spectrometer (SIXS), the radio science experiment (MORE), using the X-band and the Ka-band, the thermal infrared spectrometer (MERTIS), the UV spectrometer (PHEBUS) and some sensors of the SERENA suite. Also, instruments or some parts of the instruments of the Japanese Mio spacecraft like the dust monitor (MDM), the plasma wave instrument (PWI), the particle and plasma experiments of MPPE and the magnetometer (MGF) were already successfully operated in their science modes. BepiColombo also took regular “selfie” images with their three monitoring cameras on the MTM. These cameras were also able to take a sequence of outreach images during the flybys at Earth and Venus in 2020. Other instruments such as cameras and NIR spectrometer (SIMBIO-SYS), the laser altimeter (BELA), the x-ray spectrometer (MIXS), and parts of the electron, neutron, and iron sensors of SERENA on MPO and MSASI and some dedicated sensors of PWI and MPPE are operational, but can only be used in their scientific modes after the Mercury in-orbit commissioning in early 2026 because their field of view is blocked by the underlying Transfer Module.Despite the reduced instrument availability, scientific and engineering operations has been scheduled during the cruise phase, especially during the swing-bys. A status of the mission and instruments and a summary of first results from measurements taken during the first three years en route to Mercury will be given.