Solar-wind electron precipitation on weakly magnetized bodies: the planet Mercury

Mercury is the archetype of a weakly magnetized, airless, telluric body immersed in the solar wind. Due to the lack of any substantial atmosphere, the solar wind directly precipitates on Mercury's surface. Using a 3D fully-kinetic self-consistent plasma model, we show for the first time that solar-wind electron precipitation drives (i) efficient ionization of multiple species (H, He, O and Mn) in Mercury's neutral exosphere and (ii) emission of X-rays from the planet's surface. This is the first, independent evidence of X-ray auroras on Mercury using a numerical approach.Comment: Submitted to Physical Review Letter

The BepiColombo Environment Radiation Monitor, BERM

The BepiColombo Environment Radiation Monitor (BERM) on board the European Space Agency's Mercury Planetary Orbiter (MPO), is designed to measure the radiation environment encountered by BepiColombo. The instrument measures electrons with energies from similar to 150 keV to similar to 10 MeV, protons with energies from similar to 1.5 MeV to similar to 100 MeV, and heavy ions with Linear Energy Transfer from 1 to 50 MeV.mg(-1).cm(2). BERM is operated continuously, being responsible for monitoring the radiation levels during all phases of the mission, including the cruise, the planetary flybys of Earth, Venus and Mercury, and the Hermean environment. In this paper, we describe the scientific objectives, instrument design and calibration, and the in-flight scientific performance of BERM. Moreover, we provide the first scientific results obtained by BERM during the BepiColombo flyby of Earth in April 2020, and after the impact of a solar energetic particle event during the cruise phase in May 2021. We also discuss the future plans of the instrument including synergies with other instruments on the BepiColombo and on other missions.Peer reviewe

BepiColombo Venus Flyby Science Operations Feasibility Analysis

BepiColombo is an interdisciplinary ESA mission to explore the planet Mercury in cooperation with the Japan Aerospace Exploration Agency (JAXA). The mission consists of 2 spacecraft, ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO) that carry in total 17 science payloads for the investigation of Mercury’s structure, interior, composition, morphology, formation, evolution and environment. The Mercury Composite Spacecraft (MCS) made of MPO, MMO, a Mercury Transfer Module (MTM) and a sunshield (MOSIF) will be launched on an escape trajectory that will bring it into heliocentric orbit on its way to Mercury. During the cruise of 7.2 years toward the inner part of the Solar System, BepiColombo will make 1 flyby to the Earth, 2 to Venus, and 6 to Mercury. Only part of its payload will be obstructed by the sunshield and the cruise spacecraft configuration, so that the flybys will allow operations of many instruments, like: spectrometers at many wavelengths, accelerometer, radiometer, ion and electron detectors. A scientific working group (VFBWG, Venus Fly-by Working Group) has recently formed inside the BepiColombo community to identify potentially interesting scientific cases and to promote collaborations during the Venus flybys. At the same time, analyses of science operations requests has been carried out by the Science Ground Segment (SGS) at ESAC and the Operational Ground Segment (OGS) at ESOC to help scientists in the comprehension of feasibility of proposed investigations. The analysis of science observations includes special spacecraft pointing feasibility analysis taking into account the attitude constraints. During interplanetary cruise and outside electric propulsion, the default attitude of MCS is with +Y axis pointed to the Sun. The spacecraft attitude is then adjusted by ground around the sun line such that the angular momentum loading is minimized while ground contact is maximized during ground station passes. For the short duration of scientific interest around the Venus closest approaches, however, the need for angular momentum load minimization can be relaxed and it is possible to offset the Sun direction in the spacecraft composite +YZ plane. The SGS at ESAC developed a tool that allows to check the possibility of observing Venus in different spacecraft configurations for different instruments, for example finding out when Venus is inside a given instrument FoV. With that tool and based on the scientific instruments pointing requests, candidate pointing timelines were extracted, indicating that it is possible to find a suitable spacecraft composite attitude to provide observing opportunities to most instruments requiring specific spacecraft pointing. In addition, the OGS at ESOC analysed the impact of the received scientific requests on power balance, thermal balance and data return and found well within the as-designed capability of the spacecraft. This paper includes a summary of the scientific requests, the analysis carried out by both SGS and OGS and the results of the analysis

The BepiColombo Environment Radiation Monitor, BERM

The BepiColombo Environment Radiation Monitor (BERM) on board the European Space Agency's Mercury Planetary Orbiter (MPO), is designed to measure the radiation environment encountered by BepiColombo. The instrument measures electrons with energies from similar to 150 keV to similar to 10 MeV, protons with energies from similar to 1.5 MeV to similar to 100 MeV, and heavy ions with Linear Energy Transfer from 1 to 50 MeV.mg(-1).cm(2). BERM is operated continuously, being responsible for monitoring the radiation levels during all phases of the mission, including the cruise, the planetary flybys of Earth, Venus and Mercury, and the Hermean environment. In this paper, we describe the scientific objectives, instrument design and calibration, and the in-flight scientific performance of BERM. Moreover, we provide the first scientific results obtained by BERM during the BepiColombo flyby of Earth in April 2020, and after the impact of a solar energetic particle event during the cruise phase in May 2021. We also discuss the future plans of the instrument including synergies with other instruments on the BepiColombo and on other missions

BepiColombo Science Investigations During Cruise and Flybys at the Earth, Venus and Mercury

The dual spacecraft mission BepiColombo is the first joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) to explore the planet Mercury. BepiColombo was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, and a sunshield. BepiColombo cruise trajectory is a long journey into the inner heliosphere, and it includes one flyby of the Earth (in April 2020), two of Venus (in October 2020 and August 2021), and six of Mercury (starting from 2021), before orbit insertion in December 2025. A big part of the mission instruments will be fully operational during the mission cruise phase, allowing unprecedented investigation of the different environments that will encounter during the 7-years long cruise. The present paper reviews all the planetary flybys and some interesting cruise configurations. Additional scientific research that will emerge in the coming years is also discussed, including the instruments that can contribute

Photolatent Tertiary Amines – A New Technology Platform for Radiation Curing

The lack of efficient photolatent amine catalysts has so far prevented the use of base-catalyzed formulations in radiation curing. The development of two new photocatalysts which release 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) or tertiary amines upon irradiation opens new opportunities for this technology. Photolatent DBN is used for crosslinking processes where strong bases are required as catalyst, such as coatings crosslinked via the Michael addition reaction, while a tertiary amine efficiently catalyzes reactions involving more acidic compounds. A UV-A curable car refinish clear lacquer has been developed as a first example of a commercial formulation using a photolatent amine as catalyst