Upstream Ultra-Low Frequency Waves Observed by MESSENGER's Magnetometer: Implications for Particle Acceleration at Mercury's Bow Shock

<p>In this work we perform the first statistical analysis of the main properties of waves observed in the 0.05–0.41 Hz frequency range in the Hermean foreshock by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Magnetometer. Although we find similar polarization properties to the '30 s' waves observed at the Earth's foreshock, the normalized wave amplitude (∼0.2) and occurrence rate (∼0.5%) are much smaller. This suggests significant lower backstreaming proton fluxes, due to the relatively low solar wind Alfvenic Mach number around Mercury. These differences could also be related to the relatively smaller foreshock size and/or more variable solar wind conditions. Furthermore, we estimate that the speed of resonant backstreaming protons in the solar wind reference frame (likely source for these waves) ranges between 0.95 and 2.6 times the solar wind speed. The closeness between this range and what is observed at other planetary foreshocks suggests that similar acceleration processes are responsible for this energetic population and might be present in the shocks of exoplanets.</p>

Global hybrid simulations of highly compressed magnetosphere events at Mercury

<p><span lang="EN-US">The highly compressed magnetosphere (HCM) events at Mercury observed by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have been investigated using the global hybrid simulation LatHyS. The HCM events occur due to the interactions with coronal mass ejections (CMEs) or high-speed streams (HSSs) and previous studies indicate that not only the reconnection-driven erosion but also the induced currents in the inner core have an important role in the variation of the dayside magnetosphere of Mercury. However, the effects of the presence of planetary ions on Mercury’s system have not been well discussed. In this study, we mainly focus on the presence of planetary ions that are self-consistently produced from the exosphere by several ionization processes under extreme solar wind conditions and discuss their role on the structure and dynamics of Mercury’s magnetosphere.</span></p>

VALIDATION OF THE STEREO OBSERVATION STRATEGY OF SIMBIO-SYS USING A VIRTUAL SIMULATOR

The Spectrometer and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIO-SYS) is a suite of three independentoptical heads that will provide images and spectroscopic observations of the Mercury surface. With the approaching of BepiColombo to Mercury, the definition of the observation strategies of each instrument is becoming mandatory also for testing the operation procedures in terms of feasibility and stereo performance. The use of synthetic images and a customized simulator have been considered a powerful way to accomplish this test. This simulation system allows to investigate all the possible stereo configurations (different stereo angles and different image combinations) with the opportunity to evaluate the operational feasibility thanks to the evaluation of the final stereo products. Working with a simulated dataset allows to control most of the geometrical aspects (both the projection model definition and the observation geometry) suggesting with the analysis of the stereo products the better configuration to be applied and to be considered in the definition of the observation strategy. Editorial note: The article originally published here accidentally contained copyrighted information. For this reason, both authors and editor agreed to retract the original article and replace it with a revised version. The editors confirm that the scholarly content is not affected and remains a valuable contribution to the proceedings. Should you have downloaded the original version of this article (prior to 9 October 2020), you are kindly asked to delete it and refrain from any redistribution. Thank you, the editors.

Particle Induced X-ray Emission at Mercury and the Moon.

<p>Mercury and the Moon are examples of terrestrial bodies which lack an atmosphere and therefore have surfaces which interact directly with the space environment. Thus the surfaces can be reprocessed by plasma impact, and in the process can emit X-rays via the Particle Induced X-ray Emission (PIXE) process. We will present and review existing measurements, particularly from SMART-1 and Chandrayaan at the Moon, and Messenger and Mercury, in order to predict opportunities for new science at Mercury by BepiColumbo. We will present predictions of PIXE signals from different regions of the Mercury surface, and examine the possibility of using the signal for direct diagnosis of particle interactions with the surface. These include the auroral signatures of substorm like behaviour, and interactions with coronal mass ejections.</p>