Dynamics and structure of the lunar mini-magnetospheres

The Moon does not have either a magnetic field or an atmosphere. The solar wind directly impacts the surface.

Many space plasma physicists believe that the Moon is a “boring” object for space plasma physics where not much happens. It is not!

The Moon is not “boring” for space plasma physics but demonstrates a zoo of exciting phenomena and complex interactions not fully or indeed at all understood, but nevertheless important for understanding the Moon as a celestial body.

Even the fundamental problem of the origin of lunar water is relevant to space physics because the water may have come from the solar wind reacting with the surface.

With this project we intent to study lunar mini-magnetospheres, full or partial voids of the solar wind associated with local magnetization of the lunar crust.The typical scale of a mini-magnetosphere is on the order of 100 km and up to 10-30 km height. This is then in the sub ion inertial range and also falls in between the ion and electron gyro-radii.

By shielding the surface from the solar wind, mini-magnetospheres affect the surface features such as albedo, water content, and dust distribution. Due to their small size studying these structures from orbiters is a difficult task.

Pioneering measurements conducted by IRF on the Indian Chandrayaan-1 mission opened the possibility of exploring mini-magnetospheres remotely using imaging of backscattered neutrals (energetic neutral atom (ENA) imaging).

We will use this novel technique, combined for the first time with in-situ ion measurements on Chandrayaan-1, to investigate variability of the mini-magnetospheres created by the cluster of magnetic anomalies at the Imbrium antipode with the solar zenith angle as well as when the Moon travels through the terrestrial magnetosphere.

We aim to experimentally establish the physics, which governs the structure and dynamics of the mini-magnetospheres.A currently operational ENA detector at the rim of the Imbrium antipode onboard the Chinese Chang’E-4 rover enables investigation of the variability of solar wind flux reaching the surface directly.

Using Chang’E-4 observations combined with the earlier context measurements from Chandrayaan-1, we will establish the dependence of the proton fluxes on the surface in the Imbrium antipode area on upstream conditions and generalize these findings for other locations.To advance understanding of the physics behind the experimental results we will model the relevant cases of the solar wind interactions with magnetic anomalies using hybrid models run on Graphics Processing Units (GPU) and Swedish high performance computer clusters at Umeå and Linköping universities.

The main goal of the project to answer two overarching science questions:How does a lunar mini-magnetosphere structure respond to variable upstream conditions?How do mini-magnetospheres affect the solar wind flow on the lunar surface?We apply for a 2-year PostDoc position at IRF. The expected outcome of the project is three (3) publications in peer-reviewed scientific journals with open access.