On the Possibility of Asteroid Magnetospheres

Paleomagnetic measurements of meteorites suggest that their parent planetesimals were magnetized by core dynamos or by the magnetic field in the solar nebula. We therefore expect that some asteroids have large-scale magnetic fields that could be probed by present and future spacecraft. In particular, the Psyche mission will measure the magnetic field in orbit around the metallic asteroid (16) Psyche, the Mobile Asteroid Surface Scout (MASCOT) on Hayabusa 2 will measure the magnetic field on the surface of carbonaceous asteroid (162173) Ryugu, and both OSIRIS-REx and Hayabusa 2 will return carbonaceous asteroid samples to Earth. Depending on the magnetization intensity within an asteroid, distinct types of interactions with the surrounding solar wind and its magnetic field are expected.

In this presentation, we explore the possibility of the formation and detection of asteroid magnetospheres, focusing in particular on metallic, highly magnetized asteroids. We present a theoretical examination of some possibly observable magnetospheric phenomena, such as a bow shock, current systems, and solar wind driven magnetic activity. To study the range of possible magnetospheric environments of such a body, we performed three-dimensional hybrid simulations of the interaction of different solar wind conditions with different body properties, to assess the resulting magnetic field configurations and charged particle environments. We compare our results to the interaction of the solar wind with other types of asteroids (such as a non-magnetized metallic asteroid and a non-metallic asteroid), and with other planetary magnetospheres.