Maximum Energies of Trapped Particles Around Magnetized Planets and Small Bodies

Rona Oran, Benjamin P. Weiss, Maria De Soria Santacruz-Pich, Insoo Jun, David J. Lawrence, Carol A. Polanskey, J. Martin Ratliff, Carol A. Raymond, Jodie B. Ream, Christopher T. Russell, Yuri Y. Shprits, Maria T. Zuber, Linda T. Elkins-Tanton

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Energetic charged particles trapped in planetary radiation belts are hazardous to spacecraft. Planned missions to iron-rich asteroids with possible strong remanent magnetic fields require an assessment of trapped particles energies. Using laboratory measurements of iron meteorites, we estimate the largest possible asteroid magnetic moment. Although weak compared to moments of planetary dynamos, the small body size may yield strong surface fields. We use hybrid simulations to confirm the formation of a magnetosphere with an extended quasi-dipolar region. However, the short length scale of the field implies that energetic particle motion would be nonadiabatic, making existing radiation belt theories not applicable. Our idealized particle simulations demonstrate that chaotic motions lead to particle loss at lower energies than those predicted by adiabatic theory, which may explain the energies of transiently trapped particles observed at Mercury, Ganymede, and Earth. However, even the most magnetized asteroids are unlikely to stably trap hazardous particles.

Original languageEnglish (US)
Article numbere2021GL097014
JournalGeophysical Research Letters
Issue number13
StatePublished - Jul 16 2022


  • (16) Psyche
  • Psyche mission
  • asteroid magnetospheres
  • chaotic motion
  • energetic particles
  • hybrid simulations

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)


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