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UID:seminar-19193@epss.ucla.edu
DTSTAMP:20261005T104358Z
DTSTART:20261002T153000Z
DTEND:20261002T163000Z
SUMMARY:Space Physics (293): Lucas Liuzzo &#8211\; Energetic particle access to the Moon: Context for the solar radiation environment relevant for crewed missions
LOCATION:3853 Slichter Hall
DESCRIPTION:Speaker: Dr. Lucas Liuzzo

Affiliation: Space Sciences Laboratory\, UC Berkeley

Date: Friday\, October 2\, 2026

Time: 3:30 PM

Zoom/Meeting Link: https://ucla.zoom.us/j/97178405473?pwd=WMx7ClxaSw38JatXhzPshjC5G0O1Um.1



Abstract
Solar energetic particles pose significant hazards to space exploration and habitation. In the context of the Moon\, understanding the access of these high-energy particles to the lunar environment is critical when studying the composition and charging of the surface\, quantifying energy deposition at depth\, and when considering the planned exploration during crewed and robotic missions.

During its orbit around Earth\, the Moon is exposed to the solar wind during approximately two-thirds of the time. Solar energetic particles—typically generated by solar flares or at the shock front of an expanding interplanetary coronal mass ejection (ICME)—stream outward throughout the solar system and precipitate directly onto the lunar dayside surface. However\, we have identified a scenario in which flare-accelerated energetic particles first pass the lunar dayside\, encounter a distant ICME located beyond Earth\, reflect and travel sunward toward the lunar nightside. This mechanism represents an additional\, underappreciated hazard for assets located on the lunar nightside and highlights the importance of accurately characterizing past space weather activity when predicting the impact of ongoing (or future) events.

For the remaining one-third of its orbit\, the Moon is embedded deep within the tail of Earth’s magnetosphere. Although the strong terrestrial magnetic field prevents high-energy particles from reaching Earth’s surface\, the Moon does not receive the same protection while located within the terrestrial magnetotail. Instead\, we show that the high-energy ions and electrons readily penetrate the tail along field lines that are open to the solar wind far downstream of the Moon and we highlight the overall lack of shielding from these particles at any phase of the lunar orbit during extreme solar energetic particle events. Our findings provide context for understanding access of these high-energy solar particles to the lunar surface and are relevant for the safety of astronauts during the upcoming missions to explore the lunar environment.
URL:https://epss.ucla.edu/space-physics-293-lucas-liuzzo-solar-energetic-particles-seps-at-the-moon/
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