Speaker
Description
The lunar exosphere, first identified during the Apollo missions, is a tenuous, collisionless surface-bounded environment composed of species with distinct origins and transport behaviors. Helium is primarily supplied by solar wind implantation, whereas sodium is mainly released from the lunar surface through sputtering and photon-stimulated desorption. Because intermolecular collisions are negligible, particles follow ballistic trajectories between surface interactions. Observations from LRO/LAMP, LADEE/NMS, and ARTEMIS demonstrate a strong response of the helium exosphere to variations in solar wind alpha flux, while extreme conditions such as ICMEs can enhance sputtering rates by more than an order of magnitude within about an hour. To investigate these processes, we develop a time-dependent Monte Carlo model that includes multiple source and loss mechanisms and time-varying solar wind inputs, allowing us to simulate the production, transport, and evolution of the lunar helium and sodium exospheres under the extrem solar wind conditions.
| Participate the oral/poster presentation award competition | No |
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