Solar‐Storm/Lunar Atmosphere Model (SSLAM): An overview of the effort and description of the driving storm environment

Abstract

On 29 April 1998, a coronal mass ejection (CME) was emitted from the Sun that had a significant impact at Earth. The terrestrial magnetosphere became more electrically active during the storm passage. Less explored is the effect of such a storm on an exposed rocky body like our Moon. The solar‐storm/lunar atmosphere modeling effort (SSLAM) brings together surface interactions, exosphere, plasma, and surface charging models all run with a common driver – the solar storm and CME passage occurring from 1 to 4 May 1998. We present herein an expanded discussion on the solar driver during the 1–4 May 1998 period that included the passage of an intense coronal mass ejection (CME) that had >10 times the solar wind density and had a compositional component of He++ that exceeded 20%. During this time, the plasma mass flux to the exposed lunar surface increased by over 20 times compared to the nominal solar wind, to a value near 10−13 kg/m2‐s. Over a two day CME passage by the Moon, this amount approaches 300 tons of added mass to the Moon in the form of individual proton and helium ions. Such an increase in ion flux should have a profound impact on sputtering loss rates from the surface, since this process scales as the mass, energy, and charge state of the incident ion. Associated loss processes were addressed by SSLAM and will be discussed herein.