# A Model of the Primordial Lunar Atmosphere

## TL;DR

This paper presents the first quantitative model of the primordial lunar atmosphere, considering early solar and Earth radiation effects, magma ocean interactions, and resulting atmospheric dynamics that influenced lunar surface and volatile distribution.

## Contribution

It introduces a novel coupled model of the early lunar atmosphere and magma ocean, highlighting the impact of radiative environment and atmospheric winds on lunar surface and volatile distribution.

## Key findings

- Lunar atmosphere was primarily Earth-side, with pressures from 10^4 to 10^2 pascals.
- Supersonic winds transported volatiles and generated magma ocean waves.
- Atmospheric asymmetries influenced temperature distribution and ocean flow.

## Abstract

We create the first quantitative model for the early lunar atmosphere, coupled with a magma ocean crystallization model. Immediately after formation, the moon's surface was subject to a radiative environment that included contributions from the early Sun, a post-impact Earth that radiated like a mid-type M dwarf star, and a cooling global magma ocean. This radiative environment resulted in a largely Earth-side atmosphere on the Moon, ranging from $\sim$10$^4$ to $\sim$10$^2$ pascals, composed of heavy volatiles (Na and SiO). This atmosphere persisted through lid formation and was additionally characterized by supersonic winds that transported significant quantities of moderate volatiles and likely generated magma ocean waves. The existence of this atmosphere may have influenced the distribution of some moderate volatiles and created temperature asymmetries which influenced ocean flow and cooling. Such asymmetries may characterize young, tidally locked rocky bodies with global magma oceans and subject to intense irradiation.