3-D Modeling of a Secondary Ancient Lunar Atmosphere: The Effect on Volatile Distribution

DESCRIPTION: It has been known for some time (Stern 1999) that lunar volcanic outgassing 4-3 Gya was capable of producing thin transient collisional atmospheres. Recent research (Needham & Kring 2017) shows that such atmospheres could reach the density of modern Mars. Understanding the formation, evolution, and ultimate fate of such secondary lunar atmospheres are key to understanding the present-day distribution of volatiles on the Moon. Volatiles would have been initially deposited, migrated over time due to a number of processes (e.g. polar wander, obliquity changes due to impacts, micrometeorite mixing, etc.), and lost to space through several possible escape mechanisms (Kulikov 2007). Finding where these volatiles may be located (both geographically and at what burial depth), and identifying patterns in their distributions, will be critical for future robotic and human exploration of the Moon. This work also represents a step towards understanding tenuous atmospheres on other small bodies.