Ancient Volcanically-Induced Transient Lunar Atmosphere and its Effect on Polar Volatiles
Abstract
The issue of polar water and other volatiles has become an important consideration in relation to the future manned missions to the Moon. While observations provide some information on volatile distribution, their origin and history are still poorly understood. Three sources of volatiles are typically considered: the solar wind, the impactors (such as meteorites or comets) and the volcanic outgassing. It was recently shown [1] that volcanic outgassing during the peak of Moon's volcanic activity ~3.5 Ga, if happened over a relatively short time, could produce enough water to explain its current abundance and at the same time produce a transient atmosphere as thick as on modern Mars. Such atmosphere, if existed, would control the delivery of volatiles from the maria to polar regions, where they could be trapped in Permanently Shadowed Regions or buried under the regolith and thus preserved until modern day. A preliminary study of such relatively "thick" atmosphere was done in [2]. More recent research [3] suggests that due to long periods between eruptions such atmosphere could be a few orders of magnitude thinner.
Here we use ROCKE-3D general circulation model [4] to study such transient atmospheres for a wider parameter space. We consider the cases of surface pressure from 10 mbar to 0.01 mbar, zero and non-zero obliquities, and several atmospheric compositions. The atmospheric compositions were chosen according to the results of our 1-D chemistry model based on initial contents of outgassed species and preliminary atmospheric conditions provided by ROCKE-3D. We investigate the stability of such atmospheres and conjecture on their effect on volatile distribution. The study of isotopic composition of polar volatile deposits in future missions will further constrain the results of this research. References: [1] Needham & Kring 2017, EPSL 478, 175. [2] Aleinov et al. 2019, GRL, 46(10), 5107. [3] Wilson et al. 2019, LPSC 2019, Abstract 1343. [4] Way et al. 2017, Astrophys. J. Supp. Series, 231(1), 12.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P34B..08A
- Keywords:
-
- 6205 Asteroids;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6230 Martian satellites;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 6250 Moon;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS