The Evolution of a Spacecraft‐Generated Lunar Exosphere

Abstract

Understanding how spacecraft alter planetary environments can offer important insights into key physical processes, as well as being critical to planning mission operations and observations. In this context, it is important to recognize that almost any powered lunar landing will be an active volatile release experiment, due to the release of exhaust gases during descent. This presents both an opportunity to study the interaction of volatiles with the lunar surface and a need to predict how nonindigenous gases are dispersed, and how long they persist in the lunar environment. This work investigates these questions through numerical simulations of the transport of water vapor during a nominal lunar landing and for two lunar days afterward. Simulation results indicate that the water vapor component of spacecraft exhaust is globally redistributed, with a significant amount reaching permanently shadowed regions (cold traps) near the closest pole, where temperatures are sufficiently low that volatiles may remain stable over geological timescales. Exospheric evolution and surface deposition patterns are highly sensitive to desorption activation energy, providing a means to constrain this critical parameter through landed or orbital measurements during future missions. Contamination of cold traps by exhaust gases is likely to scale with exhaust mass and proximity of the landing site to the poles. Exhaust propagation is perhaps the most widespread and long‐lived impact of spacecraft operations on a nominally airless solar system body and should be a key consideration in mission planning and in interpreting measurements made by landed lunar missions, particularly at near‐polar regions.

What Should We Do with Our Moon?: Ethics and Policy for Establishing International Multiuse Lunar Land Reserves

“…On our moon baseline ecology reserves can purvey tremendously valuable information regarding the impacts of an expanded human presence as well as the dynamics of lunar ecological systems in themselves. If we keep baseline ecology reserves separate from transportation launch areas, we can even reduce the predicted negative scientific blows wrought by lunar rocketry [39]. As a plus, by preserving ecologies without undue interference, these baseline ecology reserves further aid the protection of important space-age historical spots as much as possible like they were at the time that they made history.…”

Seasons of Ice: Water Ice Migration and Seasonal Transient Shadow at the Lunar Poles

“…However, smaller initial deposits close enough to the surface to interface with the transient ice deposits will not survive in that interface zone for more than a few months, and even an infinitely deep initial ice deposit is likely to be rapidly heated and removed beyond the interface zone. Therefore, this interaction is unlikely to occur in the absence of significant modification from very recent impact gardening, recent significant deposition of ice buried underneath ejecta from a nearby impact, or contamination introduced into the system by rocket exhaust or other human exploration activities (Costello et al, 2018(Costello et al, , 2020Farrell et al, 2022;Hurley et al, 2012;Prem et al, 2015Prem et al, , 2020.…”

Water Group Exospheres and Surface Interactions on the Moon, Mercury, and Ceres

“…That would effectively shut down lateral transport by the exosphere. Long-term exospheric monitoring by orbital and surface instrumentation could contribute to addressing this question (e.g., Prem et al 2020). Another partially unresolved question is the significance of isotopic fractionation during the transport of water.…”