Johns Hopkins University | Applied Physics Laboratory | 2020 Aug 14
A new study ... shows that exhaust from a mid-sized lunar lander can quickly spread around the Moon and potentially contaminate scientifically vital ices at the lunar poles.Simulation showing how water vapor from a lander’s exhaust spreads throughout
the Moon’s atmosphere (shades of blue and red, with warmer tones being denser)
and across its surface (shades of purple, with lighter tones being denser) in 24
hours. The exhaust from a landing site near the Moon’s south pole takes only a
few hours to spread to the other pole. Credit: JHU APL
Computer simulations of water vapor emitted by a 2,650-pound (1,200-kilogram) lander — about a quarter of the dry mass of the Apollo Lunar Module — touching down near the Moon’s south pole showed exhaust takes only a few hours to disperse around the entire Moon. From 30% to 40% of the vapor persisted in the lunar atmosphere and surface two months later, and roughly 20% would ultimately freeze out near the poles a few months after that.
Those results ... show that researchers’ interest in studying the native ices in the Moon’s poleward craters — ices that may date back several billion years — will need to be carefully considered during increased efforts to return humans to the Moon.
Dealing with spacecraft exhaust on the Moon isn’t a new problem. Researchers appreciated this issue during NASA’s Apollo missions in the ‘60s and ‘70s, when they developed early models to predict the spread of exhaust throughout the lunar atmosphere and contamination of the surface. ...
During the Apollo era, most of the interest was in collecting lunar samples. While that’s still true today, the more recent discovery of ices preserved in permanently shadowed craters near the lunar poles has shifted scientific interest to understanding the origin and dispersion of water and other volatile molecules on the Moon’s surface and in its thin atmosphere. ...
The Evolution of a Spacecraft‐Generated Lunar Exosphere ~ Parvathy Prem et al
- Journal of Geophysical Research: Planets (online 11 Aug 2020) DOI: 10.1029/2020JE006464