LADEE Options

[Paolo]

I thought it was time to start a new topic on NASA's next Moon mission
incidentally, there is a new mission update out today

[Paolo]

one new paper on LADEE results in today's Science (and it appears to be in open access!):

How surface composition and meteoroid impacts mediate sodium and potassium in the lunar exosphere

Despite being trace constituents of the lunar exosphere, sodium and potassium are the most readily observed species due to their bright line emission. Measurements of these species by the Ultraviolet and Visible Spectrometer (UVS) on the Lunar Atmosphere and Dust Environment Explorer (LADEE) have revealed unambiguous temporal and spatial variations indicative of a strong role for meteoroid bombardment and surface composition in determining the composition and local time dependence of the Moon’s exosphere. Observations show distinct lunar day (monthly) cycles for both species as well as an annual cycle for sodium. The first continuous measurements for potassium show a more repeatable variation across lunations and an enhancement over KREEP (Potassium Rare Earth Elements and Phosphorus) surface regions, revealing a strong dependence on surface composition.

see also the perspective article (also in open access):

Sampling the Moon's atmosphere

In H. G. Wells' 1901 science fiction classic The First Men in the Moon, two protagonists, English businessman Mr. Bedford and the eccentric physicist Dr. Cavor, knock back a special enervating concoction designed to expand their lungs, followed by the requisite fortifying brandy, before venturing onto the Moon's surface to breathe the rarefied lunar atmosphere. Even more tenuous than Wells' imagined environment, the lunar exosphere is an atmosphere so thin that atoms never collide, bounded on one side by the lunar surface and extending thousands of kilometers out into space. This low-density envelope results from a balance among the influx of material from the Sun, outgassing from the Moon's interior, delivery from meteoritic bombardment, and the loss of material to space as well as recycling in the lunar surface (see the figure). The precise formula for the formation of the lunar exosphere is unknown, but recent data from orbital spacecraft are being used to delineate the relative contributions from different processes. On page 249 of this issue, Colaprete et al. (1) report measurements of sodium and potassium (Na and K) in the lunar exosphere based on observations from the Ultraviolet and Visible Spectrometer (UVS) aboard NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE), which acquired continuous dayside and nightside measurements of exospheric Na and K over multiple lunar orbits.