1] Although of great interest for science and resource utilization, the Moon's permanently shadowed regions (PSRs) near each pole present difficult targets for remote sensing. The Lyman Alpha Mapping Project (LAMP) instrument on the Lunar Reconnaissance Orbiter (LRO) mission is able to map PSRs at far-ultraviolet (FUV) wavelengths using two faint sources of illumination from the night sky: the all-sky Ly a glow produced as interplanetary medium (IPM) H atoms scatter the Sun's Ly a emissions, and the much fainter source from UV-bright stars. The reflected light from these two sources produces only a few hundred events per second in the photon-counting LAMP instrument, so building maps with useful signal-to-noise (SNR) ratios requires the careful accumulation of the observations from thousands of individual LRO orbits. In this paper we present the first FUV albedo maps obtained by LAMP of the Moon's southern and northern polar regions. The results show that (1) most PSR regions are darker at all FUV wavelengths, consistent with their surface soils having much larger porosities than non-PSR regions (e.g., $70% compared to $40% or so), and (2) most PSRs are somewhat "redder" (i.e., more reflective at the longer FUV wavelengths) than non-PSR regions, consistent with the presence of $1-2% water frost at the surface. Citation: Gladstone, G. R., et al. (2012), Far-ultraviolet reflectance properties of the Moon's permanently shadowed regions,

The flyby measurements of the Cassini spacecraft at Saturn's moon Rhea reveal a tenuous oxygen (O(2))-carbon dioxide (CO(2)) atmosphere. The atmosphere appears to be sustained by chemical decomposition of the surface water ice under irradiation from Saturn's magnetospheric plasma. This in situ detection of an oxidizing atmosphere is consistent with remote observations of other icy bodies, such as Jupiter's moons Europa and Ganymede, and suggestive of a reservoir of radiolytic O(2) locked within Rhea's ice. The presence of CO(2) suggests radiolysis reactions between surface oxidants and organics or sputtering and/or outgassing of CO(2) endogenic to Rhea's ice. Observations of outflowing positive and negative ions give evidence for pickup ionization as a major atmospheric loss mechanism.

On 9 October 2009, the Lunar Crater Observation and Sensing Satellite (LCROSS) sent a kinetic impactor to strike Cabeus crater, on a mission to search for water ice and other volatiles expected to be trapped in lunar polar soils. The Lyman Alpha Mapping Project (LAMP) ultraviolet spectrograph onboard the Lunar Reconnaissance Orbiter (LRO) observed the plume generated by the LCROSS impact as far-ultraviolet emissions from the fluorescence of sunlight by molecular hydrogen and carbon monoxide, plus resonantly scattered sunlight from atomic mercury, with contributions from calcium and magnesium. The observed light curve is well simulated by the expansion of a vapor cloud at a temperature of ~1000 kelvin, containing ~570 kilograms (kg) of carbon monoxide, ~140 kg of molecular hydrogen, ~160 kg of calcium, ~120 kg of mercury, and ~40 kg of magnesium.

Planetary‐scale waves are thought to play a role in powering the yet unexplained atmospheric superrotation of Venus. Puzzlingly, while Kelvin, Rossby, and stationary waves manifest at the upper clouds (65–70 km), no planetary‐scale waves or stationary patterns have been reported in the intervening level of the lower clouds (48–55 km), although the latter are probably Lee waves. Using observations by the Akatsuki orbiter and ground‐based telescopes, we show that the lower clouds follow a regular cycle punctuated between 30°N and 40°S by a sharp discontinuity or disruption with potential implications to Venus's general circulation and thermal structure. This disruption exhibits a westward rotation period of ∼4.9 days faster than winds at this level (∼6‐day period), alters clouds' properties and aerosols, and remains coherent during weeks. Past observations reveal its recurrent nature since at least 1983, and numerical simulations show that a nonlinear Kelvin wave reproduces many of its properties.

[1] We present an analysis of Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) measurements of the dayside lunar surface at far-ultraviolet wavelengths. We use the strong 165 nm H 2 O absorption edge to look for diurnal variations in hydration. We find that diurnal variations in spectral slope are indeed present; they are superimposed on latitudinal and spatial variations related to composition and weathering. We use two different spectral regions (164-173 nm and 175-190 nm) to separate out these effects. Highlands and mare regions have distinct reflectance spectra, with mare regions being spectrally bluer than highlands regions, a consequence of the greater abundance of opaque minerals in mare regions. Bright ray terrains and areas known to be young such as Giordano Bruno crater, are found to be relatively spectrally flat or red in the far-UV; this is consistent with a lack of space weathering, which tends to make the far-UV spectrum bluer due to the spectral behavior of nanophase iron. Large-scale latitudinal variations in FUV slope are distinct and are likely due to a gradient in space weathering. The diurnal variation in hydration is consistent with a solar wind origin and with loss of H 2 O at temperatures above $320 K. Far-UV spectroscopy is thus shown to represent a viable method for mapping aqueous alteration, even on the dayside of the Moon, and potentially elsewhere in the solar system.