![lro quickmap lro quickmap](https://www.lroc.asu.edu/news/uploads/eclipse2_annotated.sm2.png)
These anomalies reside on the nearside of the Moon within the southeastern Oceanus Procellarum and northwestern Mare Nubium, coincident with regions that have been observed to be photometrically anomalous at visible wavelengths.
![lro quickmap lro quickmap](https://www.lroc.asu.edu/news/uploads/LROCiotw/NAC_DTM_FRESH1_COLOR_thumb.png)
The Lyman Alpha Mapping Project has detected five discrete low-albedo anomalies in Lyman-α (Ly-α 121.6 nm) nighttime reflectance maps. The low albedos in the PSRs may also result from extreme charging effects inside the PSRs, causing lofting and redeposition of dust, as well as dielectric breakdown, which would act to increase regolith porosity. However, our analysis of the present data set was unable to uniquely identify its role. Thermal cycling might be a process that reduces porosity in regions of the crater exposed to a wide range of temperatures, thus increasing their albedos across the entire wavelength range. These PSRs are extremely cold regions with very minor thermal cycling. We conclude that the low PSR albedos correspond to high regolith porosity in the PSRs. Amundsen's PSRs, however, receive no direct solar illumination and very little solar wind flux and have a lower albedo across Lyman Alpha Mapping Project's entire band pass (57–197 nm) than illuminated regions of the crater.
![lro quickmap lro quickmap](http://lroc.sese.asu.edu/news/uploads/slipher_thumb.png)
We find that regions of the surface that receive large amounts of solar illumination and solar wind flux (e.g., the southern terrace walls) display high Lyman-α albedos and blue spectral slopes in the 175–190-nm region, indicative of increased regolith maturity due to solar wind weathering and thermal cycling. Using data from the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project, we investigate signatures of space weathering in different regions of Amundsen. Amundsen's equator-facing terrace walls are highly illuminated while the northern side of the crater has permanently shaded regions (PSRs). The lunar South Pole crater Amundsen is a prime location to study the effects of space weathering in the far ultraviolet. These maps represent a unique view into a relatively unexplored region of the spectrum and showcase the ability to perform compositional mapping and mineral identification using FUV remote-sensing measurements. Corrected LAMP maps show good correlation with lunar FeO, plagioclase, and bulk silicate abundance maps for moderate- to high-iron regions, indicating a sensitivity in the LAMP data to differences in mineral composition in those regions. After performing the correction, the LAMP maps more accurately represent the FUV lunar surface in the context of composition. Here we utilize a correction based on the optical maturity parameter to remove large-scale immaturity features from LAMP spectral slope and band ratio maps.
![lro quickmap lro quickmap](http://lroc.sese.asu.edu/news/uploads/iridum_mosaic_topo_str.png)
This can lead to uncertainties in the interpretation of features that appear in maps created using LAMP data from this wavelength range. This supports previous findings that determined that the rays from these craters are composed of highlands material excavated from beneath the maria and subsequently weathered to maturity.įar-ultraviolet (FUV) observations by the Lunar Reconnaissance Orbiter Lyman Alpha Mapping Project (LAMP) have shown that the lunar surface reflectance in the ultraviolet is sensitive to changes in both composition and maturity at wavelengths >170 nm. We also find that ejecta blankets from large maria craters (e.g., Copernicus and Aristillus) have a similar Off/On ratio to the mature background highlands. The lower Off/On ratio is likely due to the increased glass component of the regolith at these highlands regions, which would act to increase absorption at Off‐band wavelengths. Some large young highlands craters (e.g., Tycho, Jackson, Giordano Bruno, and Necho) display lower ratio halos around the crater cavity, at regions where previous studies have suggested abundant impact melt exists. The Off/On ratio of the highlands crater rays decreases linearly over time (0.095 per 100 My), and we use this trend to estimate the age of Jackson crater (~152 My). We find that crater rays from a survey of the largest Copernican‐age craters have high Off‐band (155–190 nm)/On‐band (130–155 nm) albedo (Off/On) LAMP product ratios, consistent with immature regolith and low amounts of submicroscopic iron. Because LAMP is sensitive to the uppermost layer of the lunar surface and regolith grains, it is ideal for characterizing regolith maturity and space weathering products such as submicroscopic iron. Using data from the Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP), we investigate the spectral properties of rayed craters in the far‐ultraviolet (FUV).