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The lunar surface has a complex plasma environment due to incoming solar wind flux and charged micron-sized dust particles and the presence of solar ultraviolet (UV) radiation. UV resonance fluorescence of solar radiation provides a sensitive detection of major elemental constituents, such as H, H2, O, C, N, and noble gases in the tenuous daytime lunar atmosphere. Photoemission due to the solar UV radiation is the dominating process in the charging environment, creating a photoelectron “sheath.” Such detections were observed by LADEE UV spectrometer and the Apollo 17 UV spectrometer.

Early bombardment of the Moon by planetesimals, from geocentric and heliocentric orbits, are the possible cause of the lunar crustal thickness asymmetries. The Earth’s presence also causes the Moon to be bombarded non-uniformly. A very early, yet intense bombardment like this could have redistributed lunar crustal materials, thinning certain lunar regions. This period is suggested to be < 3.9 Gyr ago.

Large basins across the lunar surface have observable positive gravity anomalies within the interiors, referred to as mass concentrations, or “mascons.” Some near-side mascons can be explained by flexural support of the mare basalts within the basins, like Orientale, that have excessive mascons. There are also some basins that exhibit masons but lack mare basalts. Lunar gravity and topography data are most often used to determine the morphology and gravity anomalies of the mascons.

The Moon’s origin and formation should be able to explain the current physical, dynamical, chemical, and internal thermal states. While the Giant Impactor Theory is the leading theory, we must also look into the earlier variations of lunar origins. This includes variants on three main possible scenarios: capture, rotational disruption, and co-accretion.

Rock boulders are considerably typical of airless rocky bodies throughout the inner solar system, so their environments prove useful to understanding the rates of surface-modification processes and “survival times” of these boulders. On the Moon, there are meter-sized boulders on the rims of small lunar carters of some known age, so modeling the rock destruction is applied. Interior and exterior stresses must be considered, including thermal day-night cycling of the regolith and sub-regolith, and solar wind.

The Selenological and Engineering Explorer (SELENE), also known as Kaguya, was the second Japanese lunar orbiter spacecraft, following the Hiten probe. The spacecraft launch in September 2007 and ended in June 2009. Two sub-satellites and a suite of instruments on the Main orbiter mapped across the Moon, exploring several science objectives relating to the geologic history of the lunar surface, including new data pertaining to magnetic anomalies and GRS data with higher spatial resolution were acquired.

The Hiten mission (formerly the MUSES-A) was the first space engineering experimental satellite of the Institute of Space and Astronautical Science (ISAS) and was launched from Kagoshima Space Center (JKSC) in Japan in January 1990. After the successful insertion into a highly elliptical orbit around the Earth, the Hiten mission carried out several objectives to demonstrate space technologies for swing-by (or gravity assist) techniques and insertion of a sub-satellite into orbital space around the Moon. The results from these engineering missions have also led to follow-on missions, including aerobraking techniques and an excursion to the Lagrange points of the Earth-Moon system.