Vesta's surface composition provides insights on its internal structure, geological evolution, and space environment. The bulk igneous composition, the link to the howardite–eucrite–diogenite (HED) meteorites, and the differentiation into a crust and a mantle were confirmed by telescopic observations and by the Dawn mission. This chapter presents several key topics. The distribution of indigenous materials helps in understanding the structure and mineralogy of the crust and the thickness of the mantle as an insight to the geological evolution and history of the whole body. Hydroxylated, low-albedo areas indicate exogenous materials and widespread contamination of the surface by carbonaceous chondrites; this main result from the Dawn mission also has implications for the collisional history of Ceres. Finally, the characterization of surficial processes on Vesta clarifies the role of space weathering and lateral mixing. The surface composition studied from telescopic observations, geochemical measurements of the HED meteorites, and from the Dawn mission at Vesta is based on reflectance imaging spectroscopy, high-resolution imagery, and elemental data from gamma-ray and neutron spectroscopy. This chapter includes analyses of data from the Visible and InfraRed mapping spectrometer that benefited from improved instrument calibrations developed after the Dawn mission to Vesta and Ceres.

Advanced spectroscopic sensors recently flown to the Moon have revealed unexpected discoveries about Earth’s nearest neighbor as well as provided detailed insights and constraints about how early crust evolves on an airless planetary body. Discussed here are (a) global assessment of the variety and distribution of major lunar mineral components and lithologies; (b) some of the remarkable new findings, such as the pervasive presence of OH across the surface and new rock types identified (Mg-spinel anorthosite) that are not identified in current lunar samples; and (c) expectations for the future as additional modern sensors provide a stronger foundation for remote compositional analysis of the Moon. Spectroscopic data continue to provide the cornerstone for identifying and understanding the regional and global character of lunar compositional variations and document key products and processes of crustal evolution.

An ever-increasing number of laboratory facilities are enabling in situ spectral reflectance measurements of materials under conditions relevant to all the bodies in the Solar System, from Mercury to Pluto and beyond. Results derived from these facilities demonstrate that exposure of different materials to various planetary surface conditions can provide insights into the endogenic and exogenic processes that operate to modify their surface spectra, and their relative importance. Temperature, surface atmospheric pressure, atmospheric composition, radiation environment, and exposure to the space environment have all been shown to measurably affect reflectance and emittance spectra of a wide range of materials. Planetary surfaces are dynamic environments, and as our ability to reproduce a wider range of planetary surface conditions improves, so will our ability to better determine the surface composition of these bodies, and by extension, their geologic history.