The Moon's bright albedo markings, known as swirls, are defined by broad, bright, on-swirl areas separated by darker off-swirl lanes. Their formation mechanism has long been debated and is key for understanding the processing of the lunar surface, the mobility of the lunar soil particles, and the effects of the space environment on planetary surfaces. Here we present, for the first time, evidence that these features do not necessarily cross the surface without regard to topography or local terrain. Within portions of Mare Ingenii on the lunar far-side, brighter on-swirl areas have statistically lower mean elevations than adjacent, darker, off-swirl lanes. These topographic characteristics provide constraints on the plausible formation mechanisms for the swirls in Mare Ingenii, which in turn provide insight into lunar soil migration and evolution. We believe this correlation with topography argues for highly mobile dust transport across the lunar surface.

The visible-infrared spectra of Mercury’s surface show little variation, displaying no distinct spectral features except for the possible spectral identification of sulfide within the hollows (Vilas et al. 2016). It is essential therefore to define and map any subtle spectral heterogeneity across Mercury’s surface and to correlate these differences where possible to geomorphological features, such as impact craters, volcanic vents, and tectonic features. The Mercury Atmospheric and Surface and Composition Spectrometer (MASCS) instrument onboard MESSENGER spacecraft is the only hyperspectral reflectance spectrometer to date that has mapped Mercury’s surface in the wavelength range 320 nm - 1450 nm. The limitation of MASCS is that it’s a point spectrometer that mapped Mercury’s surface at non-uniform spatial scale. In this study, we resampled the global MASCS hyperspectral dataset to a uniform spatial resolution of 1 pixel per degree. This enabled us to perform global multivariate analyses, including standard spectral parameter maps, k-means clustering, and principal component analysis (PCA) to spectrally characterize Mercury’s surface. Among these techniques, PCA significantly improved the identification of spectral heterogeneities across Mercury correlated to both chemical and physical properties of the surface, enabling us to identify units based on grain size, the presence of amorphous materials, and space-weathering associated alterations. The global MASCS PC color-composite map derived from principal components 1, 2, and 6 effectively distinguishes varying spectro-morphologies across Mercury’s surface, highlighting the spectral properties of various geochemical terrains. We further demonstrate that PCA spectrally differentiates between the two northern volcanic plains’ geochemical regions; the high-Mg and low-Mg terrains.