Venus is the most Earth-like of the terrestrial planets, though very little is known about its surface composition. Thanks to recent advances in laboratory spectroscopy and spectral analysis techniques, this is about to change. Although the atmosphere prohibits observations of the surface with traditional imaging techniques over much of the EM spectral range, five transparent windows between ~0.86 µm and ~1.18 µm occur in the atmosphere’s CO2 spectrum. New high temperature laboratory spectra from the Planetary Spectroscopy Laboratory at DLR show that spectra in these windows are highly diagnostic for surface mineralogy [1]. The Venus Emissivity Mapper (VEM) [2] builds on these recent advances VEM is the first flight instrument specially designed to focus solely on mapping Venus’ surface using the windows around 1 µm. Operating in situ from Venus orbit, VEM will provide a global map of composition as well as redox state of the surface, enabling a comprehensive picture of surface-atmosphere interaction on Venus. VEM will return a complex data set containing surface, atmospheric, cloud, and scattering information. Total planned data volume for a typical mission scenario exceeds 1TB. Classical analysis techniques have been successfully used for VIRTIS on Venus Express [3-5] and could be employed with the VEM data. However, application of machine learning approaches to this rich dataset is vastly more efficient, as has already been confirmed with laboratory data. Binary classifiers [6] demonstrate that at current best estimate errors, basalt spectra are confidently discriminated from basaltic andesites, andesites, and rhyolite/granite. Applying the approach of self-organizing maps to the increasingly large set of laboratory measurements allows searching for additional mineralogical indicators, especially including their temperature dependence. [1] Dyar M. D. et al. 2017 LPS XLVIII, #1512. [2] Helbert, J. et al. 2016. San Diego, CA, SPIE. [3] Smrekar, S.E., et al. Science, 2010 328(5978), 605-8. [4] Helbert, J., et al., GRL, 2008 35(11). [5] Mueller, N., et al., JGR, 2008 113. [6] Dyar M. D. et al. 2017 LPS XLVIII, #3014.

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.