Visible and near infrared spectroscopy of Mercury and Venus from orbit

Abstract The present thesis exposes methods and results obtained exploiting information provided by visible and near-infrared spectra over Mercury and Venus. We use information from different datasets to perform a geologically supervised investigation, in order to identify the presence of compositional heterogeneities and reconstruct the stratigraphy in the shallow crust of the two Terrestrial planets. We name these procedures “Datasets Fusion Techniques” (DFTs). We combine the MASCS dataset with the MDIS dataset from the MESSENGER mission to analyze the local and global crustal properties of Mercury. We select all MASCS observations contained within geologic units previously mapped using high-resolution MDIS NAC images. Similarly, we combine the Venus Express VIRTIS dataset with Magellan SAR imaging dataset for identifying location and extent of the recently active lava flows possibly responsible for the relatively high 1 μm emissivity anomalies observed by the VIRTIS instrument on Idunn Mons on Venus. Using a forward modeling-like procedure, we mapped a number of lava flows on Magellan SAR images, then assigning them a different value of simulated emissivity at each iteration. We found one non-unique solution which well approximates VIRTIS observations. This thesis is a comprehensive study which embraces three main research works performed during the current PhD project. The results show the occurrence of vertical and horizontal heterogeneities in the composition of the shallow crust of Mercury, providing as well important indications for the presence of N-S dichotomy. We also found that the recently active lava flows on Idunn Mons are most likely flank flows located on the eastern flank of the volcanic structure. We could finally reconstruct the stratigraphy beneath the local scale study areas of Mercury and Venus. This PhD thesis demonstrates that DFTs can be used as a powerful expedient for improving the quality of information we can achieve from remote sensing analyses.Original papers Piero D’Incecco, Jörn Helbert, Mario D’Amore, Alessandro Maturilli, James W. Head, Rachel L. Klima, Noam R. Izenberg, William E. McClintock, Harald Hiesinger, Sabrina Ferrari, Shallow crustal composition of Mercury as revealed by spectral properties and geological units of two impact craters, Planetary and Space Science, Volume 119, 15 December 2015, Pages 250-263, ISSN 0032-0633, http://dx.doi.org/10.1016/j.pss.2015.10.007. (http://www.sciencedirect.com/science/article/pii/S0032063315003062) Keywords: Mercury; MESSENGER; MASCS; MDIS; Impact craters; Stratigraphy Piero D’Incecco, Jörn Helbert, Mario D’Amore, Sabrina Ferrari, James W. Head, Alessandro Maturilli, Harald Hiesinger, A geologically supervised spectral analysis of 121 globally distributed impact craters as a tool for identifying vertical and horizontal heterogeneities in the composition of the shallow crust of Mercury, Planetary and Space Science, Volume 132, 1 November 2016, Pages 32-56, ISSN 0032-0633, http://dx.doi.org/10.1016/j.pss.2016.08.004. (http://www.sciencedirect.com/science/article/pii/S0032063315301094) Keywords: Mercury; MESSENGER; MASCS; MDIS; Impact craters; Datasets Fusion Techniques (DFTs) Piero D'Incecco, Nils Müller, Jörn Helbert, Mario D'Amore, Idunn Mons on Venus: Location and extent of recently active lava flows, Planetary and Space Science, Volume 136, February 2017, Pages 25-33, ISSN 0032-0633, http://dx.doi.org/10.1016/j.pss.2016.12.002. (http://www.sciencedirect.com/science/article/pii/S003206331630112X) Keywords: Venus; VIRTIS; Magellan; Volcanism; Idunn Mons; Stratigraph

Geology of the Imdr Regio area of Venus

ABSTRACTWe present a 1:5,000,000 geological map of the Imdr Regio area of Venus. Geological mapping was conducted using synthetic aperture radar (SAR) images, altimetry and stereo-derived topography data from NASA's Magellan mission. The map covers an area of approximately 7.9 × 106 km2 and exhibits a variety of tectonic structures and units of volcanic origin related to the evolution of Imdr Regio and surrounding plains. We have differentiated primary structures related to the emplacement of the different units from tectonic structures that deform them. These structures are also organized between those that are regional in extent and those that are related to the evolution of local large tectono-volcanic structures. The units in the map area represent different geologic processes (e.g. volcanism) that took place during the evolution of the large topographic rise. Geologic mapping illustrates a complex evolution with different styles of deformation and volcanism in this part of the planet