Impact of environmental, instrumental and data processing parameters on the performance of the Radar for Icy Moon Exploration

Il radar sounding è una tecnica molto promettente per la ricerca di ambienti abitabili sulle lune ghiacciate di Giove, poiché permetterà di osservare direttamente sotto la superficie fino a profondità di diversi chilometri. In questo lavoro si è seguita una metodologia basata sull'utilizzo di dati raccolti su terreni analoghi di altri corpi del sistema solare, per valutare l'impatto di alcuni parametri fondamentali sulle prestazioni di RIME (Radar for Icy Moon Exploration)

Five decades of radioglaciology

Radar sounding is a powerful geophysical approach for characterizing the subsurface conditions of terrestrial and planetary ice masses at local to global scales. As a result, a wide array of orbital, airborne, ground-based, and in situ instruments, platforms and data analysis approaches for radioglaciology have been developed, applied or proposed. Terrestrially, airborne radar sounding has been used in glaciology to observe ice thickness, basal topography and englacial layers for five decades. More recently, radar sounding data have also been exploited to estimate the extent and configuration of subglacial water, the geometry of subglacial bedforms and the subglacial and englacial thermal states of ice sheets. Planetary radar sounders have observed, or are planned to observe, the subsurfaces and near-surfaces of Mars, Earth's Moon, comets and the icy moons of Jupiter. In this review paper, and the thematic issue of the Annals of Glaciology on ‘Five decades of radioglaciology’ to which it belongs, we present recent advances in the fields of radar systems, missions, signal processing, data analysis, modeling and scientific interpretation. Our review presents progress in these fields since the last radio-glaciological Annals of Glaciology issue of 2014, the context of their history and future prospects

Subsurface Mapping of Deserts and Polar Regions Using Radar Data on Earth and Mars

There are abundant resources buried underground that are difficult to be investigated remotely. This thesis is concerned with the development and utility of various novel processing methods for different radar instruments in the field of subsurface mapping on Earth and Mars. Firstly, advanced Synthetic Aperture Radar (SAR) imaging and Interferometric SAR (InSAR) techniques are applied to assess their potential for revealing subsurface features in the eastern Sahara Desert. The radar penetration depth at L-band (1.25 GHz) is estimated to be 1-2 m over paleochannels in the Sahara Desert, given an initial assumption that radar penetration occurs in the sand accumulation areas. The L-band frequency of previous and existing spaceborne SAR mission is shown to limit the penetration depth to a few metres below the surface. However, over the terrestrial ice-sheets, a radar instrument, the Multi-Coherent Radar Depth Sounder (MCoRDS) from the NASA Operation Ice Bridge (OIB) mission, can penetrate the ice sheet down to 3 km, revealing extensive englacial layers. An automated layer tracing method based on the Continuous Wavelet Transform (CWT) and Hough Transform (HT) is proposed to detect and digitise these englacial layers in Greenland. The results show that this proposed method can restore at least 72% of the isochrones when compared with previous results. Given the research interests of the department and inspired by the similarity of the layering phenomenon between the Earth and Martian polar regions, the layer tracing method is adjusted and applied to SHAllow RADar (SHARAD) radargrams from the Mars Reconnaissance Orbiter. This method is demonstrated on the SHARAD data in Promethei Lingula as this 6 is the only region with coherent subsurface echo returns near the south pole, resulting in the extraction of six distinct subsurface interfaces, which record past depositional and erosional history and may be associated with past climate change on Mars

Probabilistic graphical techniques for automated ice-bottom tracking and comparison between state-of-the-art solutions

We present improvements to existing frameworks for automated extraction of ice interfaces applied to two-dimensional and three-dimensional radar echograms of polar ice sheets. These improvements consist of novel image pre-processing steps and empirically-derived cost functions that allow for the integration of further domain-specific knowledge into the models employed. Along with an explanation of our modifications, we demonstrate the results obtained by our proposed models and algorithms, such as a 43% decrease in mean tracking error in the case of three-dimensional imagery. We also present the results obtained by several state-of-the-art ice-interface tracking solutions, and compare all automated results with manually-corrected ground-truth data. Furthermore, we perform a self-assessment of tracking results by analyzing the differences found between the automatically extracted ice-layers in cases where two separate radar measurements have been made at the same location

The Sixth International Conference on Mars Polar Science and Exploration : September 5-9, 2016, Reykjavik, Iceland

The conference is designed to pull together the current state of Mars polar research from many fields, including geology, atmospheric, and climate sciences.European Geophysical Union Icelandic Meteorological Office International Association of Cryospheric Sciences Lunar and Planetary Institute (LPI) NASA Mars Program Office Planetary Science Institute Southwest Research Institute Université de Nantes University of Iceland in ReykjavikConference Organizing Committee, Isaac Smith, Convener, Southwest Research Institute [and 7 others] ; Science Organizing Committee, Wendy Calvin, University of Nevada [and 13 others

9th Annual Jackson School of Geosciences Student Research Symposium, February 15, 2020

ConocoPhillipsGeological Science

Martian Araneiforms: A Review

Araneiforms are enigmatic dendritic negative topography features native to Mars. Found across a variety of substrates and exhibiting a range of scales, morphologies, and activity level, they are hypothesized to form via insolation-induced basal sublimation of seasonal CO2 ice. With no direct Earth analog, araneiforms are an example of how our understanding of extant surface features can evolve through a multipronged approach using high resolution change-detection imaging, conceptual and numerical modeling, and analog laboratory work. This review offers a primer on the current state of knowledge of Martian araneiforms. We outline the development of their driving conceptual hypothesis and the various methodologies used to study their formation. We furthermore present open questions and identify future laboratory and modeling work and mission objectives that may address these questions. Finally, this review highlights how the study of araneiforms may be used as a proxy for local conditions and perhaps even past seasonal dynamics on Mars. We also reflect on the lessons learnt from studying them and opportunities for comparative planetology that can be harnessed in understanding unusual features on icy worlds that have no Earth analog

Comparative study of the diachronic evolution of the geological and volcanological environments of the Earth and the Saturnian satellites, Titan and Enceladus

Η παρούσα διδακτορική διατριβή αφορά τη μελέτη των περιβαλλόντων του Τιτάνα και του Εγκέλαδου, δορυφόρων του Κρόνου, μέσω της ανάλυσης δεδομένων που ανακτήθηκαν από τη διαστημική αποστολή Cassini-Huygens. Αρχικά παρουσιάζεται η επισκόπηση της γεωλογίας του Τιτάνα, με επίκεντρο τις γεωλογικές δομές και διεργασίες και το συσχετισμό μεταξύ της ατμόσφαιρας, της επιφάνειας και του εσωτερικού του δορυφόρου. Οι μορφοτεκτονικές δομές κατατάσσονται σε συγκεκριμένες κατηγορίες βάσει γήινων μοντέλων σχηματισμού. Επιφανειακές περιοχές του Τιτάνα, οι οποίες θεωρούνται συνδεδεμένες με το εσωτερικό, συγκρίθηκαν με γεωφυσικά μοντέλα παλιρροιακής στρέβλωσης και διαπιστώθηκε ότι συμπίπτουν σε σχέση με τη θέση, την επιφάνεια και την εσωτερική ενεργότητα. Ένα δεύτερο μέρος της διδακτορικής διατριβής παρουσιάζει την ενδελεχή ανάλυση συγκεκριμένων περιοχών του Τιτάνα –όπως αυτές καθορίζονται μέσω μιας στατιστικής μεθόδου– με επίκεντρο την επιφανειακή ανακλαστικότητα που παρουσιάζουν και τη χημική σύνθεση από την επεξεργασία δεδομένων του φασματογράφου Cassini/VIMS (εγγύς υπέρυθρη περιοχή του φάσματος από 0,4 έως 5 micron). Η εφαρμογή ενός εκσυγχρονισμένου και state-of-the-art κώδικα μεταφοράς ακτινοβολίας, επέδειξε τη φασματική συμπεριφορά και το εύρος της φωτεινότητας αυτών των περιοχών. Η έρευνα τριών σημαντικών περιοχών, που έχουν προταθεί ως υποψήφιες κρυοηφαιστειακές (Hotei Regio, Tui Regio και Sotra Patera), παρουσίασε ενδείξεις χρονικής μεταβολής της επιφανειακής ανακλαστικότητας για δύο από αυτές σε μια χρονική περίοδο από 1-3,5 χρόνια, υποδεικνύοντας δυναμικές εξωγενείς - ενδογενείς διεργασίες, οι οποίες επηρεάζουν την επιφάνεια και είναι συμβατές με φαινόμενα κρυοηφαιστεότητας στην περίπτωση της Sotra Patera. Επίσης, οι διαδικασίες που σχηματίζουν την επιφάνεια του Εγκέλαδου περιγράφονται λεπτομερειακά στη διατριβή. Σε ένα τρίτο μέρος, γήινα ανάλογα επιφανειακών εμφανίσεων καθώς και διεργασιών παρουσιάζονται εκτεταμένα, επισημαίνοντας ενδιαφέρουσες ομοιότητες και διαφορές μεταξύ της πυριτικής Γης και των παγωμένων δορυφόρων. Οι αστροβιολογικές συσχετίσεις αυτής της εργασίας διεξάγονται στο πλαίσιο της αναζήτησης περιβαλλόντων κατοικησιμότητας στο εξωτερικό ηλιακό σύστημα. Όλες οι προαναφερθείσες μελέτες συνδέονται με την προετοιμα σία των μελλοντικών διαστημικών αποστολών και των οργάνων τους στα συστήματα του Κρόνου και του Δία. Τέλος, συζητούνται οι δυνατότητες εκλαΐκευσης της επιστήμης και οι προοπτικές που παρουσιάζει η συγκεκριμένη έρευνα.This thesis presents on the study of the environment of Titan and Enceladus, Saturn’s satellites observed by the Cassini-Huygens mission. Various aspects of the geology of Titan are presented focusing on the characteristics of the surface geological features and processes,the internal structure and the correlation with the atmosphere. The morphotectonic features are presented on the basis of terrestrial models. Moreover, Titan areas probably correlated with the interior are tested against a geophysical model of tidal distortion and found to conform with localisation and internal dynamics. We then study the surface albedo and composition of specific Titan areas (Hotei Regio, Tui Regio, Sotra Patera) –determined by the PCA method- based on data from Cassini/VIMS (0.4–5 μm) on which a radiative transfer code is applied with the most updated spectroscopic parameters. Monitoring of these areas showed surface albedo changes in the course of 1-3.5 yrs, implying dynamic exogenic-endogenic processes that affect the surface and compatible with cryovolcanism in the case of Sotra Patera. Processes that form the surface of Enceladus are also discussed. In addition, the analogies with the Earth's surface and possible internal processes on the icy satellites are being explored. The astrobiological implications of this work are discussed within the framework of the quest for habitable environments in our outer Solar system. These studies are related to the preparation of future space missions to the systems of Jupiter and Saturn and payload capability. Finally, public awareness and perspectives of this research are discussed

Significant achievements in the planetary geology program, 1981

Recent developments in planetology research are summarized. Important developments are summarized in topics ranging from solar system evolution, comparative planetology, and geologic processes, to techniques and instrument development for future exploration