74 research outputs found
LineaMapper: A deep learning-powered tool for mapping linear surface features on Europa
No full textAs discontinuities of the smooth icy surface, linear surface features might be directly or indirectly linked to Europa’s subsurface ocean. Mapping and categorising Europa’s lineaments is a means of retrieving information that could be linked to their formation history. As of today, planetary mapping is mainly conducted manually, which is tedious and subject to human bias once data sets become large. Mapping is further complicated by the heterogeneous quality and coverage of the available image data.
Here, we train LineaMapper, a convolutional neural network (Mask R-CNN), to conduct instance segmentation of the four main units of linear surface features on Europa: bands, double ridges, ridge complexes and undifferentiated lineae. LineaMapper is trained on the basis of 15 mosaics from the Galileo solid-state imager data, yielding 930 training tiles. With LineaMapper, we provide a new method that facilitates detailed mapping of lineaments in Galileo images. LineaMapper could be applied to data to be returned by the Europa Imaging System (EIS) onboard the Europa Clipper mission. We validate LineaMapper v1.0 on an independent test set. On this test set, LineaMapper shows an overall higher precision than recall. In other words, there are more non-detections of actual lineaments than there are false detections of lineaments. The model shows the most correct predictions for double ridges (highest precision), while the most complete detections happen for ridge complexes (highest recall), compared with the ground truth. In some cases, LineaMapper preserves the cross-cutting relationships. The biggest strength of LineaMapper lies in its speed and tunable output. In the future, LineaMapper can be retrained, fine tuned and applied to similar looking features, for example wrinkle ridges on Venus, ridges on other planets and moons or even dust devil tracks on Mars
Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon
No full textIn a database of lunar fractured boulders (Rüsch & Bickel, 2023, https://doi.org/10.3847/psj/acd1ef), we found boulders with reflectance features dissimilar to previously known morphologies. We performed a photo-geologic investigation and determined that the features correspond to a dust mantling on top of boulders with a unique photometric behavior. We next performed a photometric model inversion on the dust mantling using Bayesian inference sampling. Modeling indicates that the dust photometric anomaly is most likely due to a reduced opposition effect, whereas the single scattering albedo is not significantly different from that of the nearby background regolith. This implies a different structure of the dust mantling relative to the normal regolith. We identified and discussed several potential processes to explain the development of such soil. None of these mechanisms can entirely explain the multitude of observational constraints unless evoking anomalous boulder properties. Further study of these boulders can shed light on the workings of a natural dust sorting process potentially involving dust dynamics, a magnetic field, and electrostatic dust transport. The presence of these boulders appears to be limited to the Reiner K crater near the Reiner Gamma magnetic and photometric anomaly. This close spatial relationship further highlights that poorly understood processes occur in this specific region of the Moon
Hoe God aanwezig is in het werk van Maarten ’t Hart
No full textMaarten ’t Hart is widely regarded as the prototypical Dutch author who has left his Orthodox Reformed background behind. Yet religion is present throughout his work. In her dissertation Religion im Werk von Maarten ’t Hart (2022), German theologian Christina Bickel describes the playful manners in which ’t Hart deals with religion as an inspiring way to open the mind of modern man to transcedental reflections. Her interdisciplinary approach combining literary analysis, theological hermeneutics and homiletics, offers a surprising example of the reception of a Dutch author within a foreign cultural context.Maarten ’t Hart is widely regarded as the prototypical Dutch author who has left his Orthodox Reformed background behind. Yet religion is present throughout his work. In her dissertation Religion im Werk von Maarten ’t Hart (2022), German theologian Christina Bickel describes the playful manners in which ’t Hart deals with religion as an inspiring way to open the mind of modern man to transcedental reflections. Her interdisciplinary approach combining literary analysis, theological hermeneutics and homiletics, offers a surprising example of the reception of a Dutch author within a foreign cultural context.Maarten ’t Hart is widely regarded as the prototypical Dutch author who has left his Orthodox Reformed background behind. Yet religion is present throughout his work. In her dissertation Religion im Werk von Maarten ’t Hart (2022), German theologian Christina Bickel describes the playful manners in which ’t Hart deals with religion as an inspiring way to open the mind of modern man to transcedental reflections. Her interdisciplinary approach combining literary analysis, theological hermeneutics and homiletics, offers a surprising example of the reception of a Dutch author within a foreign cultural context
Automated Discovery of Anomalous Features in Ultralarge Planetary Remote-Sensing Datasets Using Variational Autoencoders
No full textThe NASA Lunar Reconnaissance Orbiter (LRO) has returned petabytes of lunar high spatial resolution surface imagery over the past decade, impractical for humans to fully review manually. Here, we develop an automated method using a deep generative visual model that rapidly retrieves scientifically interesting examples of LRO surface imagery representing the first planetary image anomaly detector. We give quantitative experimental evidence that our method preferentially retrieves anomalous samples such as notable geological features and known human landing and spacecraft crash sites. Our method addresses a major capability gap in planetary science and presents a novel way to unlock insights hidden in ever-increasing remote-sensing data archives, with numerous applications to other science domains
Automated astronaut traverses with minimum metabolic workload: Accessing permanently shadowed regions near the lunar South pole
No full textAltres ajuts: acords transformatius de la UABThe Artemis exploration zone is a topographically complex impact-cratered terrain. Steep undulating slopes pose a challenge for walking extravehicular activities (EVAs) anticipated for the Artemis III and subsequent missions. Using 5 m/pixel Lunar Orbiter Laser Altimeter (LOLA) measurements of the surface, an automated Python pipeline was developed to calculate traverse paths that minimize metabolic workload. The tool combines a Monte Carlo method with a minimum-cost path algorithm that assesses cumulative slope over distances between a lander and stations, as well as between stations. To illustrate the functionality of the tool, optimized paths to permanently shadowed regions (PSRs) are calculated around potential landing sites 001, nearby location 001(6), and 004, all within the Artemis III 'Connecting Ridge' candidate landing region. We identified 521 PSRs and computed (1) traverse paths to accessible PSRs within 2 km of the landing sites, and (2) optimized descents from host crater rims into each PSR. Slopes are limited to 15° and previously identified boulders are avoided. Surface temperature, astronaut body illumination, regolith bearing capacity, and astronaut-to-lander direct view are simultaneously evaluated. Travel times are estimated using Apollo 12 and 14 walking EVA data. A total of 20 and 19 PSRs are accessible from sites 001 and 001(6), respectively, four of which maintain slopes <10°. Site 004 provides access to 11 PSRs, albeit with higher EVA workloads. From the crater rims, 94 % of PSRs can be accessed. All round-trip traverses from potential landing sites can be performed in under 2 h with a constant walk. Traverses and descents to PSRs are compiled in an atlas to support Artemis mission planning
Directing the immune response: T cells, T cell receptors and T cell receptor mimics
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The hermetic logos : reading the "Corpus Hermeticum" as a reflection of Graeco-Egyptian mentality
No full textThis study analyses Hermetic literature and focuses on the seventeen treatises of the so-called Corpus Hermeticum. It takes as its starting point the assumption that what are nowadays known as the Philosophical Hermetica emerged as a product of a Graeco-Egyptian process of self-perception. As will be demonstrated, Hermetic literature helps our understanding of how reformulations of symbolic universes led to a specific Graeco-Egyptian mentality. The Hermetica will be treated as the result of cross-cultural exchange between Greek and Egyptian symbolic universes. Hermetic literature will therefore be analysed according to its historical context, i.e. as part of a Greek-Egyptian dialogue
Global Mapping of Fragmented Rocks on the Moon with a Neural Network: Implications for the Failure Mode of Rocks on Airless Surfaces
No full textISSN:2632-333
The Distribution and Accessibility of Geologic Targets near the Lunar South Pole and Candidate Artemis Landing Sites
No full textISSN:2632-333
Sequential confidence bands for densities
No full textWe propose a fully sequential procedure for constructing a fixed width confidence band for an unknown density on a finite interval and show the procedure has the desired coverage probability asymptotically as the width of the band approaches zero. The procedure is based on a result of Bickel and Rosenblatt (1973, Ann. Statist. 1, 1071-1095). Its implementation in the sequential setting cannot be obtained using Anscombe's theorem, because the normalized maximal deviations between the kernel estimate and the true density are not uniformly continuous in probability (u.c.i.p.). Instead, we obtain a slightly weaker version of the u.c.i.p. property and a correspondingly stronger convergence property of the stopping rule. These together yield the desired results. We also present some simulation results and applications of the basic method to stopping rules of interest. Similar result is also obtained for censored data case.Made available in DSpace on 2011-05-07T14:00:30Z (GMT). No. of bitstreams: 2
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