A5085917274- Planetary Science and Exploration
- Astro and Planetary Science
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Space Science and Extraterrestrial Life
- earthquake and tectonic studies
- Geological and Geochemical Analysis
- Space Satellite Systems and Control
- Methane Hydrates and Related Phenomena
- High-pressure geophysics and materials
- Space exploration and regulation
- Marine and environmental studies
- Spaceflight effects on biology
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Economic and Technological Innovation
- Geophysics and Gravity Measurements
- Maritime and Coastal Archaeology
- Paleontology and Stratigraphy of Fossils
- Scientific Research and Discoveries
- Defense, Military, and Policy Studies
- Science Education and Pedagogy
- Geomagnetism and Paleomagnetism Studies
- Cold Fusion and Nuclear Reactions
- Scientific Computing and Data Management
Southwest Research Institute
2016-2025
Planetary Science Institute
2021
Albion College
2021
University of Hawaiʻi at Mānoa
2021
Brown University
2021
Marshall Space Flight Center
2021
Williams & Associates
2021
University of California, Los Angeles
2021
Western University
2021
Northern Arizona University
2021
Abstract The origins of the giant planet satellites are debated, with scenarios including formation from a protoplanetary disk, sequential assembly massive rings, and recent accretion after major satellite–satellite collisions. Here, we test their predictions by simulating outer solar system bombardment calculating oldest surface ages on each moon. Our crater production model assumes projectiles originated primordial Kuiper Belt (PKB) that experienced substantial changes collisional...
Abstract Impact crater populations help us to understand solar system dynamics, planetary surface histories, and modification processes. A single previous effort standardize how data are displayed in graphs, tables, archives was a 1978 NASA report by the Crater Analysis Techniques Working Group, published 1979 Icarus . The had significant lasting effect, but later decades brought major advances statistical computer sciences while field has remained fairly stagnant. In this new work, we...
Abstract Outer solar system impact bombardment is largely unconstrained. Although recent data from the Jupiter, Saturn, and Pluto systems have produced new constraints, analysis incomplete without inclusion of Uranus system. We reanalyze crater populations with improvements in processing Voyager 2 imaging. No consensus on mid-sized Uranian satellites, Miranda, Ariel, Umbriel, Titania, Oberon, was resolved during era. For satellites available data, we find variability size–frequency...
Abstract We review the secondary‐crater research over past decade, and provide new analyses simulations that are first to model an accumulation of a combined primary‐plus‐secondary crater population as discrete cratering events. develop secondary populations by using scaling laws generate ejecta fragments, integrating trajectories individual noting location velocity at impact, estimate diameters given impact conditions. also explore relationship between impactor size–frequency distribution (...
Abstract Tropical ground ice on Mars undergoes long‐term sublimation and likely exospheric escape. Without restriction of sublimation, the cryosphere would eventually breach, leading to massive loss any underlying groundwater. We seek understand conditions under which ground‐ice seal, groundwater, subsurface habitability are preserved. Using multireservoir models for evolution deuterium‐to‐hydrogen ratios, we derive a median estimate Hesperian‐Amazonian H 2 O 60 m (interquartile range 30–120...
Abstract NASA's Mars Reconnaissance Orbiter ( MRO ) spacecraft has operated around since March 2006. The Context Camera (CTX) aboard returned >125,000 images of Mars, mostly at 5–6 m per pixel (mpp), providing ≈99% coverage with good‐quality images. Reconstruction 's orbit and camera pointing from ground tracking are offset the global coordinate system. This work focuses on correcting those data for more than 50,000 in equatorial region between ±30° latitude, which comprises 50% Mars'...
Abstract Impact crater population detection and measurement is critical to understanding solar system bodies dynamics. However, the ability detect all possible craters under different lighting camera geometries has not been systematically studied except in a few limited cases. This work presents first systematic study examining based on resolution, incidence angle, emission phase by three independent researchers also test reliability of our conclusions. We found best angles for be ∼74°–82°....
The trans-Neptunian region is observed to host a large proportion and wide variety of binary systems (components with > few tens km in size) [1, 2], offering unique opportunities for studying planetesimal formation from the protoplanetary disk subsequent evolution [3]. Since objects (TNOs) reside far Earth, observing TNOs smaller than km-scale remains challenging [4] consequently, binarity this size range unknown [5].Doublet craters are generally defined as pair adjacent, similarly-sized...
Iapetus, the outermost regular satellite of Saturn, has a drastic albedo dichotomy and an equatorial circumferential ridge that reaches heights 20 km widths 70 km. This moon is thought to have formed concurrently with so would experienced intense bombardment after its formation. The ridge, which been inferred be one most ancient features on Iapetus' surface, could reasonably expected eroded by impacts; however, it retained long continuous sections nearly pristine triangular shape slopes...
Abstract Recent dynamical modeling of the formation and evolution Saturnian satellites suggests that ages mid‐sized inner moons (Mimas, Enceladus, Tethys, Dione, Rhea) could be as young 100 Myr. This estimate is in contrast to most previous observational work suggest an age more contemporaneous with Saturn 4.5 Ga ago. Given heritage using craters constrain surface ages, we examine impact Dione imagery from NASA's Cassini ISS camera analyze their size‐frequency distributions (SFDs) understand...
This investigation was set up to study the prevalence of left ventricular hypertrophy in a hypertensive population with reference normotensive control group. From general 3498 men and women aged 35, 45, 55 65 years old were invited health examination. Participants blood pressure above 160 mmHg systolic or 95 diastolic those taking antihypertensive medication having done so during previous 6 months asked undergo an echocardiographic Normotensive controls randomly selected from same...
Abstract Current estimates place the ages of inner Saturnian satellites (Mimas, Enceladus, Tethys, Dione, and Rhea) between 4.5 Gyr 100 Myr. These are based on impact crater measurements dynamical simulations, both which have uncertainties. Models satellite evolution inherently simplified rely uncertain or unknown parameters, often difficult to verify, whereas interpretations densities depend source populations impactors, not well‐constrained in outer solar system. We investigate cratering...
Abstract Cassini mapping of Saturn’s mid‐sized icy moons well‐preserved complex craters in the 45–95 km size range provides insight into cratering processes at lower surface gravity and on targets. These are characterized by steep rim scarps, rugged hummocky floor deposits curvilinear ridges conical central peaks. Ponded impact melt or related not observed any ejecta units these craters, indicating that production may be much than predicted. Mantling drape over pre‐existing topography,...