Nadine G. Barlow

• PhD Planetary Science, UAz
• Head of Department at Northern Arizona University

Polygonal impact craters (PICs) are supposed to form as a result of impacts into structure systems within the target. The structure systems are an umbrella term which encompass faults, joints, fractures, lithographic boundaries, and other planes of weakness. These impact craters are defined as having at least two linear rim segments with a recogniz...

Martian caves are among the best locations to search for evidence of extinct/extant life, may provide access to stable water ice deposits, and offer a protected environment for human habitation. We examined the robotic exploration potential of a subset of these features. Poster URL: https://www.researchgate.net/publication/349679212_Robotic_explor...

Refer to abstract for more detailed description: https://www.researchgate.net/publication/348404184_Robotic_Exploration_Potential_of_Martian_Caves

The Dawn spacecraft revealed a heavily cratered surface of the dwarf planet Ceres. These impact craters can be used to uncover the target properties of Ceres by analyzing the morphologic and morphometric characteristics. A near-global crater database containing 44,594 craters with diameters (D) ≥ 1.0 km in the latitude range 84.66°S–89.62°N over al...

This project involved the use of a near-global Cerean crater database to identify interior morphologies and polygonal impact craters across the surface of Ceres to further understand the body's crustal characteristics. These data were acquired from the Dawn spacecraft's Framing Camera with a resolution of ~400 m/pixel.

The distribution of interior morphologies and crater morphometries provide detail into regional variations of the crustal strength of Ceres.

Based on observations with Mars Reconnaissance Orbiter images, we describe a subtle, relatively thin but continuous deposit that flows off of, and terminates well beyond (up to 5 crater radii), the layered ejecta rampart of several of the best-preserved craters on Mars.

This work is part of an ongoing study using maps of both the visible and thermophysical facies of well-preserved Martian craters to identify baseline characteristics of impact-related deposits prior to degradation. Initial mapping efforts focused on craters near the transition diameter that exhibit typically-used criteria for "fresh" craters with s...

We have conducted the first solar system-wide comparison study of central pit craters. The results of this comparative analysis combined with detailed geologic and structural mapping of well-preserved central pit craters on Mars, allow us to reconsider the proposed formation models for these pits.

Introduction: Polygonal impact craters (PICs) are non-circular craters which display at least two linear rim segments with a distinguishable angle between them. PICs can form as any regular polygon, but the most common shape observed are hexagons which display at least two to four distinct linear rim segments [1]. Previous studies show polygonal cr...

Impact crater databases are one of the first data products produced from images acquired by planetary spacecraft missions and are used in a variety of studies investigating the formation ages and geologic histories of surface units. Martian crater databases have been compiled since the first global images of the planet were acquired by the Mariner...

The Martian obliquity cycle is predominately influenced by Solar and Jovian tidal forces. The present-day axial tilt of Mars (25 degrees) is predicted to cycle between 0 degrees and 60 degrees (Mischna & Richardson 2005) with excursions up to 80 degrees(Laskar et al. 2004). We focused on Arabia Terra, a region especially well-suited for studying gl...

The Martian obliquity cycle is predominately influenced by Solar and Jovian tidal forces. The present-day axial tilt of Mars (25 degrees) is predicted to cycle between 0 degrees and 60 degrees (Mischna & Richardson 2005) with excursions up to 80 degrees(Laskar et al. 2004). We focused on Arabia Terra, a region especially well-suited for studying gl...

Introduction: Ceres is the largest body in the main asteroid belt with a radius ≈ 470 km, a mass of 9.38x10 20 kg and a surface gravity of 0.27 m/s 2 [1]. NASA's Dawn spacecraft went into orbit around Ceres on March 2015. The Framing Camera (FC) on board Dawn attained images of the Cerean surface with a resolution of approximately 400 m/pixel. Prio...

We report on the first results of a large-scale comparison study of central pit craters throughout the solar system, focused on Mars, Mercury, Ganymede, Rhea, Dione, and Tethys. We have identified 10 more central pit craters on Rhea, Dione, and Tethys than have previously been reported. We see a general trend that the median ratio of the pit to cra...

Impact craters not only provide insights into the characteristics of the crustal materials into which they excavate but also serve as repositories for materials transported by other geologic processes. They therefore can enhance our understanding of the role of both subsurface and surface volatiles throughout Martian history. Subsurface volatiles i...

Following an approach similar to that used for the Moon, Mercury's surface units were subdivided into five time-stratigraphic systems based on geologic mapping using Mariner 10 images. The absolute time scale originally suggested for the time periods associated with these systems was based on the assumption that the lunar impact-flux history applie...

Introduction: We propose a modification to the current Mars impact crater nomenclature system [1] to account for recently observed differences in crater ejecta morphology. We also present morphometric evidence to support this proposal because it is the most objective and easiest to apply as a criterion for identification of morphologic types. Most...

Here we discuss how understanding lunar bombardment can help us constrain planet formation, giant planet migration, the evolution of the asteroid and Kuiper belts, and the impact history of the Earth (with implications for the evolution of life). Whitepaper #218 submitted to the Planetary Science and Astrobiology Decadal Survey 2023-2032. Topics:...

Are are conducting a comparative study of central pit craters on Mars, icy moons, Mercury, and the Moon. Central pit craters are rare on volatile-poor bodies and have lower frequency on smaller ice-rich bodies. Some differences in pit-to-crater diameter ratio are seen on different bodies, but no consistent depth-diameter relationship is found for p...

Observations using HiRISE, CTX, and CRISM elucidating various aspects of the impact process, particularly with respect to the occurrence and emplacement of various impactites, and the structures associated with central uplifts in complex craters are summarized here.

and the MEPAG Special Regions-Science Analysis Group 2 (SR-SAG2; 26 additional committee members). 1 East Carolina University, rummelj@ecu.edu. 2 Mars Program Office, JPL/Caltech. 3 Dept. of Physics and Astronomy, Northern Arizona Univ. 4 Canadian Space Agency. Introduction: A committee of the Mars Exploration Planning and Analysis Group (MEPAG) re...

We have conducted a study of fluvial and glacial features retained within impact craters in the region of Arabia Terra, Mars between 20-40N 0-30E. We find that fluvial features are common throughout the study region but glacial features dominate north of about 30N. Crater size-frequency distribution analysis places both fluvial and glacial activity...

Two morphologic types of double-layer ejecta craters are found in the northern hemisphere of Mars. This study has investigated the geographic distribution, crater diameter dependence, preservational state, and presence/absence of radial texture for these two DLE types. Geographic distribution, particularly latitude, and diameter appear to be the pr...

Introduction: Central pit craters are a complex im-pact crater with a pit either on the crater floor (floor pits) or atop a central peak (summit pits) [1]. They encom-pass only 5% of the total crater population on Mars [2]. Formation models of central pit formation typically in-voke the presence of target volatiles, with some models proposing colla...

This study compares results of crater diameter, shape, ejecta morphologies, and interior morphologies in the northern hemisphere of Mars between older results reported from a Viking-derived crater catalog and a new crater catalog obtained from analysis of higher-resolution data sets, primarily Mars Odyssey Thermal Emission Imaging System (THEMIS) d...

A MEPAG Science Analysis Group (SAG) has undertaken an analysis of Special Regions (SR) on Mars—regions where indigenous martian life could exist or where Earth microbes, if introduced, could survive and reproduce. The SR-SAG has considered the impact of SR on future human activities on the martian surface. Human exploration requires access to in-s...

A committee of the Mars Exploration Program Analysis Group (MEPAG) has reviewed and updated the description of Special Regions on Mars as places where terrestrial organisms might replicate (per the COSPAR Planetary Protection Policy). This review and update was conducted by an international team (SR-SAG2) drawn from both the biological science and...

Low-Aspect-Ratio Layered Ejecta (LARLE) craters are a unique landform found on Mars. LARLE craters are characterized by a crater and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which terminates in a sinuous, almost flame-like morphology. We have conducted a survey to identify all LARLE craters ⩾1-km-diameter with...

DefinitionCrater rays are filamentous deposits occurring radial or subradial to impact craters. They exhibit an albedo different from their surroundings in visible and/or infrared wavelengths.Synonyms(Lunar) bright rays; (Lunar) rays; Ray system; Thermal raysDescriptionRays are long, narrow, generally high albedo (bright) approximately linear depos...

This report represents the work of a committee sponsored by the Mars Exploration Planning and Analysis Group (MEPAG) to review and update the technical information that under-lies the interpretation of planetary protection Special Regions on Mars as designated in the COSPAR Planetary Protection Policy. This review and update was conducted with the...

This report represents the work of a committee sponsored by the Mars Exploration Planning and Analysis Group (MEPAG) to review and update the technical information that under-lies the interpretation of planetary protection Special Regions on Mars as designated in the COSPAR Planetary Protection Policy. This review and update was conducted with the...

DefinitionImpact crater ejecta morphology displaying two continuous deposits.CategoryA type of layered ejectaSynonymsDLE; Double lobe ejecta; Pedestal crater (Ganymede)Description/Structural UnitsDouble-layer ejecta (DLE) craters have been identified on Mars and Ganymede. The inner layer of the DLE morphology is thicker and terminates in a concave...

DefinitionImpact ejecta is material excavated from a crater cavity during impact; most ejecta (when ejecta velocity is less than escape velocity) will form a deposit, or layer, of debris surrounding the crater cavity, thinning with distance.SynonymsEjecta blanket; Ejectamenta (Obsolete)DescriptionEjecta is comprised of target materials excavated du...

Introduction: Arabia Terra is the largest expanse of ancient highlands material north of the Martian equator. Crater size-frequency distribution analysis indicates the region formed during the Noachian and has been exposed to various geologic processes since that time. Orbiters and the Opportunity rover provide abundant evidence that long-lived sub...

Introduction: The Moon is a standard of compari-son for rates and styles of impact cratering in our Solar System. Its surface preserves cratering events that span both ancient highland and younger maria terrains. This study utilized Lunar Reconnaisssance Orbiter (LRO) data to investigate the characteristics and distributions of central peak, wall t...

This project characterizes lunar impact crater morphology on the eastern nearside through use of new Lunar Reconnaissance Orbiter imagery and GIS analysis.

DefinitionImpact crater ejecta pattern which displays a layered ejecta morphology close to the crater rim and secondary crater chains beyond the edge of the layered ejecta deposit.CategoryA type of ejecta, containing both layered ejecta and radial ejecta.SynonymsDiverse ejecta; MLERSRd; Radial-lobate ejecta; SLERSRd; Transitional ejectaDescriptionT...

An unusual crater morphology is found primarily at high latitudes on Mars. These craters display an extensive outer deposit beyond the normal layered ejecta blanket. This outer deposit extends up to 20 crater radii from the rim, terminates in a sinuous flame-like edge, and is extremely thin, leading to a low aspect ratio (A = thickness/length). The...

Martian Low-Aspect-Ratio Layered Ejecta (LARLE) craters are characterized by a extensive but thin layer extending beyond the normal layered ejecta blankets. We propose that base surge is responsible for producing the LARLE layer.

Characteristics of martian central pit craters provide constraints on the possible formation mechanism for these features on other solar system bodies.

We propose that the extensive ejecta layer of LARLE craters is a base surge deposit that incorporates secondary ejecta from fine-grained mantles.

We have investigated the role of terrain on depth-diameter and simple-complex transition diameter of martian impact craters in four regions of the planet.

We have completed a survey of all LARLE craters within the ±75 latitude zone on Mars. Lobateness and ejecta mobility values support a base surge formation.

We are using crater morphologies to investigate the role of surficial and subsurface volatiles in the evolution of the ancient Arabia Terra region of Mars.

We are compiling a database of all lunar craters 5 km in diameter and larger. We present results for the western equatorial nearside region.

We report on the construction of the Catalog of Large Lunar Impact Craters (diameters >5 km), which here focuses on the north and south polar regions.

The four terrestrial planets (Mercury, Venus, Earth, and Mars) and Earth's Moon display similar compositions, interior structures, and geologic histories. The terrestrial planets formed by accretion ˜ 4.5 Ga ago out of the solar nebula, whereas the Moon formed through accretion of material ejected off Earth during a giant impact event shortly after...

Reanalysis of the results from the Viking Landers by Navarro-­‐Gonzales et al in 2010 suggested detection of organic carbon in the soil at both VL1 and VL2 sites at the level of a few ppm. By using a numerical radiative transfer code for the Martian atmosphere, we will show how this level of carbon can be explained if the source of the organic carb...

We are using primarily Lunar Reconnaissance Orbiter (LRO) information to compile a new global database of lunar impact craters 5 km in diameter and larger. Each crater’s information includes coordinates of the crater center (ULCN 2005), crater diameter (major and minor diameters if crater is elliptical), azimuthal angle of orientation if crater is...

doi:10.1029/2011JE004023 A UV photolytic process was studied for the production of methane from carbonaceous chondrites under simulated martian conditions. Methane evolution rates from carbonaceous chondrites were found to be positively correlated to temperature (‒80 to 20 oC) and the concentration of carbon in the chondrites (0.2 to 1.69 wt%); and...

The Arabia Terra region contains evidence of the long-term influence of both surficial and subsurface volatiles. This study is using impact crater morphologies and morphometries to investigate the role of H2O on the geologic evolution of Arabia.