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NASA NTRSDate not supplied

Determining the Importance of In-Flight Treadmill Running Capabilities for Maintaining Astronaut Health and Performance

BACKGROUND: Physical deconditioning induced via spaceflight is most effectively attenuated through in-flight exercise training. Throughout its evolution, NASA has implemented advancements to in-flight exercise countermeasures, culminating in the triad of devices currently used aboard the International Space Station (ISS): a treadmill (T2), cycle ergometer (CEVIS), and resistance exercise device (ARED). Despite high-quality exercise devices and prescriptions, many crewmembers experience reductions in both aerobic capacity (VO2peak pre-post mean change: -10%) and strength (knee isokinetic pre-post mean change: -15%). As NASA moves towards exploration missions, which will impose greater size, power, and time constraints on exercise systems in addition to physically demanding surface extravehicular activities (EVAs), providing robust capabilities to protect crew health and performance should be prioritized. OVERVIEW: Future missions to the Lunar and Martian surfaces will include EVAs requiring ambulation and greater physical exertion than those in Apollo missions. While the exercise device concepts planned for exploration missions include resistive and aerobic capabilities, they do not allow for ambulation. Specifically, the countermeasure planned for Artemis Lunar transit is a flywheel device, which provides both exercise modalities through a single resistive cable. While more robust than the flywheel, the devices planned for the Lunar orbital space station, and subsequent Mars habitats, will provide distinct aerobic and resistance modalities capable of achieving high intensities. However, these modalities do not include a treadmill. Recent research suggests that greater in-flight running intensity and volume attenuate decrements in aerobic capacity and strength; however, this has not been experimentally confirmed. The Exploration Exercise Treadmill Requirements study is currently underway, aiming to determine the effects of exercising without a treadmill on aerobic capacity, strength, bone density, and sensorimotor function during long-duration spaceflight. DISCUSSION: Providing running capabilities on future exploration missions may help to maintain astronaut physical ability, reduce injury, and promote health. Studies quantifying the effects of using exploration exercise devices are in progress, which will help provide critical recommendations on whether a treadmill is a necessary component of the in-flight training regime. This presentation will discuss the capabilities of exploration exercise devices and the potential implications of not having running capabilities during long-duration spaceflight.

Alyssa N Varanoske↗
NASA NTRSDate not supplied

Gravity Sag Test Tower

Gravity sag is the effect on optical surfaces due to gravity. Additionally, optics manufactured in a gravitational field are made with inherent stresses built in. When these optics are flown in space those stresses release. We call this effect gravity release or “G-release”. To characterize the 0-G shape of optics, theory provides two methods: n-rotation test and face-up/face-down test.

Stephen Cheney↗
DOE OSTI2015

Photonic crystal scintillators and methods of manufacture

Photonic crystal scintillators and their methods of manufacture are provided. Exemplary methods of manufacture include using a highly-ordered porous anodic alumina membrane as a pattern transfer mask for either the etching of underlying material or for the deposition of additional material onto the surface of a scintillator. Exemplary detectors utilizing such photonic crystal scintillators are also provided.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Mercury removal sorbents

Sorbents and methods of using them for removing mercury from flue gases over a wide range of temperatures are disclosed. Sorbent materials of this invention comprise oxy- or hydroxyl-halogen (chlorides and bromides) of manganese, copper and calcium as the active phase for Hg.sup.0 oxidation, and are dispersed on a high surface porous supports. In addition to the powder activated carbons (PACs), this support material can be comprised of commercial ceramic supports such as silica (SiO.sub.2), alumina (Al.sub.2O.sub.3), zeolites and clays. The support material may also comprise of oxides of various metals such as iron, manganese, and calcium. The non-carbon sorbents of the invention can be easily injected into the flue gas and recovered in the Particulate Control Device (PCD) along with the fly ash without altering the properties of the by-product fly ash enabling its use as a cement additive. Sorbent materials of this invention effectively remove both elemental and oxidized forms of mercury from flue gases and can be used at elevated temperatures. The sorbent combines an oxidation catalyst and a sorbent in the same particle to both oxidize the mercury and then immobilize it.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Development of an Electrochemical Impedance Instrument for Monitoring Corrosion Formation (Oxide and Hydride) on Cladding Materials

The objective of this work package is to develop electrochemical impedance spectroscopic (EIS) techniques for the in pile measurement of changes in cladding materials in coupling with model simulation and material characterization. This work package will involve the initial development of electrochemical sensing technologies for measuring spatial and time resolved changes in cladding chemistry. Specific attention will be paid to monitoring changes in monitor cladding corrosion including oxide and hydride formation and deformation. The planned work during this period was focused on cladding material zirconium alloy corrosion, oxide and hydride development, and to characterize samples using EIS under controlled gas atmosphere, atom probe tomography (APT), Raman Spectroscopy, and Synchrotron X-ray diffraction (XRD). The corrosion, including oxide and hydride of zirconium alloy samples, was tested in this study. The samples were treated at a gas environment containing 3% H2 (vol%) balanced with N2 gas at various temperatures (100 – 500°C) and different times (up to 60 hours) and were characterized by in situ EIS. After treatment, various characterization techniques were applied to measure the samples, including TGA, Ramen, XRD, and APT. This study found that impedance spectra can be affected significantly with (furnace/environment) temperature. Higher temperature resulted in higher overall impedance, and longer exposure time exerted similar effects. Proof of concept characterization of oxidized samples, including TGA, Raman, XRD, and APT, were accomplished on samples exposed to 700 oC gas environment containing 20% O2 and 80% N2. TGA provides observable breakaway and bulk oxide growth measurements. High-temperature, in-situ Raman provides observation of oxidation stress at the surface of the oxide. Additionally, a transition from tetragonal to monoclinic zirconia can be seen early in the oxidation experiment. Specifically, tetragonal-rich zirconia is seen at the metal/oxide interface, where a transition to monoclinic-rich zirconia is seen in the bulk of the oxide. It has also been confirmed that highly compressive residual stresses are seen near the metal/oxide interface. It is concluded that the transition from tetragonal to monoclinic zirconia is induced by massive shifts in stress as the oxide grows. APT has supplied evident differences in the distribution of zirconium and oxygen at the metal/oxide interface. On the pre-breakaway sample, the metastable Zr(O) region at the boundary is relatively thin, interfaced by Zr-rich (i.e., metal) and O-rich (i.e., ZrO2) on either side. In contrast, it has been seen on a post-breakaway sample that the Zr(O) metastable region is much greater in thickness, with evidence of four “zones” showing slightly contrasting composition between 49-54% Zr. In addition, it can be seen from the Zr-2.65Nb post-breakaway sample that secondary element concentrations are considerably different than bulk composition measurements show. Specifically, Nb concentration is much lower than expected, whereas Fe concentration is much higher than expected. These differences could play a role in each element’s contribution to oxide growth mechanisms, as well as causation for breakaway. Future work is focused on analyzing EIS spectra of hydride and its correlation with characterization features, finite element (FE) modeling of cladding materials, electrochemical sensor development, targeting cladding oxides/hydrides under thermodynamic equilibria, during transients and under irradiation.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Transient Unsaturated Zone Modeling of Radioactive Waste Pits at Los Alamos National Laboratory - 87544 - 18432

Waste disposals at Material Disposal Area G (MDA G) at Los Alamos National Laboratory (LANL) occur primarily in a series of long, rectangular pits into which layers of waste have been emplaced beginning in the late 1950's. MDA G is situated in north-central New Mexico on top of Mesita del Buey, a narrow 3 km long mesa in the Parajito Plateau. The mesa is composed primarily of volcanic tuff from two principle volcanic eruptions in the Jemez Mountains which deposited the Otowi and Tshirege Members of the Bandelier Tuff. The Cerros del Rio Basalt underlay the tuff units and extends down for approximately 200 meters. The water table lies within the basalts at around 300 m below the surface of the mesa. The local climate is temperate and semiarid, averaging around 34 cm of precipitation per year. Ambient subsurface moisture conditions are dry, with water content typically below 10%. During disposal operations, open pits are subject to enhanced infiltration compared to the final covered configuration due to the unvegetated disturbed surface and precipitation events. Additionally, water added to the pits during disposal operations for tasks like waste compaction and dust suppression introduces additional moisture to the system during disposal operations that could potentially provide a pathway for contaminants in the waste zone to migrate through the unsaturated zone. Modeling was conducted using the HYDRUS-2D/3D software to evaluate the spatial extent of saturation changes and fluxes across geologic layer interfaces in the unsaturated zone throughout the life cycle of a waste pit. A general 2-dimensional framework was developed that included a cross section of a waste pit and the underlying geologic units. Several geological layerings were developed to represent the variation across the mesa at Area G. The model was run stochastically for hundreds of realizations to understand how variations in hydraulic parameters (e.g., porosity, saturated hydraulic conductivity, Van Genuchten parameters, etc.) and operational parameters (e.g., pit open period duration, pit depth, initial saturation of the waste zone, etc.) affect the extent of saturation changes and fluxes in the deep unsaturated zone. Distributions for these parameters were developed based on available site data. Results of the unsaturated zone modeling indicate that a significant amount of water can reach the lower unsaturated zone under some circumstances, particularly when the amount of water introduced during pit operations is high. A statistical study of modeling results was performed to develop a regression that describes the variations of water flux in time at the geological layer interfaces. These statistical model results will be used to evaluate solute transport in a future effort. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

Effect of Minor Ce Additions on Corrosion Behavior of Experimental Pipeline Steel

Minor additions of rare earth elements (REEs) have been shown to improve various steel properties. In particular, Cerium (Ce), as a relatively abundant and inexpensive element, has received attention as a potentially beneficial minor alloying addition for a variety of steel applications, including pipelines materials. The objective of this work is to investigate the effect of Ce on corrosion performance of experimental high-strength pipeline steel. Electrochemical corrosion experiments were carried out on steel without and with 0.006, 0.018, and 0.03 wt.% of Ce in 3.5 wt.% NaCl saturated with CO2 at 20 oC. For comparison purposes, X100 carbon steel specimens machined from an experimental pipe with a yield strength of 731 MPa were tested under the same conditions. The electrochemical techniques employed included: potentiodynamic polarization (PDP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS). In addition, post-corrosion surface characterization was performed using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), while crystalline phases were determined by X-ray diffraction (XRD). The corrosion of base metal without Ce was lower (0.15 mm/y) compared to carbon steel X100 (0.9 mm/yr). The electrochemical results showed that adding Ce accelerates corrosion rates compared to base metal without Ce. No pitting corrosion of tested steel was detected.

Belarbi, Zineb↗
DOE OSTI2025

Texture Analysis of Inconel 718 with Different Modes During Single-Track Laser Surface Re-Melting

An in-depth understanding of the texture formation in melt pools allows for the modification of the surface layer microstructure and corresponding material properties, providing an opportunity to integrate laser surface re-melting into metal additive manufacturing. This study investigates crystallographic texture formation at different cooling rates in single melting tracks on the Inconel 718 (IN718) plate produced by laser surface re-melting. The cooling rate varies from 2.31 × 10 5 °C/s to 9.56 × 10 5 °C/s with the increase in scanning rates from 400 mm/s to 1200 mm/s, measured by recently developed real-time temperature monitoring of melt pools. Columnar grains are dominant, with distinct crystallographic textures forming in the melt pools. At a slower scanning speed, the keyhole mode shows three different textures forming at different depths (crystallographically layered structure), while, at a faster scanning speed, the conduction mode shows only random grain orientation. There are no pores/voids detected, and the columnar grain morphology and columnar grain width (8.6 μm to 12.4 μm) follow the analysis framework in terms of thermal gradient and solidification rate analysis. This implies that laser surface re-melting provides the potential to modify the surface structure from a random grain orientation to a crystallographically layered structure.

36 MATERIALS SCIENCE↗
NASA NTRS2019

Airspace Technology Demonstration 2 (ATD-2): Analysis of APREQ Flights at CLT

5/22/2019 National Aeronautics and Space Administration 1 Airspace Technology Demonstration 2 (ATD-2) Analysis of APREQ Flights at CLT May 22, 2019 5/22/2019 Objective 2 Quantify impact of IADS Phase 1 & 2 capabilities on APREQ flights at CLT with respect to: • Compliance to the Controlled Take Off Time (CTOT) • Benefits for APREQ flights that use IDAC to renegotiate for an earlier CTOT • Benefits of pre-scheduling APREQ flights using the Earliest Off Block Time (EOBT) • Relationship between EOBT compliance and rescheduling CTOT 5/22/2019 CLT APREQ Daily Compliance(Compliance Improvement Since ATD-2 Start) 3 Steady increase of APREQ compliance over the life of the project. Reduced variation in compliance leading to improved predictability. In addition to overall improved compliance into TBM systems, the predictability is increasing 5/22/2019 APREQ Compliance 10K Rolling Window 4 The most substantial APREQ compliance improvements started with Phase 2 capability (AEFS integration, ZTL IDAC, pre-scheduling and scheduler updates). 5/22/2019 IADS Phase 1 & 2 Benefit Mechanisms 5 1. Collaborative surface metering •Reduced engine run time •Reduced fuel consumption and emissions 2. Overhead stream operational integration a.Scheduling controlled flights at the gate •Reduced engine run time •Reduced fuel consumption and emissions b.APREQ renegotiating for an earlier slot •Reduced total delay •Passenger value of time and crew costs •Reduced engine run time •Reduced fuel consumption and emissions Benefits (1) and (2a) achieved through tactical gate holds Benefit (2b) achieved through APREQ renegotiation process described below Step 1: APREQ flight has a release time but is capable of taking off earlier Step 2: FAA TMC uses the IDAC green space / red space to identify and request an earlierslot in the overhead stream Step 3: Aircraft receives earlierrelease time and the difference between the release times is the reduction in delay 5/22/2019 Benefits for APREQ flights using IDAC to renegotiate for earlierCTOT 6 LBS Fuel 270.7 hours of delay saved by electronically renegotiating a better overhead stream time for 2,071 flights. • The benefits described here are associated with better use of existing capacity in the overhead stream, and technology to reduce surface delay. •These benefits are in addition to (distinct from) surface metering savings. 5/22/2019 APREQ Delay For Pre-Scheduled Flights into KATL Have Been Reduced and are More Predictable For the Last Five Months 7 Substantial Improvements in predictability of delay for the last 5 months 5/22/2019 EOBT Compliance / CTOT Reschedulefor Pre-Scheduled Flights into KATL 8 5/22/2019 Wrap-up 9 • Compliance to the CTOT has improved throughout the lifecycle of ATD-2 with biggest improvements following the introduction of Phase 2 capabilities • Rescheduling APREQ flights using IDAC has reduced 270.7 hours of delay at CLT • Predictability of local surface delay for APREQ flights is substantially improved via pre-scheduling with the IADS system • Pre-scheduled flights that reschedule for later times tend to call ready later with respect to EOBT

CLT↗
DOE OSTI2019

Effect of Ti on Ag catalyst supported on spherical fibrous silica for partial hydrogenation of dimethyl oxalate

A highly efficient Ag catalyst supported on a novel Ti-decorated spherical fibrous silica (Ag/Ti-KCC-1) was synthesized via a facile approach. Characterization of catalysts, including FT-IR, N2 physisorption, TEM, ICP-OES and DRUV-vis was carried out to investigate the physicochemical properties of the catalyst, XPS, H2-TPR, H2-TPD and DMO-TGA were conducted to further elucidate the effect of Ti dopant. It is shown that the Ti additive is able to, 1) inhibit the aggregation of Ag; 2) induce electron transfer from Ti to Ag, which effect the Ag dispersion and the adsorption ability of the reactants on the catalyst surface. Proper amount of Ti additive provided a balanced coverage of both hydrogen and dimethyl oxalate (DMO) on catalyst surface, which is essential in promoting the performance of the catalyst in the hydrogenation of DMO. By using the novel 10Ag/0.02Ti-KCC-1 catalyst, a high MG yield of 93.0% under extremely high WHSV of 1.75 h-1 is achieved.

silver, titanium, dimethyl oxalate, hydrogenation,↗
DOE OSTI2019

Finishing Surface Treatment of Potassium Titanyl Phosphate Single Crystals by Argon Cluster Ions

It is demonstrated that a argon cluster ion beam can be used for the finishing treatment of ultrasmooth surfaces (with initial root-mean-square roughness below 0.3 nm) of potassium titanyl phosphate single crystals. Analysis of the power spectral density function of surface roughness showed that cluster-ion irradiation leads to removal of residual chemical contaminations from the subsurface layer and produces additional smoothing of the crystal surface in a broad range of spatial frequencies (ν = 0.2–100 μm{sup –1}).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Copper Dendrites and Surface Engineering for Enhanced CO2 Reduction Research Report Paper

The electrocatalytic reduction of CO 2 (CO 2 R) into hydrocarbon fuels, such as ethylene and ethanol, provides an attractive pathway towards closing the industrial carbon cycle and producing chemicals using renewable electricity. Existing CO 2 R technologies can exhibit C 2+ product selectivity above 74% and operating current densities over 1.3 A/cm 2 , but none can achieve both simultaneously, limiting the commercial viability and scalability of this technology. Low CO 2 concentrations at the catalyst surface and competing side reactions such as the hydrogen evolution reaction (HER) inhibit C 2+ faradaic efficiencies and operational current densities. Additionally, the use of high surface area cathode geometries to increase operational current densities is under-investigated. In this work, we electrodeposit a macroporous copper dendrite film to form high surface area cathodes. These structures are then coated with a combination of hydrophobic/hydrophilic ionomers to achieve high electrochemically active surface areas (ECSA), form regions of intrinsic porosity, and maximize catalytic availability of CO 2 . Using these techniques, we hope to maximize C 2+ faradaic efficiencies (FE) and geometric partial current densities. The treated cathode compound macrostructure (~10μm-sized pores, and ~μm-long dendrites) and concomitant surface area allows increased geometric current densities while the ionomer coating simultaneously inhibits HER and increases hydrogen availability to improve C 2+ selectivity. Our results show that careful engineering of the catalyst-electrolyte interface can enhance CO 2 reduction product selectivity and efficiency.

10 SYNTHETIC FUELS↗
NASA NTRS1989

Characterization of Venera 15/16 Geologic Units from Pioneer Venus Reflectivity and Roughness Data

Geologic units have been defined for the surface of Venus from Venera 15/16 image data. A characterization of these geologic units is carried out using information on surface properties derived from Pioneer Venus (PV) reflectivity and rms slope data. The geologic context provided by Venera 15/16 units allows additional, more specific interpretations of surface radar properties to be made. Characterization of Venera units results in the definition of four groups of Venera units: (1) smooth rocky units, 2) rough rocky units, (3) rough high dielectric units, and (4) diffusely scattering units. On the basis of correlations of surface morphology to spatial and statistical distributions in rms slope and reflectivity data, we test models for the origin of the surface properties of some units. We conclude that plains and tectonic units can be contrasted in terms of the average roughness of the surface and that tectonic deformation appears to roughen the surface at 0.5- to 10-m and 5- to 50-cm scales. This tectonic weathering process appears to dominate the erosional regime of Venus. Unlike Earth or Mars, production and transport of soils dominates only a small portion (less than or equal to 5%) of the surface. Some of the Venera units display distinctive spatial and statistical distributions of PV radar data. In particular, apparent low reflectivity in the tesserae appears to be caused by small (5-50 cm) rock fragments on the surface which cause diffuse scattering at Pioneer Venus wavelengths. Analysis of models for the formation of these fragments suggests that they are due to the pervasive deformation undergone by the tesserae. Finally, aspects of this study have been used to extend results of Venera image data analysis southward of 30 deg. N lat, resulting in it prediction of the distribution of tessera. Such results can aid in Magellan investigations.

Bindschadler, D. L.↗
NASA NTRS2022

Simulating Mars: Enabling Testing of the Perseverance Rover Sampling and Caching Subsystem on Earth

The development of the Sampling and Caching Subsystem (SCS) on the JPL Perseverance Rover lies at the intersection of testing, robotics, and geology. The SCS team established three primary system test campaigns and venues to aid in the development of SCS through verification and validation testing – Qualification Model Dirty Testing (QMDT) to provide a venue for testing in a Martian environment, Vehicle System Testbed (VSTB) for testing while integrated with the mobility subsystem on Martian-like terrain, and the Flight Software Testbed (FSWTB) for conducting tests using the flight motor controllers and software system on a hexapod which had the ability to simulate rover tilt. Each venue contributed a vital piece to the SCS building blocks. However, the QMDT venue operating within a 10-ft diameter Thermal Vacuum chamber to simulate Martian environment provided a sui generis opportunity to fine tune the entire sampling and caching process while building the team’s knowledge base about rock drillability, system life, and target selection. On Earth, because Martian rocks are not readily available, the development team must utilize geoanalogs to the rocks and regolith on Mars. Geologists on the team helped establish a set of standard rock types to use for Mars missions, like Basalt, Sandstone, Mudstone, Gypsum, and other related geoanalogs. These geoanalogs are characterized with a standard suite of tests for density, compressibility, and other characteristics to categorize potential drillability. This concept of drillability is what links the geoanalogs on Earth to the samples we collect on Mars. With the simulant characteristics defined, these geoanalog rocks are ready to be drilled into as we do on the Martian surface. A key aspect of interacting with the surface on Mars is rock target identification and selection. The Perseverance robotic system uses the on-board cameras, instrumentation, and software to collect enough information to identify potential scientific targets. With the targets identified, SCS can place the Corer and abrade the surface or collect a sample. For a ground test activity like QMDT, the test team did not have all of the camera and instrumentation systems that the rover does, so the team developed ground test equivalents to process a rock, build a target map, and define the target. The team constructed a Rock Scanning Station to build a 3D point cloud of the rock. This point cloud was then processed and evaluated with predefined and programmed criteria in a Target Downselect Tool. A primary output of the Target Downselect Tool is a defined target that can be uploaded directly to the robotic software system to simulate and build the robotic sequences used in tests. With these insights and programmatic definition of targets, the QMDT test team was able to make the same decisions that the Perseverance surface operations team does. In addition, valuable lessons learned from developing the target selection ground tools and using them were implemented into the tools used for surface operations.

Kim, Junggon↗
NASA NTRS2010

A Comparison of Oxidized Carbon Abundances among Comets

Comets contain relatively well preserved icy material remaining from the epoch of Solar System formation, however the extent to which these ices are modified from their initial state remains a fundamental question in cometary science. As a comet approaches the Sun, sublimation of the ices contained in its nucleus (termed " native ices") releases parent volatiles into the coma, where they can be measured spectroscopically. One means of assessing the degree to which interstellar ices were processed prior to their incorporation into cometary nuclei is to measure the relative abundances of chemically-related parent volatiles. For example, formation of C2H6 by hydrogen atom addition (e.g., to C2H2) on surfaces of ice-mantled grains was proposed to explain the high C2H6 to CH4 abundance observed in C/1996 B2 (Hyakutake) [1]. The large C2H6/CH4 abundance ratios measured universally in comets, compared with those predicted by gas phase production of C2H6, establishes H-atom addition as an important and likely ubiquitous process. CO should also be hydrogenated on grain surfaces. Laboratory irradiation experiments on interstellar ice analogs indicate this to require very low temperatures (T approx. 10-25 K), the resulting yields of H2CO and CH3OH being highly dependent both on hydrogen density (i.e., fluence) and on temperature ([2],[3]). This relatively narrow range in temperature reflects a lack of mobility below 8-10 K on the one hand, and reduced sticking times for H-atoms as grain surfaces are warmed above 20 K on the other. The relative abundances of these three chemically-related molecules in comets provides one measure of the efficiency of H-atom addition to CO on pre-cometary grains (Fig. 1).

DiSanti, M. A.↗
DOE OSTI2022

Systems and methods for application of stress corrosion cracking resistant cold spray coatings

Systems and methods for application of stress corrosion cracking resistant cold spray coatings include a method of forming a partial coating on a canister having a perimeter wall with a surface. The method may include identifying a compromised region on the surface of the wall of the canister, and impacting a substantially linear flow of particles of a powder against an area in the compromised region of the surface in a manner effective to cause the particles of the powder to bond to the surface of the wall to produce a coating on the area of the compromised region. The method may also include moving the substantially linear flow in a direction substantially parallel to the surface of the wall to cause the particles to impact an additional area of the compromised region to cause the particles to bond to the surface of the additional area.

Johnson, Kyle William↗
DOE OSTI2024

INTERDUNE DEPOSITS AND STRATIGRAPHIC FRAMEWORK OF THE NAVAJO SANDSTONE IN THE LAKE POWELL AREA, UTAH, USA

The Western Interior of the USA was dominated by desert environments for much of the Jurassic. Of these desert environments, the most extensive by far was the Navajo Sandstone erg, which, in conjunction with its correlative Nugget and Aztec Sandstones, is thought to have covered well over 500,000 km2, and is one of the largest ergs preserved in the rock record. The Navajo Sandstone is also one of a few geologic units which show promise as a potential CO2 sequestration reservoir in Utah. It outcrops along the eastern and southern margin of the state, and subcrops throughout most of the central area. The Navajo Sandstone consists of stacked eolian deposits, composed of well sorted, clean sandstone, deposited in commonly tabular, high angle cross bedded paleodunes, which are on average 15 m thick. Interspersed between these paleodunes are interdune deposits. Interdune deposits consist of sandy to calcareous, predominantly planar bedded, lensoid units, ranging from <1 m up to 7 m thick. In some cases, these interdune deposits occur along more extensive stratigraphic bounding surfaces. Dating within the Navajo Sandstone has historically been very difficult, as a result of its predominantly clean, aeolian sandstone composition. In addition, complexity of internal stratigraphic surfaces coupled with a low structural dip and generally flat topography has resulted in a poor understanding of the internal stratigraphy of the Navajo Sandstone. Exceptional three-dimensional exposures of the Navajo Sandstone in the upper portions of Lake Powell permit us to relate interdune carbonates to a hierarchical bounding surfaces model. Here we use this combined approach to interpret the internal stratigraphy of the Navajo Sandstone in this region. This work forms part of a larger study of the Navajo Sandstone across Utah and its potential as a CO2 reservoir, by developing a more comprehensive stratigraphic framework, and increasing understanding of stratigraphic complexity within one of the most significant eolian systems in the world.

Mahon, Elizabeth↗