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NASA NTRS2013

NDE Evidence for the Damage Arrestment Performance of PRSEUS Composite Cube During High-Pressure Load Test

As an approach to light-weight, cost-effective and manufacturable structures required to enable the hybrid wing body aircraft, The Boeing Company, Inc. and NASA have developed the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept. A PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept as part of a building block approach for technology development of the PRSEUS concept. The overall specimen strength exceeded the 18.4 psi load requirement as testing resulted in the cube reaching a final pressure load of around 48 psi prior to catastrophic failure. The cube pressure test verified that the joints and structure were capable of sustaining the required loads, and represented the first testing of joined PRSEUS structure. This paper will address the damage arrestment performance of the stitched PRSEUS structure. Following catastrophic failure of the cube, ultrasonic pulse-echo inspection found that the localized damage, surrounding a barely-visible impact damage site, did not change noticeably between just after impact and catastrophic failure of the cube, and did not play a role in the catastrophic failure event. Ultrasonic inspection of the remaining intact cube panels presented three basic types of indications: delaminations between laminae parallel to the face sheets, lying between face sheet and tear strap layers, or between tear strap and flange layers; delaminations above the noodles of stringers, frames or integral caps, lying within face sheet or tear strap layers; and delaminations between the laminae in the inner fillets of the integral caps, where pulloff stresses were expected to be highest. Delaminations of all three types were predominantly contained by the first row of stitches encountered. For the small fraction of delaminations extending beyond the first row of stitches, all were contained by the second stitch row.

Johnston, Patrick H.↗
NASA NTRS2013

Analysis and Results from a Flush Airdata Sensing (FADS) System in Close Proximity to Firing Rocket Nozzles

This presentation presents information regarding the nose-cap flush airdata sensing (FADS) system on Orion's Pad Abort 1 (PA-1) vehicle. The purpose of the nose-cap FADS system was to test whether or not useful data could be obtained from a FADS system if it was placed in close proximity to firing rockets nozzles like the attitude control motor (ACM) nozzles on the PA-1 launch abort system (LAS). The nose-cap FADS systems use pressure measurements from a series of pressure ports which are arranged in a cruciform pattern and flush with the surface of the vehicle to estimate values of angle of attack, angle of side-slip, Mach number, impact pressure and free-stream static pressure.

Pad Abort 1↗
NASA NTRS2014

A Novel Hybrid Ultramicrotomy/FIB-SEM Technique: Preparation of Serial Electron-Transparent Thin Sections of a Hayabusa Grain

The Japanese space agency's (JAXA) Hayabusa mission returned the first particulate samples (typically <100micron) from the surface of an asteroid (25143 Itokawa). These precious samples provide important insights into early Solar System processes, but their sizes pose tremendous challenges to coordinated analysis using a variety of nano- and micro-beam techniques. The ability to glean maximal information from individual particles has become increasingly important and depends critically on sample preparation. We developed a hybrid technique combining traditional ultramicrotomy with focused ion beam (FIB) techniques, allowing for more thorough in situ investigations of grain surfaces and interiors. Using this method, we increase the number of FIB-prepared sections that can be recovered from a particle with dimensions on the order of tens of microns. These sections can be subsequently analyzed using a variety of analytical techniques. Particle RA-QD02-0211 is a approx. 40×40×20 micron particle from Itokawa containing olivine and Fe sulfides. It was embedded in low viscosity epoxy and partly sectioned to a depth of approx 10 micron; sections are placed on Cu grids with thin amorphous films for transmission electron microscope (TEM) analyses. With the sample surface partly exposed, the epoxy bullet is trimmed to a height of approx. 5mm to accommodate the allowable dimensions for FIB work (FEI Quanta 600 3D dual beam FIB-SEM). Using a diamond trim knife, the epoxy surrounding the grain is removed on 3 sides (to within a few microns of the grain); the depth of material removed extends well below the bottom of the particle. The sample is attached to an SEM pin mount, the epoxy coated with conductive paint, and the entire assembly coated with approx. 40nm of carbon to eliminate sample charging during FIB work. A protective carbon cap is placed according to the plan for the 15 FIB sections. The central 'spine' of the cap runs perpendicular to the front of the sample, and the 'ribs' protruding from either side run parallel. Each rib indicates the location of a planned FIB section, and the spine contains the final two planned sections. We use a cap with a 4 micron-wide spine and 2micron-wide ribs that have ≳3.5 micron of space between them (narrower cuts result in too much re-deposition of material inside the trenches). Using a 30kV, 3nA ion-beam we expose the front surface of the grain and commence milling trenches between sections. Rather than using the typical C-cut to prepare the sample for lift-out, an L-cut is used instead, leaving the sample connected by an interior tab. tab. Sections are lifted out, attached to TEM grids and thinned to electron transparency. TEM analyses show that our hybrid technique preserves both interior and edge features, including surface modifications from exposure to the space environment, such as damaged rims that form in response to solar wind implantation effects and adhering grains. In addition, the FIB sections provide larger areas that are free of fractures and chatter effects in comparison to the microtome thin sections, thus enabling more accurate measurements of solar flare particle track densities that are used to determine the surface exposure age of the particles.

Berger, Eve L.↗
NASA NTRS2016

Growth Chambers on the International Space Station for Large Plants

The International Space Station (ISS) now has platforms for conducting research on horticultural plant species under LED lighting, and those capabilities continue to expand. The 'Veggie' vegetable production system was deployed to the ISS as an applied research platform for food production in space. Veggie is capable of growing a wide array of horticultural crops. It was designed for low power usage, low launch mass and stowage volume, and minimal crew time requirements. The Veggie flight hardware consists of a light cap containing red (630 nm), blue, (455 nm) and green (530 nm) LEDs. Interfacing with the light cap is an extendable bellows/baseplate for enclosing the plant canopy. A second large plant growth chamber, the Advanced Plant Habitat (APH), is will fly to the ISS in 2017. APH will be a fully controllable environment for high-quality plant physiological research. APH will control light (quality, level, and timing), temperature, CO2, relative humidity, and irrigation, while scrubbing any cabin or plant-derived ethylene and other volatile organic compounds. Additional capabilities include sensing of leaf temperature and root zone moisture, root zone temperature, and oxygen concentration. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs (4100K). There will be several internal cameras (visible and IR) to monitor and record plant growth and operations. Veggie and APH are available for research proposals.

Advanced Plant Habitat↗
NASA NTRS2016

Growth Chambers on the International Space Station for Large Plants

The International Space Station (ISS) now has platforms for conducting research on horticultural plant species under LED (Light Emitting Diodes) lighting, and those capabilities continue to expand. The Veggie vegetable production system was deployed to the ISS as an applied research platform for food production in space. Veggie is capable of growing a wide array of horticultural crops. It was designed for low power usage, low launch mass and stowage volume, and minimal crew time requirements. The Veggie flight hardware consists of a light cap containing red (630 nanometers), blue, (455 nanometers) and green (530 nanometers) LEDs. Interfacing with the light cap is an extendable bellowsbaseplate for enclosing the plant canopy. A second large plant growth chamber, the Advanced Plant Habitat (APH), is will fly to the ISS in 2017. APH will be a fully controllable environment for high-quality plant physiological research. APH will control light (quality, level, and timing), temperature, CO2, relative humidity, and irrigation, while scrubbing any cabin or plant-derived ethylene and other volatile organic compounds. Additional capabilities include sensing of leaf temperature and root zone moisture, root zone temperature, and oxygen concentration. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs (4100K). There will be several internal cameras (visible and IR) to monitor and record plant growth and operations. Veggie and APH are available for research proposals.

Veggie↗
NASA NTRS2016

My Internship at NASA

My name is Isaac Lopez and I am a junior at the University of Houston majoring in Mechanical Engineering Technology. I will be completing my first tour at the NASA-Johnson Space Center ("JSC") as a Mechanical Engineer within the Human Interfaces Branch. Throughout my tour, I was given the opportunity to work on multiple projects that have expanded my knowledge and interest in acoustics and engineering design. One of the projects I worked on at JSC consisted of doing acoustic simulation of the EVA comm. cap. While working on the comm. cap headset, my main duty consisted of simulating the acoustics of the headset to find a solution to the condensing water that can accumulate and block the acoustic tube, causing attenuation or complete loss of audio in one ear for an astronaut using the EVA. For this project, I had to create a Creo model of the comm. cap so that I would be able to import it into Comsol for acoustic simulation. I also had the opportunity to design a portable and lightweight beam degrader for the EEE Parts and Radiation team. With the help of Creo, I was able to make a CAD design and put together a small working prototype for the radiation team to demonstrate the capabilities that the beam degrader had. In addition to these projects, JSC allowed me to work closely on projects with other interns. I had the opportunity to help another intern with his acoustic diverter, intended to improve the sound quality in Node 1 of the ISS. During this project, I helped with some of the acoustic testing inside the anechoic chamber as well as helping record data during testing at the ISS mock up. During the course of my first tour, I was able to learn and continually improve on my CAD drafting skills. With each project I worked on, I acquired new ways to create and improve various designs with various constraints. Furthermore, I also had the opportunity to work with electrical engineers and learn about the electronic components that would provide control of the beam degrader functions. I was able to take the knowledge, skills and designs I had acquired during my tour at JSC (such as Finite Element Analysis) and apply them to my work on the Comsol Multiphysics software for acoustics simulation. I was also able to use it to do some stress analysis on a proposed design for a proposed Habitat structure. My time at JSC has been invaluable as it helped me grow and more fully-comprehend my major as well as spark an interest in acoustics and how much it relates to mechanical engineering. This internship has taught me that engineering is much more than a profession - it is embedded in our daily lives as a puzzle that requires critical thinking as an everyday challenge that makes life more interesting.

Lopez, Isaac↗
NASA NTRS2016

Effect of Interhemispheric Currents on Equivalent Ionospheric Currents in Two Hemispheres: Simulation Results

In this research, we used numerical simulation to study the effect of interhemispheric field-aligned currents (IHCs), going between two conjugate ionospheres in two hemispheres, on the equivalent ionospheric currents (EICs). We computed the maps of these EICs In two hemispheres during summer-winter conditions, when the effect of the IHCs is especially significant. The main results may be summarized as follows. In winter hemisphere, the IHCs may significantly exceed and be a substitute for the local R1 currents, and they may strongly affect the magnitude, location, and direction of the EICs In the nightside winter auroral ionosphere. While in summer polar cap the EICs tend to flow sunward, and in winter polar cap the EICs turn toward dawn due to the effect of the IHCs. The well-known reversal in the direction of the EICs in the vicinity of the midnight meridian, in winter hemisphere, is observed not at the polar caps boundary (as usually expected) but equatorward of this boundary in the region of the IHCs location. The IHCs in winter hemisphere may be, in fact, not only a substitute for the R1 currents but also the major source of the Westward Auroral Electrojet, observed In both hemispheres during substorm activity.

Lyatsky, Sonya↗
NASA NTRS2019

Integrated Circuit (IC) Chip with a Self-Contained Fluid Sensor and Method of Making the Chip

An integrated circuit (IC) chip with a self-contained fluid sensor and method of making the chip. The sensor is in a conduit formed between a semiconductor substrate and a non-conductive cap with fluid entry and exit points through the cap. The conduit may be entirely in the cap, in the substrate or in both. The conduit includes encased temperature sensors at both ends and a central encased heater. The temperature sensors may each include multiple encased diodes and the heater may include multiple encased resistors.

Manos, George↗
NASA NTRS2016

Mid and Thermal Infrared Remote Sensing at the Jet Propulsion Laboratory

The mid and thermal infrared (MTIR) for the Earth surface is defined between 3 and 14µm. In the outer solar system, objects are colder and their Planck response shifts towards longer wavelengths. Hence for these objects (e.g. icy moons, polar caps, comets, Europa), the thermal IR definition usually stretches out to 50µm and beyond. Spectroscopy has been a key part of this scientific exploration because of its ability to remotely determine elemental and mineralogical composition. Many key gas species such as methane, ammonia, sulfur, etc. also have vibrational bands which show up in the thermal infrared spectrum above the background response. Over the past few decades, the Jet Propulsion Laboratory has been building up a portfolio of technology to capture the MTIR for various scientific applications. Three recent sensors are briefly reviewed: The airborne Hyperspectral thermal emission spectrometer (HyTES), the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) and Mars Climate Sounder (MCS)/DIVINER. Each of these sensors utilize a different technology to provide a remote sensing product based on MTIR science. For example, HyTES is a push-brooming hyperspectral imager which utilizes a large format quantum well infrared photodetector (QWIP). The goal is to transition this to a new complementary barrier infrared photodetector (CBIRD) with a similar long wave cut-off and increased sensitivity. ECOSTRESS is a push-whisk Mercury Cadmium Telluride (MCT) based high speed, multi-band, imager which will eventually observe and characterize plant/vegetation functionality and stress index from the International Space Station (ISS) across the contiguous United States (CONUS). MCS/DIVINER utilizes thermopile technology to capture the thermal emission from the polar caps and shadow regions of the moon. Each sensor utilizes specific JPL technology to capture unique science. similar long wave cut-off and increased sensitivity. ECOSTRESS is a push-whisk Mercury Cadmium Telluride (MCT) based high speed, multi-band, imager which will eventually observe and characterize plant/vegetation functionality and stress index from the International Space Station (ISS) across the contiguous United States (CONUS). MCS/DIVINER utilizes thermopile technology to capture the thermal emission from the polar caps and shadow regions of the moon. Each sensor utilizes specific JPL technology to capture unique science.

Johnson, William R.↗
NASA NTRS2020

The Stratigraphy of Central and Western Butte and the Greenheugh Pediment Contact

The Greenheugh pediment at the base of Aeolis Mons (Mt. Sharp), which may truncate units in the Murray formation and is capped by a thin sandstone unit, appears to represent a major shift in climate history within Gale crater. The pediment appears to be an erosional remnant of potentially a much more extensive feature. Curiosity’s traverse through the southern extent of Glen Torridon (south of Vera Rubin ridge) has brought the rover in contact with several new stratigraphic units that lie beneath the pediment. These strata were visited at two outcrop-forming buttes (Central and Western butte- both remnants of the retreating pediment) south of an orbitally defined boundary marking the transition from the Fractured Clay-bearing Unit (fCU) and the fractured Intermediate Unit (fIU). Here we present preliminary interpretations of the stratigraphy within Central and Western buttes and propose the Western butte cap rocks do not match the pediment capping unit.

Bryk, A. B.↗
NASA NTRS2020

Atmospheric Carbon Cycle Dynamics Over the Above Domain: an Integrated Analysis Using Aircraft Observations (Arctic-CA) and Model Simulations (GEOS)

The Arctic Carbon Atmospheric Profiles (Arctic-CAP) project conducted six airborne surveys of Alaska and northwestern Canada between April and November 2017 to capture the spatial and temporal gradients of northern high-latitude carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO) as part of NASA's Arctic-Boreal Vulnerability Experiment (ABoVE). The Arctic-CAP sampling strategy involved acquiring vertical profiles of CO2, CH4 and CO from the surface to 5 km altitude at 25 sites around the ABoVE domain on a 4- to 6-week time interval. We observed vertical gradients of CO2, CH4 and CO that vary by eco-region and duration of the sampling period, which spanned the majority of the seasonal cycle. All Arctic-CAP measurements were compared to a global simulation using the Goddard Earth Observing System (GEOS) modeling system. Comparisons with GEOS simulations of atmospheric CO2, CH4 and CO highlight the potential of these multi-species observations to inform improvements in surface flux estimates and the representation of atmospheric transport. GEOS simulations provide estimates of the near surface average CO2 and CH4 enhancements that are well correlated with aircraft observations (R=0.74 and R=0.60 respectively), suggesting that GEOS has reasonable fidelity over this complex and heterogeneous region. This model-data comparison over the ABoVE domain reveals that while current state-of-the-art models and flux estimates are able to capture broadscale spatial and temporal patterns in near-surface CO2 and CH4 concentrations, more work is needed to resolve fine-scale flux features that are observed. The study also provides a framework for benchmarking a global model at regional scales, which is needed to use climate models as tools to investigate high-latitude carbon-climate feedbacks.

C Sweeney↗
NASA NTRS2021

The impacts of warming on rapidly retreating high-altitude, low-latitude glaciers and ice core-derived climate records

Alpine glaciers in the low- and mid-latitudes respond more quickly than large polar ice sheets to changes in temperature, precipitation, cloudiness, humidity, and radiation. Many high-altitude glaciers are monitored by ground observations, aerial photography, and satellite-borne sensors. Regardless of latitude and elevation, nearly all nonpolar glaciers and ice caps are undergoing mass loss, which compromises the records of past climate preserved within them. Almost without exception, the retreat of these ice fields is persistent, and a very important driver is the recent warming of the tropical troposphere and oceans. Here we present data on the decrease in the surface area of four glaciers from low- to mid-latitude mountainous regions: the Andes of Peru and northern Bolivia, equatorial east Africa, equatorial Papua, Indonesia, and the western Tibetan Plateau. Climate records based on oxygen isotopic ratios (δ18O) measured in ice cores drilled from several glaciers in these regions reveal that the records from elevations below ~6000 m above sea level have been substantially modified by seasonal melting and the movement of meltwater through porous upper firn layers. Fortunately, δ18O records recovered from higher altitude sites still contain well-preserved seasonal variations to the surface; however, the projected increase in the rate of atmospheric warming implies that climate records from higher elevation glaciers will eventually also be degraded. A long-term ice core collection program on the Quelccaya ice cap in Peru, Earth's largest tropical ice cap, illustrates that the deterioration of its climate record is concomitant with the increase in mid-troposphere temperatures. The melting ice and resulting growth of proglacial lakes presents an imminent hazard to nearby communities. The accelerating melting of glaciers, if sustained, ensures the eventual loss of unique and irreplaceable climate histories, as well as profound economic, agricultural, and cultural impacts on local communities.

Low-latitude glaciers↗
NASA NTRS2021

A Geodetic and Positioning Thematic Layer - Identifying tools to connect the GGRF and IGIF

Effective and sustainable modernization of a nation’s geodetic framework relies on the ability of the relevant organizations and other stakeholders to communicate, integrate, and align both their strategic objectives and operational planning with the United Nations Committee of Experts on Global Geospatial Information Management (UN GGIM) Sub-Committee on Geodesy’s (SCoG) roadmap for a Global Geodetic Reference Frame (GGRF) for Sustainable Development. In addition, to implement geodetic modernization initiatives through multiple government agencies, a holistic country action plan (CAP) for geospatial information management must incorporate pertinent geodetic outcomes and outputs. Presently, the CAP framework and principles used by nations is the UN GGIM Integrated Geospatial Information Framework (IGIF). From engagement with geospatial and survey communities across emerging nations in the Asia Pacific region, it is evident more assistance and coordination is necessary to articulate, integrate and connect geodetic organizational strategies with the requirements of the GGRF roadmap; the strategic pathways of the IGIF; and resourcing for a meaningful and relevant multi-faceted CAP. One of the supporting mechanisms for such planning or preparation, which representatives of the International Federation of Surveyors (FIG) Asia Pacific Capacity Development Network (AP CDN) and the UN SCoG Education, Training and Capacity Building (ETCB) working group are considering, is a policy framework and guide for a “Geodetic and Positioning Thematic Layer” (GPTL). Essentially, this “thematic layer”, in terms of the GGRF and IGIF, aims to provide a comprehensive understanding of, and a toolbox for, the “why, what, how, and who” of geodesy and positioning. This discussion paper will provide background and insights for a GPTL dedicated to recognizing, and aligning the geodetic capacity development needs with broader geospatial information management issues and applications. The paper will also outline a rigorous, participatory, and inclusive consultation process for the design and development of a thematic layer. Furthermore, as the intention of the authors is to prepare a forthcoming “white paper” that will concisely describe the issues of a GPTL and initiatives for an appropriate guide and/or policy framework, this paper will seek feedback on: the potential scientific, social, environmental and political benefits of modernizing geodetic infrastructure and systems; the challenges associated with the GGRF roadmap; leveraging the geodesy-relevant elements of each IGIF strategic pathway; the importance of collaborative efforts; and the capacity development needs and resources in relation to governance, technology and people.

SARIB, Rob↗
NASA NTRSDate not supplied

X-Ray Computed Tomography of Apollo Drive Tube 73001 as Part of the Apollo Next Generation Sample Analysis Program

Introduction: Starting in 2019, the Apollo Next Generation Sample Analysis (ANGSA) Program has enabled consortium studies of specially curated Apollo samples that were previously unstudied (or under studied). This program was intended as a participating scientist program for these Apollo samples, as well as a preparation for upcoming lunar sample return missions (e.g., Artemis). The work began with studies of unsealed core tube 73002 [1,2] that is the upper ~35 cm of an Apollo 17 double drive tube (~70 cm total depth) collected on the landslide deposit near Lara Crater at Station 3 in the Taurus Littrow Valley. More recently the program extended to the study of a variety of frozen Apollo 17 samples [3], as well as the gas extraction [4] and dissection [5] of 73001, the lower half of the station 3 double drive tube. Sample 73001 was sealed under vacuum on the Moon in a Core Sample Vacuum Container (CSVC). In this abstract we will examine the role of X-ray Computed Tomography (XCT) during the preliminary examination process for sealed core 73001, including: (1) engineering scans to aid in understanding the gas extraction process, (2) whole-core scanning prior to opening to inform extrusion and dissection work, and (3) individual particle scanning to characterize rock fragment lithologies for follow on studies. Methodology: Sample 73001 is a 33 cm long, 4 cm diameter regolith sample collected inside a lunar drive tube (~1 mm aluminum walls). That drive tube was sealed inside a 0.5 mm thick stainless steel (SS) CSVC. XCT scans for engineering purposes were done on the Nikon XTH 320 system at Johnson Space Center using the 225 kV multi-metal reflection source at 215 kV, 179 A, and a 38.49 m voxel size. Individual >4 mm particles separated from the core during processing (then triply sealed in Teflon bags) were also scanned at JSC using the 180 kV source at 90 kV, 33 A, and a 2.98 – 10.65 m voxel size. Whole-core scans were done at the University of Texas High-Resolution X-ray Computed Tomography Facility (UTCT) on the 225 kV reflection source on the North Star Imaging cabinet XCT system. These scans included: (1) a series of 9 overlapping super-resolution scans each covering a ~4 cm length of the tube at 190 kV, 180 µA, and a 12.9 µm voxel size and (2) a lower resolution continuous helical scan of the entire core at 190 kV, 180 µA, and a 51.8 µm voxel size. Progress and Results: Before piercing and extracting the gas from sample 73001, an XCT scan of the bottom portion of the CSVC was used to confirm the location of the Teflon cap on the inner drive tube and whether there was an “air” gap between the Teflon cap and the CSVC. This was to ensure the Teflon cap (which immobilized the soil inside the drive tube) was not accidentally pierced during gas extraction. Similarly, after piercing, the bottom and top portions of the CSVC were scanned in order to capture engineering knowledge about the results of the piercing process, as well as the metal knife edge vacuum seal (SS into an In-Ag alloy). Both scans will provide constraints on future work of this type, both for the design of tools used on the lunar surface during Artemis, as well as how we open future samples of this type. An unexpected finding from these engineering scans was that the device in the drive tube that immobilizes the regolith (the keeper) was not seated in the tube properly. This meant that (1) the drive tube could not be removed from the CSVC for the trip to UTCT, and (2) the procedure for opening and extruding the drive tube had to be modified. Had either of these things not been known prior to opening the CSVC, it could have led to an inability to XCT scan the whole core at high resolution and/or potential disruption of the core stratigraphy during extrusion. At UTCT, the entire length of the core was scanned at high resolution (12.9 microns per voxel). This scan serves multiple purposes: (1) A lower resolution (and uncorrected) version of these scans stitched together was used to help inform the processors of potential pitfalls during extrusion and dissection (voids, angular fragments at the edges of the sample, etc.); and (2) the full resolution corrected data will serve as the permanent in situ record of the stratigraphy of the sample and will enable future researchers to perform a variety of analyses. All 121 >4 mm particles separated during dissection pass 1 of sample 73001 have been individually scanned. These scans clearly show the lithology of each particle while keeping the particles in pristine condition (they are individually triply bagged in Teflon within our N2 purged processing cabinets). Because of the dust adhering to particle exteriors, it would otherwise be impossible to determine lithologies in a non-contaminating way. Thus far the types of lithologies seen in sample 73001 (e.g., regolith breccias, impact-melt breccias, agglutinates, and bas-alts) are similar to those previously identified in sample 73002 [2]. By the time of the meeting, all particles from all 3 dissection passes will have been scanned and statistics on the different lithologies in 73001 compiled. References: [1] Shearer et al. (2020) 51st LPSC, abstract 1181. [2] Zeigler et al. (2020) 51st LPSC, abstract 3023. [3] Kent et al. (2022) This Volume. [4] McDonald et al. (2022) European Lunar Symposium. [5] Gross et al (2022) This volume.

Moon↗
NASA NTRS2022

Exploring the Clouds of Venus: Science Driven Aerobot Missions to Our Sister Planet

Venus is essential to our understanding of the evolution and habitability of Earth-size planets throughout the galaxy. The selection of the VERITAS, EnVision, and DAVINCI missions by NASA and ESA in June 2021 is an important step in advancing the science. However, addressing many of the most challenging questions will require in situ platforms that can operate in the Venus environment for extended periods in order to capture the full complexity of our sister planet. Aerobots are aerial vehicles that exploit buoyancy to achieve long-duration operation in the Venus cloud layer where environmental conditions are comparatively benign. Buoyancy control, explained in more detail in a companion paper at this conference, allows aerobots to change altitude with little energy expenditure enabling new scientific measurement opportunities. These include atmospheric chemistry, dynamics, geophysical measurements of the crust and interior and geological investigations enabled by high resolution surface imaging. One aspect to our approach to defining missions that fit within the resource constraints of competitive missions is keeping the scale small. Today’s science-driven appetite for sophisticated measurements and large volumes of data is driving size upwards but advances in technology can enable aerobots that can be delivered to Venus at manageable costs. The other aspect is supporting the aerobot at Venus with orbiters providing data relay, localization and synergistic science. The recently selected orbiters, equipped with low-cost proximity relay systems routinely used at Mars may obviate the need for dedicated orbiters thereby enabling Discovery mission candidates. Four aerobot mission concepts have been defined which fit comfortably within the current New Frontiers (NF) cost cap ($900M in $FY22). One of these concepts would also be a candidate for a Discovery mission if that cost cap ($500M in $FY19) were raised. Raising the NF cost cap would enable more capable aerobot missions combining both altitude control with synergistic orbital observations. Investigations of surface geology at high resolution with subcloud NIR nightside imaging and dropsondes on the dayside of Venus could also benefit from collaborations with foreign contributions.

"O'Rourke, Joseph"↗
NASA NTRSDate not supplied

Toward Fully 3D-Printed Two Degree of Freedom Acoustic Liners

An acoustic liner optimization tool is developed for designing two degree of freedom (2DOF) liners with high absorption over a wide range of frequencies and sound pressure levels (SPLs). Two additively manufactured 2DOF liners (one constant and one variable chamber depth) are designed and printed with an embedded perforate layer as the septum. A normal incidence impedance tube study is performed to directly compare impedance and absorption spectra to a more traditionally manufactured 2DOF liner with embedded mesh caps in phenolic honeycomb. Comparisons of test data to predictions are shown as well as SPL sensitivities for each acoustic liner. Broadband absorption is achieved with the 3D printed 2DOF liner containing constant chamber depths, although due to current limitations in printed embedded perforate hole size, not as broad as the traditional mesh cap liner. However, results also show that the 3D printed variable chamber depth sample is more comparable to the mesh cap liner absorption, demonstrating the viability of printed embedded perforates in novel concepts.

acoustic liner 2DOF two degree of freedom 3D print↗
DOE OSTI2022

Muconic Acid Production from P. putida Using High Protein Algae Hydrolysate

The composition of algal biomass is highly dynamic, with protein, lipid, and carbohydrate contents varying in response to nutrient and environmental conditions during cultivation. Because shifts in biomass composition are often associated with reduced biomass productivity, production costs can often increase if targeting higher biomass compositional quality (enriched in carbohydrates or lipids at reduced protein content) as input for the algal biorefinery. The optimal algal biorefinery configuration is thus a function of many factors. One of the key strengths of the Combined Algal Processing (CAP) process is the versatility of feedstocks and products produced. The concept has been demonstrated with ethanol and a variety of carboxylic acids (succinic, butyric, muconic) as coproducts along with lipid upgrading to biofuel. Modification of the approaches, processes and downstream upgrading to fuels has allowed the CAP process to reduce costs and improve efficiency. Muconic acid is a high-value, potential fermentation coproduct of interest because it can be easily converted to adipic acid, a high-volume monomer for the production of nylon and other valuable consumer plastics. As such, the production of muconic acid through CAP was explored to expand the suite of products from algal biomass and to begin exploring the valorization of high protein content biomass from rapidly grown algae biomass. We have established initial performance parameters and shown that the range of substrates consumed by the muconic acid-producing microbe, Pseudomonas putida, includes at least glucose, mannose, glycerol, and lactic acid. We achieved complete utilization of these four major hydrolysate substrates achieving productivities of 0.037 (g/L/h) from Scenedesmus obliquus and 0.029 (g/L/h) from Monoraphidium minutum hydrolysates. Final titer and process yield (mol of muconic acid per mol of substrate (molP/molS)) were 0.99 g/L and 0.42 molP/molS from S. obliquus hydrolysate and 0.75 g/L and 0.23 molP/molS from M. minutum hydrolysate, respectively.

BIOMASS FUELS↗
DOE OSTI2022

Coalescence of GaP on V-Groove Si

In recent years, better understanding and control over the formation of crystalline defects during the direct epitaxy of III-V semiconductors on Si substrates via metal organic vapor phase epitaxy (MOVPE) has enabled large gains in III-V-on-Si solar cell efficiency, pointing to pathway to lower-cost, high-performance III-V solar cells. However, such results have only been achieved on costly chemo-mechanically-polished (CMP) Si wafers. The use of V-groove nanopatterned Si substrates has demonstrated similarly high-crystalline-quality III-V-on-Si epitaxy, but also can be combined with lower-cost polishing techniques. Although they offer a potential cost advantage, growth on V-groove substrates adds challenges not present for epitaxy on planar wafers (the III-V material must be coalesced into a thin film after an initial nucleation stage). MOVPE growth conditions that promote highly facet-selective lateral growth needed for coalescence are generally actively avoided for conventional thin fim growth, so growth conditions need to be re-developed for V-groove-based epitaxy. Additionally, coalescence add complexity to the dislocation dynamics related to lattice relaxation, so strategies used to keep threading dislocation density (TDD) low on planar substrates need to be re-tuned for V-grooves. We have studied the morphological evolution and dislocation dynamics of GaP grown on V-groove Si by MOVPE. Growth conditions of V/III=5,000 and Tg=800 degrees C were uniquely found to produce extremely smooth coalesced thin films, with an RMS roughness of 0.2 nm measured by AFM. Additionally, at this growth condition, we identified two regimes of growth determined by the width of the SiNx cap (a remnant of the nanopatterning process) at the top of the V-grooves. For narrow caps, the GaP coalesces into a thin film, and for wide caps, the GaP evolves into {1 1 1}-faceted diamonds that do not coalesce. We suggest the influence of Si from the sidewalls of the V-grooves on the surface reconstruction of the GaP as the mechanism for this effect, with reflection difference spectroscopy (RDS) and Si doping experiments supporting this theory. In addition to morphology, the dislocation dynamics of the system were studied with electron channeling contrast imaging (ECCI) and transmission electron microscopy (TEM). The TDD of the coalesced GaP films was found to be 5 x 10^7 cm^-2 after coalescence via ECCI, a level still too high for high-quality solar cells. However, misfit dislocations crossing multiple grooves greater than 20 micrometers long were observed in ECCI, suggesting that the V-grooves do not block dislocation glide. TEM prior to and after coalescence was used to distinguish between dislocation creation driven by growth conditions and coalescence. Finally, strategies to reduce the dislocation density to levels acceptable for solar cells will be discussed.

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