Global maps of maximum bottom particle concentration, benthic nepheloid layer thickness, and integrated particle mass in benthic nepheloid layers (BNL) based on 2412 global profiles collected using the Lamont Thorndike nephelometer from 1964-1984 are compared with maps of those same properties compiled from 6,392 global profiles measured by transmissometers from 1979 to 2016. Outputs from both instruments were converted to particulate matter concentration (PM). We present here a visual global comparison of the location and intensity of BNLs measured with these two independent instruments over slightly overlapping decadal time periods and combine the data sets in order to expand the time scale of global in situ measurements of BNLs, and to gain insight about the factors creating/sustaining BNLs. The similarity between general locations of high and low particle concentration BNLs during the two time periods indicates that the driving forces of erosion and resuspension of bottom sediments are spatially persistent during recent decadal time spans, though in areas of strong BNLs, intensity is highly episodic. Topography and well-developed current systems play a role. These maps can be used to better understand deep ocean sediment dynamics, linkage with upper ocean dynamics, the potential for scavenging of adsorption-prone elements near the seafloor, and provide a comprehensive comparison of these data sets on a global scale. During both time periods, BNLs are weak or absent in most of the Pacific, Indian, and Atlantic basins away from continental margins. High surface eddy kinetic energy is associated with the Kuroshio Current east of Japan. Both data sets show weak BNLs south of the Kuroshio, but no transmissometer data have been collected beneath the Kuroshio itself. Sparse nephelometer data show moderate BNLs just north of the Kuroshio Extension, but with much lower concentrations than beneath the Gulf Stream. Strong BNLs are found in areas where eddy kinetic energy in overlying waters, mean kinetic energy near bottom, and energy dissipation within the bottom boundary layer are high. Areas of strongest BNLs include the Western North Atlantic, Argentine Basin, areas around South Africa tied to the Agulhas Current region, and somewhat random locations in the Antarctic Circumpolar Current of the Southern Ocean.

The leading paradigm for rift initiation suggests “magma-assisted (wet)” rifting is required to weaken strong lithosphere such that only small tectonic stresses are needed for rupture to occur. However, there is no surface expression of magma along the 300 km long Albertine-Rhino Graben (except at its southernmost tip within the Tore Ankole Volcanic Field), which is the northernmost rift in the Western Branch of the East African Rift System. The two prevailing models explaining magma-poor rifting are: 1) Melt is present at depth weakening the lithosphere, but it has not reached the surface or 2) far-field forces driving extension are accommodated along weak pre-existing structures without melt at depth. The goal of this study is to test the hypothesis that melt is generated below the Albertine-Rhino Graben from Lithospheric Modulated Convection (LMC) using the 3D finite element code ASPECT. We develop a regional model of a rigid lithosphere and an underlying convecting sublithospheric mantle that has dimensions 1000 by 1000 by 660 km along latitude, longitude, and depth, respectively. We solve the Stokes equations using the extended Boussinesq approximation for an incompressible fluid which considers the effects of adiabatic heating and frictional heating. We include latent heating such that we can test for melt generation in the sublithospheric mantle from LMC. Using LITHO1.0 as the base of our lithosphere, our preliminary results suggest melt could be generated beneath the Albertine-Rhino graben given a mantle potential temperature of 1800 K. These early results indicate LMC can generate melt beneath the northernmost Western branch of the East African Rift System.

Accurate photoionization rates are vital for the study and understanding of ionospheres and may account for the discrepancy in electron densities and mismatched altitude profiles of current E-region models. The underestimation of electron density profiles could be mitigated by high-resolution cross sections that preserve autoionization lines which allow solar photons to leak through to lower altitudes. We present new ionization rates calculated with high-resolution (0.001 nm) O and N2 photoionization and electron impact cross sections, and a high-resolution solar spectrum as inputs to CPI’s Atmospheric Ultraviolet Radiance Integrated Code [AURIC, Strickland et al., 1999]. The new electron impact cross sections show little structure and have minimal effect on calculations of ionization rates. Results from AURIC with updated O and N2 cross sections indicate increased production rates up to ~40% in the E-region, specifically between 100–115 km. Likewise, production rates determined using the ionospheric photoionization rate code from Meier et al. [2007] also illustrate an increase in the O and N2 production rates (typically of more than 10%) when using the newly calculated cross sections. Additionally, we find that O and N2 dominate the volume production rates above 130 km while O2 is expected to be the main contributor from 95–130 km. AURIC model results that use the default data and model results with the new O and N2 cross sections both track very well with electron density profiles determined from Arecibo ISR observations. AURIC model results using the new cross section calculations are in better agreement with Arecibo observations at higher altitudes. Our current findings indicate that O2 plays a dominant role in photoionization production rates in the E-region. Therefore it is crucial to update ab initio ionospheric models with high-resolution photoionization cross sections.

The earth’s crust is a leaky geofluid system where surface trace gas emissions relate to open migration pathways and the presence of subsurface source(s). Seismic activity can open sealed migration pathways leading to trace gas emissions from the surface intersection of the active fault, which may not relate to observable surface fault rupture or offset. After the M7.1 Ridgecrest earthquake, we collected mobile surface trace gas and meteorology data with AMOG (AutoMObile trace Gas) Surveyor, a mobile atmospheric chemistry and meteorology lab, in the Death Valley Park and Searles Valley within 24 hours of the quake, the following week, and after several weeks with air samples also were collected for detailed later laboratory analysis. We found widespread highly elevated CO2 emissions along Panamint Valley including overall elevated SO2 and H2S with strong enhancements around Manly Pass, where aftershocks occurred at the northern edge of the Slate Range and along a trend parallel to Water Canyon. This is in contrast to AMOG data collected in Death and Panamint Valleys in 2014, where concentrations were typical of California desert levels–near ambient and uniform. Significant sulfur trace gas emissions were discovered escaping from the rim of Ubehebe Volcano, last active ~2500 B.P., 115-km north of the Slate Range. Faults appear to play an important role in these geogas emissions, activated by the major earthquake and aftershocks. Further investigations are planned to characterize the system’s return towards quiescence.

Stable isotope geochemistry of terrestrial carbonates provides important opportunities to answer questions about climates, environments, and ecosystems both in the present day and the geologic past. Here we present a case study from the Cretaceous Newark Canyon Formation (NCF) type section (~98–113 Ma), where we explore how climate and depositional settings influence the stable isotope record in highly variable lacustrine and palustrine carbonates. The NCF was deposited within the hinterland of the Sevier orogenic belt and allows us to examine how North American terrestrial climate changed during the mid-Cretaceous, a time of potentially significant regional surface uplift and increasing global temperatures related to the Cretaceous Thermal Maximum (Di Fiori et al., 2020; Huber et al., 2018). In this study, we find substantial inter- and intra-facies heterogeneity, despite having formed in the same overall climate setting, highlighting the differences between lacustrine and palustrine environments. Stable carbon, oxygen, and clumped isotopes (δ13C, δ18Ocarbonate, and Δ47) paired with optical and cathodoluminescence petrography from along-strike lateral and vertical stratigraphic sections show significant isotopic variability between and within seven carbonate facies (Fetrow et al., 2020). Palustrine deposition is interpreted to have occurred along a spectrum of shallow water depths preserved in two key palustrine sub-facies endmembers – shallower mottled micrite and deeper pebbly, peloid-rich micrite. These record mean Δ47 temperatures of 51ºC and 44°C, respectively. The mottled micrite has heavier calculated δ18O of formation water (δ18Owater) values indicating increased evaporative enrichment, which suggests more intense desiccation during deposition. Lacustrine sediments preserved in laminated biomicrite to massive micrite have mean Δ47 temperatures of 50ºC and 37°C, respectively. Elevated temperatures and δ13C, δ18Ocarb, and δ18Owater values more similar to values from NCF secondary spar veins indicate that the biomicrite sub-facies underwent diagenetic alteration. We will discuss the implications of these results for the NCF and the Cretaceous western USA paleoclimate record, as well as general lessons learned for interpreting mixed terrestrial carbonate facies records.

Documentation of primitive terrestrial life signatures and the methods used to characterize them will be relevant to identify signatures of biological origin at the surface of Mars. In this respect, fossils of chemolithotrophic microorganisms found in ancient volcanic rocks on Earth are used as analogues for the kinds of microorganisms that could be found on Mars. Indeed, chemolithotrophs are the ancient forms of life thought to inhabit the first habitats on Earth and potentially on Mars when the two planets had similar conditions in their early history, i.e. an atmosphere, geological activity and enough liquid water in specific habitable localities for a prolonged period of time.

The story the Antarctic Core Collection’s (ACC) transition from Florida State University (FSU) to Oregon State University (OSU) is one of the largest-scale data rescue efforts in recent history. The ACC is the world’s largest collection of seafloor sediment samples from the Southern Ocean. The collection was officially established in 1963 as the US Antarctic Program took shape. For the next fifty years, the collection grew to represent the scientific discoveries of over one-hundred and twenty research cruises and expeditions around Antarctica. FSU hosted the irreplaceable collection at its Antarctic Research Facility, an iconic lab in the center of campus. In 2016, the university chose not to renew its contract for supporting the facility. Recognizing the value and potential of the collection, the National Science Foundation began a search for another university to host these important samples and enable future research. In 2017, OSU’s Marine and Geology Repository (OSU-MGR) initiated a plan to relocate this historic collection of over eighteen kilometers of core samples from Tallahassee, FL to Corvallis, OR. The project began by planning and constructing a state-of-the-art facility with temperature-controlled space to house the next fifty years of coring expeditions to the Southern Oceans and beyond. In the summer of 2018, the ACC was carefully packaged, digitally inventoried, and shipped to OSU. In this process, the OSU-MGR staff have worked to improve metadata records to build an effective modern inventory of the ACC using new digital collection management techniques, including QR coded labels and scanners. These metadata are managed on tablets with the OSU-MGR App and indexed in an Elasticsearch cluster to streamline the repository’s workflows and to display summary statistics. Current and future curation projects will comply with FAIR data principles, with the goal of making all OSU-MGR collections and associated datasets more easily discoverable online.

We present our latest understanding of the processes that shape the spatial distributions of energetic electrons trapped in the magnetospheres of Uranus (L < 15) and Neptune (L < 25). To determine what controls the energy and spatial distributions throughout the different magnetospheres, we compute the time evolution of particle distributions with the help of a diffusion theory particle transport code that solves the governing 3-D Fokker-Planck equation. Different mechanisms of particle loss, source and transport are numerically examined. Our theoretical modeling is guided by the analysis of particle, field and wave data collected during Voyager 2’s flyby of Uranus in January 1986 and at Neptune in August 1989. Our preliminary data-model comparison results at Uranus show that adiabatic transport cannot explain the radial and angular features of warm to ultra-relativistic electron populations within the ~1-15 L region. Our simulation results also suggest that, with absence of loss mechanisms inside L = 15, energetic and radiation-belt electron populations would be higher by 1-3 orders of magnitude in intensity close to the planet (L ~ 1-8). Particularly, our results confirm that moon sweeping effect is a significant loss mechanism at Uranus. Nonetheless, other radial, energy and pitch-angle dependent mechanisms seem to be missing to explain the in-situ data. We will thus present our ongoing effort to examine the role of - for instance, Uranus’ rings system, atomic hydrogen corona and wave activity inward of L ~ 8-10 to improve our modeling of Uranus’ electron populations between L values of 1 and 15. Our first physics-based model of energetic electrons at Neptune will be presented, emphasizing first the role of radial transport and moon sweeping effect for the 1-25 L region before investigating new processes. Our models developed for Uranus and Neptune are based on the theoretical modeling of electron distributions at Saturn, which included the modeling of radial transport and interactions of electrons with Saturn’s dust/neutral/plasma environments and waves, as well as particle sources from high-latitudes, interchange injections, and outer magnetospheric region. Comparisons between the distributions of electron populations at Gas and Ice Giant systems will be discussed. Data analysis, theoretical modeling, and numerical computations for Uranus and Neptune are carried out by adapting the Kronian modeling tools developed at Southwest Research Institute to the Ice Giants environment. Key data analysis, theoretical modeling, and numerical computational tasks for Saturn were carried out at Southwest Research Institute under NASA GSFC grant 80NSSC18K1100.

Holistic assessment of fruit quality is an essential component of producing Strawberry varieties that will succeed in the marketplace and improve consumer satisfaction. However, several key quantitative traits are notoriously slow and expensive to assess using standard procedures, namely acidity and aroma, which require titration and gas chromatography and mass spectroscopy compared to others: brix, anthocyanins, and vitamin C, which are measured by refractometer and parallelized plate reader assays. Scaling up evaluations for acidity and aroma has been difficult as the techniques require 5 and 40 mins/sample, respectively, and sample preparation is equally intense, requiring multiple trained hands working for 10-hour sessions to create the sample series for 100 entries. We evaluated the ability (R 2 , RMSE) of a handheld near infrared (NIR) spectrometer, measuring 125 wavelengths between 800 and 1600 nm, and an electronic nose, measuring the reaction of 32 electrochemical sensors that respond to various compounds in gas samples, on 4,000 diverse strawberry accessions to determine if the 5 and 40 min/sample assays can be replaced with a 1 (0.33%) sec/sample (NIR) and 2 (5%) min/sample (E-nose) assay that require no additional sample prep. We also assess the NIR's ability to predict brix, anthocyanins, and vitamin C. With these two sensors, we will be able to increase the scale of early generation evaluation from hundreds to thousands of samples in early generations, produce full datasets prior to deadlines in the breeding program, and make more reliable genetic gains for quality traits affecting marketability and consumer acceptance.

The SEIS seismometer deployed at the surface of Mars in the framework of the NASA-InSight mission has been continuously recording the ground motion at Elysium Planitia for more than one martian year. In this work, we investigate the seasonal variation of the near surface properties using both background vibrations and a particular class of high-frequency seismic events. We present measurements of relative velocity changes over one martian year and show that they can be modeled by a thermoelastic response of the Martian regolith. Several families of high-frequency seismic multiplets have been observed at various periods of the martian year. These events exhibit repeatable waveforms with an emergent character and a coda that is likely composed of scattered waves. Taking advantage of these properties, we use coda waves interferometry to measure relative travel-time changes as a function of the date of occurrence of the quakes. While in some families a stretching of the coda waveform is clearly observed, in other families we observe either no variation or a clear contraction of the waveform. Measurements of velocity changes from the analysis of background vibrations above 5Hz are consistent with the results from coda wave interferometry. We identify a frequency band structure in the power spectral density, that can be tracked over hundreds of days. This band structure is the equivalent in the frequency domain of an autocorrelogram and can be efficiently used to measure relative travel-time changes as a function of frequency. The observed velocity changes can be adequately modeled by the thermoelastic response of the regolith to the time-dependent incident solar flux at the seasonal scale. In particular, the model captures the time delay between the surface temperature variations and the velocity changes in the sub-surface. Our observations could serve as a basis for a joint inversion of the seismic and thermal properties in the first meters below InSIght.

The present study tries to assess and mitigate the geohazard-prone area in Barora Coalfield using geophysical methods. Barora being, a significant subsidiary of the Jharia coalfield, plays a crucial role in India's growing energy demand. The study area is affected by coal fire in the subsurface as illustrated by its thermal images. To evaluate subsurface conditions, magnetic data was taken initially. The magnetic data was first then reduced-to-pole and further centroid method was applied to determine the curie depth. The average curie depth was found to be approximately 10.74±0.9 meters, indicating active coal fires beneath this depth. Furthermore, using the multichannel analysis of surface wave (MASW) method, a significant change in velocity gradient was observed at a depth of around 11 meters, indicating variations in the velocity layers. To gain a comprehensive understanding of the subsurface, the ambient noise tomography method was employed. This revealed the presence of a coal seam at an approximate depth of 30 meters and also indicated the existence of abandoned underground galleries below 40 meters depth. Appending the dispersion curve from both seismic methods, we determined that the active coal seam at approximately 30 meters depth extended around 15 meters and was significantly affected by coal fires. The outcomes established the presence of underground galleries, oriented in the NE-SW direction, leading toward the SouthEastern railways which might be prone to subsidence.

Lava tubes can offer protection for human crews and their equipment on other solar system bodies, in particular from radiation threats and extreme surface temperatures. Developing strategies to survey regions of other terrestrial bodies (such as the Moon or Mars) for tubes suitable for potential habitation will likely become an important part in planning future space exploration projects. A variety of surface geophysical techniques, such as ground penetrating radar (GPR) have the potential to help recognize and map tubes. GPR shows promise for providing high resolution information on tube geometries. To investigate GPR’s capacity and limitations, we use GPR, as well as comparative methods of seismic and magnetic surveys, in conjunction with LiDAR mapping of tube interiors at the Lava Beds National Monument (LBNM) in California, USA. LBNM offers a wide variety of tube geometries and textures. We have collected 2D GPR profiles and small 3D GPR grids (of parallel 2D lines) with antenna frequencies of 100 and 200 MHz on four lava tubes with different geometries, textures and at different depths. Challenges in recovering tube geometries include wave scattering in fractured rock covering tubes, irregular and “drippy” ceilings and walls, and blocky floors. Our primary results show that the top of the LBNM tubes can generally be resolved in the GPR data, while resolving the bottom is more challenging. The utility of various GPR processing techniques can be directly assessed by comparing resolved GPR images against the LiDAR-measured tube geometries.

To prevent serious problems occurring in abandoned mines such as ground subsidence, it is commonly carried out to fill cavities with some materials. During or after the cavity-filling process, we need to monitor distribution of filling materials in abandoned mines. Various geophysical methods, such as microgravity, electrical resistivity, ground penetrating radar, and seismic methods, have been used to describe abandoned mines themselves or to monitor distribution of filling materials. Microgravity, electrical resistivity, ground penetrating radar, and microseismic methods can be used to detect cavities, but may have some limitation in monitoring material distributions. In this study, we apply the seismic reflection method to image distribution of filling materials in near-surface abandoned mines. As the imaging methods, we use full waveform inversion and reverse time migration. In addition, we apply seismic interferometry to obtain better results. The full waveform inversion and reverse time migration methods are applied to four models which can mainly appear in abandoned mines. Through numerical examples, we investigate feasibility of seismic reflection method for describing filling material distribution in abandoned mine. Acknowledgements This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2017R1A2B4002031) and by the project funded by the Ministry of Oceans and Fisheries, Korea (D11603317H480000112).

Like most NSF-funded Research Experience for Undergraduates (REU) programs, the REU on Sustainable Land and Water Resources (REU SLAWR) had to choose between a virtual experience in summer 2020, or cancellation of the program due to the Covid19 pandemic. The REU SLAWR was restructured into a modular online program designed to meet the same program goals that have shaped the REU SLAWR over the past 11 years. Using program evaluations from 2011-2019, the authors will compare the results from 2020 to build knowledge on how the REU experience in 2020 was differently structured to meet the need for a virtual program, the impact this had on participant and mentor outcomes, and what can be learned for future REU programs. This provides valuable information for creating accessibility to the REU experience. The REU usually takes place at three locations (Salish Kootenai College, MT; at the Univ. of Minnesota in Mpls. and Duluth, MN). The program is centered on tribally-focused Community-based Participatory Research (CBPR), and is a place-based REU. The REU SLAWR has always incorporated a virtual experience designed to create cross-team socialization, community-building, and widen participants’ interest and knowledge about projects incorporating tribal CBPR. Summer 2020 immersed students, mentors, and tribal partners in a virtual learning environment. The PIs explored new methods for running an REU with virtual technology that will be incorporated in future programs for richer cross-team collaboration. A focus of the REU SLAWR has been to increase participants’ abilities to work on diverse teams. Collaborating virtually across distances is a skill all researchers need. Training in this can benefit next-generation researchers and STEM workers. One aspect of concern and interest is the impact of redesigning the research projects to make them possible to conduct in a virtual space. The projects were fundamentally different than previous years, with many focusing on using pre-existing data. While there were negative impacts in some aspects of building research skills (i.e., little exposure to field or lab work), other aspects (i.e., computational modeling, communicating science) showed gains. The authors explore both the limits and possibilities inherent in virtual collaboration in research for undergraduate students.

Terrestrial hot springs have existed throughout Earth’s history and house some of the most ancient evidence of life on our planet. These settings are known for their high habitability and preservation potential, and are extensively studied as analog environments since hot spring deposits are thought to exist on the surface of Mars. Hot spring water commonly precipitates silica that coats microbial life dwelling in the hot spring outflow streams. This process can entomb microorganisms and preserve microbial remains over long timescales and with high morphological fidelity. Here we present research carried out on modern and sub-recent remains of microbial filaments from amorphous (unaltered) silica deposits in Yellowstone National Park. This work suggests that various elements sequestered by hot spring-dwelling organisms during life are preserved in microbial remains and persist over > 10,000 years. We also present findings from microfossils preserved in mid-Paleozoic terrestrial hot spring deposits which also show sequestrations of select elements in microfossil remains, suggesting that certain elements may persist even after several hundred million years and substantial host rock alteration. These elemental concentrations may be indicative of metabolic functioning during life and have application as biosignatures. Recent developments in analytical instrumentation now allow for even extremely low trace elemental abundances to be detected and mapped, regardless of sample complexity. This work is especially relevant to the search for life on Mars, as evidence of impact-induced hydrothermal activity may exist near the rim of Jezero Crater and may be sampled by the Perseverance rover. As a primary objective of the Mars 2020 mission is to search for evidence of past life on Mars, we suggest the application of this analytical technique to be valuable for potential samples returned to Earth by future Mars Sample Return missions. Distribution Statement A. Approved for public release: distribution unlimited.

Marine aggregates are ubiquitous particles formed from the accretion of smaller biogenic and non-biogenic components. Visible aggregates, known as marine snow, are typically in the 0.5 to few mm size range. Aggregates are well recognised as hotspot of microbial and planktonic activities. Aggregates formation is an important pathway for transferring materials and carbon flux from surface to the deep ocean. Because aggregate sinking velocity and carbon mass content is size dependent, understanding the physical mechanism controlling aggregate size distribution is fundamental to determining the biological carbon pump efficiency. Turbulence is a physical mechanism in the aggregates formation and destruction. However, the relative roles of turbulence in aggregates formation and destruction have not been fully tested in observational studies. In this study, we analysed simultaneous in-situ observations of turbulence and aggregate in the various aquatic systems. A microstructure profiler, TurboMAP-L, was used to collect shear data and a digital still logger camera was used to collect images of aggregates. Digital images were subsequently used to determine aggregates abundances and size distributions. Direct comparison of turbulence intensity and aggregate size distributions show that turbulence below 𝜀=10-6[W/kg] enhances aggregation, increasing average particle size; greater turbulence causes particle breakup, limiting the average maximum aggregate size and decreasing the slopes of size distributions. This indicates the role of turbulence controlling aggregate size distributions. We also present fluorescence data collected by TurboMAP-L and focus on difference of aggregates size distributions among different aquatic systems.

The Undergraduate Student Instrumentation Project (USIP) was a NASA program to engage undergraduate students in rigorous scientific research, for the purposes of innovation and developing the next generation of professionals in space research. The program is student led and executed from initial ideation of research objectives to the design and deployment of scientific payloads. The University of Houston was selected twice to participate in the USIP programs. The first program (USIP_UH I) ran from 2013 to 2016. USIP_UH II ran from 2016 to 2019. USIP_UH I (USIP_UH II) at the University of Houston was composed of eight (seven) research teams developing six (seven), distinct, balloon-based scientific instruments. This project was a for-credit course two years in duration. The program has been so successful in terms of improved student career outcomes the University has decided to continue the project with purely local funding. The pandemic has produced a substantial instructional challenge since this project is a lab class! The virtual classroom that we designed to meet this need provides tools for ongoing collaboration, revisions, storage, project planning, systems engineering, and a tool to request immediate feedback from faculty and fellow researchers. Additionally, the classroom provides an ongoing place to store data from different students for many years. New students can use this continuity in a consistent and secure way. We also provided tools for conferencing and communication. A combination of several tools were selected and customized to meet this need. These tools include Google Classroom, Microsoft Teams, Slack, Git, Groupme, and Zoom.

Single-aliquot (U-Th)/He dating of iron-oxides requires less mass and has a higher spatial resolution than the two-aliquot approach, and is, therefore, a more reliable tool for quantifying the timescales of weathering processes, fault activity, and the development of soils and surfaces. Highly helium-retentive hematite samples must be heated to 1000-1100 °C to completely degas He, but we show that U is lost progressively during laser-heating starting at ~900 °C, with major U-loss at ~980 °C and complete U-loss at 1050-1100 °C. This partial or complete loss of U leads to incorrect (U-Th)/He ages that appear older than the true ages. We performed a series of heating tests on hematite and goethite aliquots with independently determined (U-Th)/He ages of 10-1761 Ma in which the helium release was determined by isotope-dilution mass spectrometry and phase change was monitored by infrared spectroscopy. As hematite is heated, reduction of Fe3+ causes a phase change to magnetite and then to elemental Fe. We correlate the onset of U-loss to the phase change from hematite to magnetite. By raising the temperature of this phase transition using a high oxygen partial pressure (pO2) in the sample chamber during laser-heating, we show that the onset temperature of U-loss is equally raised. Samples can therefore be safely degassed at higher temperatures without any detectable U-loss. In our implementation of this technique, the O2 in the sample chamber is being withdrawn from a tank using a pipette and it is being released before and captured after the degassing process on activated charcoal in a cold finger with a movable LN2 Dewar flask. We describe the automation of this process for routine degassing of hematite samples. We show that an average age calculated on a reference hematite sample from replicate aliquots (n=12), which were analyzed using this procedure, has a relative uncertainty of 2% (1σ), and is within uncertainty of the previously measured two-aliquot age. We suggest this high-pO2 degassing procedure as a way to precisely and reproducibly determine single-aliquot hematite and goethite (U-Th)/He ages.