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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
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NASA NTRS2016

Flat Plate Wake Velocity Statistics Obtained With Circular And Elliptic Trailing Edges

The near wake of a flat plate with circular and elliptic trailing edges is investigated with data from direct numerical simulations. The plate length and thickness are the same in both cases. The separating boundary layers are turbulent and statistically identical. Therefore the wake is symmetric in the two cases. The emphasis in this study is on a comparison of the wake-distributions of velocity components, normal intensity and fluctuating shear stress obtained in the two cases.

CFD↗
NASA NTRS2016

Characterizing Cool Giant Planets in Reflected Light

While the James Webb Space Telescope will detect and characterize extrasolar planets by transit and direct imaging, a new generation of telescopes will be required to detect and characterize extrasolar planets by reflected light imaging. NASA's WFIRST space telescope, now in development, will image dozens of cool giant planets at optical wavelengths and will obtain spectra for several of the best and brightest targets. This mission will pave the way for the detection and characterization of terrestrial planets by the planned LUVOIR or HabEx space telescopes. In my presentation I will discuss the challenges that arise in the interpretation of direct imaging data and present the results of our group's effort to develop methods for maximizing the science yield from these planned missions.

James Webb Space Telescope↗
NASA NTRS2016

Multidirectional Cosmic Ray Ion Detector for Deep Space CubeSats

NASA Glenn Research Center has proposed a CubeSat-based instrument to study solar and cosmic ray ions in lunar orbit or deep space. The objective of Solar Proton Anisotropy and Galactic cosmic ray High Energy Transport Instrument (SPAGHETI) is to provide multi-directional ion data to further understand anisotropies in SEP and GCR flux.

Extraterrestrial Radiation↗
NASA NTRS2018

USA Space Debris Environment, Operations, and Research Updates

Space Missions in 2017 Earth Satellite Population Collision Avoidance Maneuvers Post mission Disposal of U.S.A. Spacecraft Space Situational Awareness (SSA) and the Space Debris Sensor (SDS) A total of 86 space launches placed more than 400 spacecraft into Earth orbits during 2017, following the trend of increase over the past decade NASA has established conjunction assessment processes for its human spaceflight and uncrewed spacecraft to avoid accidental collisions with objects tracked by the U.S. Space Surveillance Network - NASA also assists other U.S. government spacecraft owners with conjunction assessments and subsequent maneuvers The ISS has conducted 25 debris collision avoidance maneuvers since 1999 - None in 2016-2017, but an ISS visiting vehicle had one collision avoidance maneuver in 2017 During 2017 NASA executed or assisted in the execution of 21 collision avoidance maneuvers by uncrewed spacecraft - Four maneuvers were conducted to avoid debris from Fengyun-1C - Two maneuvers were conducted to avoid debris from the collision of Cosmos 2251 and Iridium 33 - One maneuver was conducted to avoid the ISS NASA has established conjunction assessment processes for its human spaceflight and uncrewed spacecraft to avoid accidental collisions with objects tracked by the U.S. Space Surveillance Network - NASA also assists other U.S. government spacecraft owners with conjunction assessments and subsequent maneuvers The ISS has conducted 25 debris collision avoidance maneuvers since 1999 - None in 2016-2017, but an ISS visiting vehicle had one collision avoidance maneuver in 2017 During 2017 NASA executed or assisted in the execution of 21 collision avoidance maneuvers by uncrewed spacecraft - Four maneuvers were conducted to avoid debris from Fengyun-1C - Two maneuvers were conducted to avoid debris from the collision of Cosmos 2251 and Iridium 33 The 2014-15 NASA Engineering and Safety Center (NESC) study on the micrometeoroid and orbital debris (MMOD) assessment for the Joint Polar Satellite System (JPSS) provided the following findings - Millimeter-sized orbital debris pose the highest penetration risk to most operational spacecraft in LEO - The most effective means to collect direct measurement data on millimetersized debris above 600 km altitude is to conduct in situ measurements - There is currently no in situ data on such small debris above 600 km altitude Since the orbital debris population follows a power-law size distribution, there are many more millimeter-sized debris than the large tracked objects - Current conjunction assessments and collision avoidance maneuvers against the tracked objects (which are typically 10 cm and larger) only address a small fraction (<1%) of the mission-ending risk from orbital debris To address the millimeter-sized debris data gap above 600 km, NASA has recently developed an innovative in situ measurement instrument - the Space Debris Sensor (SDS) - One maneuver was conducted to avoid the ISS

Liou, J.-C.↗
NASA NTRS2012

Advanced Lithium Ion Venus Explorer (ALIVE)

The COncurrent Multidisciplinary Preliminary Assessment of Space Systems (COMPASS) Team partnered with the Applied Research Laboratory to perform a NASA Innovative Advanced Concepts (NIAC) Program study to evaluate chemical based power systems for keeping a Venus lander alive (power and cooling) and functional for a period of days. The mission class targeted was either a Discovery ($500M) or New Frontiers ($750M to $780M) class mission. Historic Soviet Venus landers have only lasted on the order of 2 hours in the extreme Venus environment:temperatures of 460 degrees Centigrade and pressures of 93 bar. Longer duration missions have been studied using plutonium powered systems to operate and cool landers for up to a year. However, the plutonium load is very large. This NIAC study sought to still provide power and cooling but without the plutonium. Batteries are far too heavy but a system which uses the atmosphere (primarily carbon dioxide) and on on-board fuel to power a power generation and cooling system was sought. The resuling design was the Advanced Long-Life Lander Investigating the Venus Environment (ALIVE) Spacecraft (S/C) which burns lithium (Li) with the CO2 atmosphere to heat a Duplex Stirling to power and cool the lander for a 5-day duration (until the Li is exhausted). While it does not last years a chemical powered system surviving days eliminates the cost associated with utilizing a flyby relay S/C and allows a continuous low data rate direct to earth (DTE) link in this instance from the Ovda Regio of Venus. The five-day collection time provided by the chemical power systems also enables science personnel on earth to interact and retarget science - something not possible with an approximately 2-hour spacecraft lifetime. It also allows for contingency operations directed by the ground (reduced risk). The science package was based on that envisioned by the Venus Intrepid Tessera Lander (VITaL) Decadal Survey Study. The Li Burner within the long duration power system creates approximately 14000 W of heat. This 1300 degree Centigrade heat using Li in the bottom "ballast" tank is melted to liquid by the Venus temperature, drawn into a furnace by a wick and burned with atmospheric CO2. The Li carbonate exhaust is liquid at 1300 degrees Centigrade and being denser than Li drains into the the Li tank and solidifies. Since the exhaust product is a dense liquid no "chimney" is required which conserves the heat for the stirling power convertor. The Duplex Stirling provides about 300 W of power and removes about 300 W of heat from the avionics and heat that leaks into the 1-bar-insulated payload pressure vessel kept at 25 degrees Centigrade. The Na K radiator is run to the top of the drag flap.The ALIVE vehicle is carried to Venus via an Atlas 411 launch vehicle (LV) with a C3 of 7 km2/s2. An Aeroshell, derived from the Genesis mission, enables a direct entry into the atmosphere of Venus (-10 degrees Centigrade, 40 g max) and 6 m/s for landing (44 g) using a drag ring. For surface science and communication, a 100 WRF (WebEx Recording Format), X-Band 0.6-meter pointable DTE (Direct-to-Earth) antenna provides 2 kbps (kilobits per second) to DSN (Deep-Space Network) 34-meter antenna clusters.Table 1.1 summarizes the top-level details of each subsystem that was incorporated into the design. Cost estimates of the ALIVE mission show it at approximately $760M which puts it into the New Frontiers class.The ALIVE landed duration is only limited by the amount of Li which can be carried by the lander. Further studies are needed to investigate how additional mass can be carried, perhaps by a larger launcher and larger aeroshell.

Exploration↗
NASA NTRSDate not supplied

Applying NASA-STD-7009 Standard for Models and Simulations to Surrogate and Other Statistical Models

NASA-STD-7009A, Standard for Models and Simulations, contains a worthy and insightfully-crafted credibility assessment. That set of metrics is intended to accumulate and communicate information that can be critical for users and their customers in evaluating findings due to a model or simulation. Was the model designed for the present use? Is it validated in the domain it’s being applied to? And so on. The standard was originally focused on physics-based models, but it can be applied more generally. It can – and should – be applied to high-impact statistical models, including surrogate models based on larger models and sims and regression models based directly on data. A key issue with many of such models is their relative simplicity compared to most M&S despite their use in high-risk engineering decisions. This report will make a case for using this Standard for a wider class of models, and how it might actually add value in excess of its cost for not only stakeholders, but modelers themselves. A rough example showing compliance for a statistical model is included.

K L Johnson↗
NASA NTRS2020

Estimating the Ultraviolet Emission of M Dwarfs with Exoplanets from Ca ii and Hα

M dwarf stars are excellent candidates around which to search for exoplanets, including temperate, Earth-sized planets. To evaluate the photochemistry of the planetary atmosphere, it is essential to characterize the UV spectral energy distribution of the planet's host star. This wavelength regime is important because molecules in the planetary atmosphere such as oxygen and ozone have highly wavelength-dependent absorption cross sections that peak in the UV (900–3200 Å). We seek to provide a broadly applicable method of estimating the UV emission of an M dwarf, without direct UV data, by identifying a relationship between noncontemporaneous optical and UV observations. Our work uses the largest sample of M dwarf star far- and near-UV observations yet assembled. We evaluate three commonly observed optical chromospheric activity indices—Hα equivalent widths and log(10) L(Hα)/L(bol), and the Mount Wilson Ca ii H&K S and R'(HK) indices—using optical spectra from the HARPS, UVES, and HIRES archives and new HIRES spectra. Archival and new Hubble Space Telescope COS and STIS spectra are used to measure line fluxes for the brightest chromospheric and transition region emission lines between 1200 and 2800 Å. Our results show a correlation between UV emission-line luminosity normalized to the stellar bolometric luminosity and Ca ii R'(HK) with standard deviations of 0.31–0.61 dex (factors of ∼2–4) about the best-fit lines. We also find correlations between normalized UV line luminosity and Hα log(10) L(Hα)/L(bol) and the S index. These relationships allow one to estimate the average UV emission from M0 to M9 dwarfs when UV data are not available.

Katherine Melbourne↗
NASA NTRSDate not supplied

Deep Neural Network Based Unsteady Flamelet Progress Variable Approach in a Supersonic Combustor

Higher dimensional flamelet manifolds are essential in capturing the coupled effects of pressure gradients and unsteady chemical kinetics observed in supersonic combustion applications. Previous studies have validated the feasibility of using deep neural networks as an alternative to computation-ally intensive multidimensional flamelet table storage and lookup. This approach has demonstrated a significant reduction in memory footprint and enabled the use of larger dimensional tabulated manifolds for supersonic combustion in canonical problems. In this study, the Unsteady Flamelet Progress Variable (UFPV)-ANN model implemented in the VULCAN-CFD code is validated by the Burrows-Kurkov supersonic mixing/combustion configuration. The well characterized experimental problem consists of hydrogen injection into a supersonic vitiated crossflow that results in a lifted flame structure. The initial model consists of a 4-dimensional table where the independent variables Z, C, Xst, P are tabulated using an unsteady flamelet code with boundary conditions corresponding to the vitiated air conditions. The results show the development of a lifted flame structure and over-all acceptable agreement with finite-rate chemistry (FRC) simulation and the experimental data. Moreover, direct mapping between the independent variables and the flamelet table is replaced by a deep neural network for significant memory reduction. The results indicate that the UFPV-ANN approach can retrieve the same solution as the memory intensive lookup table approach.

Flamelet↗
NASA NTRSDate not supplied

New Ways of Facilitating Improved Data Discovery and Access for NASA's Suborbital Earth Science Observations

NASA conducts field research in various Earth Science disciplines utilizing airborne and other non-satellite platforms to acquire in situ and remotely sensed observations indicative of physical processes across a range of scales. Field efforts are key in the development and validation of instruments and satellite algorithm refinements. The heterogeneous data, with a range of file formats, scales, and acquisition methods, support research in several science areas. NASA’s archive process assigns data products to discipline-oriented Distributed Active Archive Centers (DAACs) for stewardship. Over time, individual DAACs have developed tools for data browsing and serving disparate user bases. As science becomes more interdisciplinary, researchers need to incorporate observations from multiple campaigns, and multiple DAACs, into their work. Motivated in part by this shifting paradigm of needs, the Catalog of Archived Suborbital Earth Science Investigations (CASEI) was created. CASEI provides a single starting point to browse, search, and discover airborne and field data. Contextual metadata are organized and inter-linked allowing intuitive, integrated exploration across all NASA DAACs. Campaign science objectives, platform and instrument configurations, geographical details, geophysical concepts, and more are tracked in CASEI’s database, facilitating multi-parameter search, browse, and discovery of relevant data products. Researchers are able to directly access associated data products, via DOI links, regardless of the DAAC where they reside. Significant events, key time periods of high science interest within the longer-duration campaign effort, are also indicated and allow for a more efficient identification of critical data subsets. This presentation describes CASEI’s development, intensive metadata curation process, and demonstrates the web interface experience. Initial content metrics and plans for continued maintenance will also be discussed.

metadata↗
NASA NTRS2020

Tidal Effects on the Longitudinal Structures of the Martian Thermosphere and Topside Ionosphere Observed by MAVEN

Longitudinal structures in the Martian thermosphere and topside ionosphere between 150 and 200 km altitudes are studied using in situ electron and neutral measurements from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. Four time intervals are selected for comparison, during which MAVEN sampled similar local time (9.3–10.3 h) and latitude (near 20°S) regions but at different solar longitude positions (two near northern summer solstice, one each at northern vernal and autumnal equinoxes). Persistent and pronounced tidal oscillations characterize the ionosphere and thermosphere, whose longitudinal variations in density are generally in-phase with each other. Our analysis of simultaneous and collocated neutral and electron data provides direct observational evidence for thermosphere-ionosphere coupling through atmospheric tides. We conclude that the ionosphere is subject to modulation by upward-propagating thermal tides, via both tide-induced vertical displacement and photochemical reactions. Atmospheric tides constitute a ubiquitous and significant perturbation source to the ionospheric electron density, up to ∼15% near 200 km.

Xiaohua Fang↗
NASA NTRS2023

Validation of Universal Cryogenic Flow Boiling Correlations in Thermal Desktop for Liquid Helium

Understanding two-phase cryogenic propellant behavior is key to enabling technologies for future spaceflight missions. Developing accurate models of two-phase flow phenomena, particularly flow boiling in the heating configuration is relevant to the propellant transfer process both in microgravity and on other planetary surfaces. Currently there is a need for more accurate, direct cryogenic data anchored models for various boiling phenomena. Recently, universal correlations for cryogens flowing in heated tubes have been developed for a wide variety of fluids, thermodynamic conditions, and various regimes across the boiling curve, and have been patched to provide a smooth, continuous predictive curve. This paper demonstrates how these correlations have been ported into Thermal Desktop to improve predictive performance. To test the validity of the new correlations, Thermal Desktop is validated against a historical dataset of flow boiling experiments in the heating configuration using liquid helium. Based on results, the new correlations show a substantial improvement over the original built-in flow boiling correlations in Thermal Desktop in predicting the wall temperature as a function of preponderant parameters for this quantum fluid.

cryogenic propellant transfer↗
NASA NTRSDate not supplied

Validation of Universal Cryogenic Flow Boiling Correlations in Thermal Desktop for Liquid Helium

Understanding two-phase cryogenic propellant behavior is key to enabling technologies for future spaceflight missions. Developing accurate models of two-phase flow phenomena, particularly in the current work, flow boiling in the heating configuration, is relevant to the propellant transfer process both in 1-g and microgravity. Currently there is a need for more accurate, direct cryogenic data anchored models for various boiling phenomena. Recently, universal correlations for cryogens flowing in heated tubes have been developed for a wide variety of fluids, thermodynamic conditions, and various regimes across the boiling curve, and have been patched to provide a smooth, continuous predictive curve. This paper describes implementation and validation of these correlations into Thermal Desktop to improve predictive performance, with a focus on liquid helium. Results from Thermal Desktop using both the built-in and new correlations are validated against a historical dataset of flow boiling experiments in the heating configuration using liquid helium. Based on results, the new correlations show a substantial improvement over the original built-in flow boiling correlations in Thermal Desktop in predicting the wall temperature as a function of preponderant parameters for this quantum fluid at temperatures greater than the lambda temperature, T λ = 2.17K.

cryogenic propellant transfer↗
NASA NTRSDate not supplied

Applications and Development Work for Digital Image Correlation Using High Speed Cameras

NASA, Army, and industry partners are working to advance optical measurement techniques used in highly dynamic rocket engine and missile test environments. This allows for direct component data collection during test and flight environments, significantly reduced analysis time, and associated cost savings. Digital Image Correlation (DIC) uses calibrated stereo cameras to collect three-dimensional (3-D) displacements, strains, and acceleration data by referencing a stochastic speckle pattern applied to the test object. These optical measurement techniques provide significantly improved data resulting in better performance predictions, model validation, and information about components during hot-fire tests and test flights.

Rachel Paden↗
NASA NTRS2019

Directional limits on persistent gravitational waves using data from Advanced LIGO’s first two observing runs

We perform an unmodeled search for persistent, directional gravitational wave (GW) sources using data from the first and second observing runs of Advanced LIGO. We do not find evidence for any GW signals. We place limits on the broadband GW flux emitted at 25 Hz from point sources with a power law spectrum at F(α;Θ) < (0.05–25) × 10^(−8) erg/sq. cmsHz and the (normalized) energy density spectrum in GWs at 25 Hz from extended sources at Ω(α)(Θ) < (0.19–2.89) × 10^(−8) per sr where α is the spectral index of the energy density spectrum. These represent improvements of 2.5–3× over previous limits. We also consider point sources emitting GWs at a single frequency, targeting the directions of Sco X-1, SN 1987A, and the Galactic center. The best upper limits on the strain amplitude of a potential source in these three directions range from h(0) < (3.6–4.7) × 10^(−25), 1.5× better than previous limits set with the same analysis method. We also report on a marginally significant outlier at 36.06 Hz. This outlier is not consistent with a persistent gravitational-wave source as its significance diminishes when combining all of the available data.

B. P. Abbott↗
NASA NTRS1982

Sources of lunar magnetic anomalies and their bulk directions of magnetization - Additional evidence from Apollo orbital data

A relatively high-amplitude magnetic anomaly directly detected with the Apollo 15 subsatellite magnetometer and centered near the crater Gerasimovich on the southeastern lunar far side is found to correlate with the location of a conspicuous Reiner Gamma-type swirl marking visible on a Zond 8 photograph. Examinations of available direct and indirect orbital magnetics measurements demonstrate that most strong anomalies occur in areas where morphologically similar markings are concentrated. Even though photogeologic studies indicate an impact-related origin for the swirls, both the swirls and their associated strong anomalies tend to exist preferentially in or near areas that have been seismically modified. Modeling of improved vector magnetic anomaly maps is used to infer 28 independent bulk directions of magnetization for relatively strong and isolated lunar magnetic anomaly sources.

Hood, L. L.↗
NASA NTRS2014

Interplanetary and Interstellar Dust Observed by the Wind/WAVES Electric Field Instrument

Observations of hypervelocity dust particles impacting the Wind spacecraft are reported here for the first time using data from the WindWAVES electric field instrument. A unique combination of rotating spacecraft, amplitude-triggered high-cadence waveform collection, and electric field antenna configuration allow the first direct determination of dust impact direction by any spacecraft using electric field data. Dust flux and impact direction data indicate that the observed dust is approximately micron-sized with both interplanetary and interstellar populations. Nanometer radius dust is not detected by Wind during times when nanometer dust is observed on the STEREO spacecraft and both spacecraft are in close proximity. Determined impact directions suggest that interplanetary dust detected by electric field instruments at 1 AU is dominated by particles on bound trajectories crossing Earths orbit, rather than dust with hyperbolic orbits.

Wind spacecraft↗