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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 829 records · Page 46

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NASA NTRS1990

Long-term compression effects on elastomeric O-ring behavior

This paper discusses the results of testing performed on elastomeric seal materials that had been under compression for extended periods of time. Elastomeric seals used in the Space Shuttle redesigned solid rocket motors can experience compression times of up to six months. These seals must be capable of sealing internal motor pressure upon ignition. The tests described herein were performed in order to verify that the seals, which had experienced long-term compression could seal throughout motor operation. Testing was divided into two phases: (1) dynamic high pressure testing, and (2) resiliency testing. Dynamic testing was performed using specialized test fixtures that allowed simulation of the field joint movements during initial motor operation along with high pressure gas. Resiliency testing was performed using specialized test fixtures that also simulated field joint movements and also had the ability to measure the sealing force of the O-ring. Results from all testing indicated that the current elastomeric seals used in the redesigned solid rocket motors will seal during motor operations in the currently defined launch environments.

Clinton, R. G.↗

NASA NTRS1990

A search for long-term periodicities in large earthquakes of southern and coastal central California

It has been occasionally suggested that large earthquakes may follow the 8.85-year and 18.6-year lunar-solar tidal cycles and possibly the approximately 11-year solar activity cycle. From a new study of earthquakes with magnitudes greater than 5.5 in southern and coastal central California during the years 1855-1983, it is concluded that, at least in this selected area of the world, no statistically significant long-term periodicities in earthquake frequency occur. The sample size used is about twice that used in comparable earlier studies of this region, which concentrated on large earthquakes.

Stothers, Richard B.↗

NASA NTRS2002

In-Vessel Composting of Simulated Long-Term Missions Space-Related Solid Wastes

Reduction and stabilization of solid wastes generated during space missions is a major concern for the Advanced Life Support - Resource Recovery program at the NASA, Kennedy Space Center. Solid wastes provide substrates for pathogen proliferation, produce strong odor, and increase storage requirements during space missions. A five periods experiment was conducted to evaluate the Space Operation Bioconverter (SOB), an in vessel composting system, as a biological processing technology to reduce and stabilize simulated long-term missions space related solid-wastes (SRSW). For all periods, SRSW were sorted into components with fast (FBD) and slow (SBD) biodegradability. Uneaten food and plastic were used as a major FBD and SBD components, respectively. Compost temperature (C), CO2 production (%), mass reduction (%), and final pH were utilized as criteria to determine compost quality. In period 1, SOB was loaded with a 55% FBD: 45% SBD mixture and was allowed to compost for 7 days. An eleven day second composting period was conducted loading the SOB with 45% pre-composted SRSW and 55% FBD. Period 3 and 4 evaluated the use of styrofoam as a bulking agent and the substitution of regular by degradable plastic on the composting characteristics of SRSW, respectively. The use of ceramic as a bulking agent and the relationship between initial FBD mass and heat production was investigated in period 5. Composting SRSW resulted in an acidic fermentation with a minor increase in compost temperature, low CO2 production, and slightly mass reduction. Addition of styrofoam as a bulking agent and substitution of regular by biodegradable plastic improved the composting characteristics of SRSW, as evidenced by higher pH, CO2 production, compost temperature and mass reduction. Ceramic as a bulking agent and increase the initial FBD mass (4.4 kg) did not improve the composting process. In summary, the SOB is a potential biological technology for reduction and stabilization of mission space-related solid wastes. However, the success of the composting process may depend of the physical characteristics (particle size, porosity, structure, texture) of the SBD components which would require pre-processing of solid wastes before placing them in the SOB.

Rodriguez-Carias, Abner A.↗

NASA NTRS1979

Long-term studies with the Ariel 5 ASM. I - Hercules X-1, Vela X-1, and Centaurus X-3

Twelve hundred days of 3-6 keV X-ray data from Her X-1, Vela X-1, and Cen X-3 accumulated with the Ariel 5 All-Sky Monitor are interrogated. The binary periodicities of all three can be clearly observed, as can the 35 day variation of Her X-1, for which we can refine the period to 34.875 plus or minus 0.030 days. No such longer-term periodicity less than 200 days is observed from Vela X-1. The 26.6 days low-state recurrence period for Cen X-3 is not observed, but a 43.0 day candidate periodicity is found which may be consistent with the precession of an accretion disk in that system. The present results are illustrative of the long-term studies which can be performed on approximately 50 sources over a temporal base which will ultimately extend to at least 1800 days.

Holt, S. S.↗

NASA NTRS2015

Long-Term Cryogenic Propellant Storage for the TOPS Mission

Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LOX) can dramatically enhance NASAs ability to explore the solar system because of their superior specific impulse (Isp) capability. Although these cryogenic propellants can be challenging to manage and store, they allow significant mass advantages over traditional hypergolic propulsion systems and are therefore technically enabling for many planetary science missions. New cryogenic storage techniques such as subcooling and the use of advanced insulation and low thermal conductivity support structures will allow for the long term storage and use of cryogenic propellants for solar system exploration and hence allow NASA to deliver more payloads to targets of interest, launch on smaller and less expensive launch vehicles, or both. Employing cryogenic propellants will allow NASA to perform missions to planetary destinations that would not be possible with the use of traditional hypergolic propellants. These new cryogenic storage technologies were implemented in a design study for the Titan Orbiter Polar Surveyor (TOPS) mission, with LH2 and LOX as propellants, and the resulting spacecraft design was able to achieve a 43 launch mass reduction over a TOPS mission, that utilized a conventional hypergolic propulsion system with mono-methyl hydrazine (MMH) and nitrogen tetroxide (NTO) propellants. This paper describes the cryogenic propellant storage design for the TOPS mission and demonstrates how these cryogenic propellants are stored passively for a decade-long Titan mission.

Cryogenic Propellant Storage↗

DOE OSTI2020

Consequences of long-term water exposure for bulk crystal structure and surface composition/chemistry of nickel-rich layered oxide materials for Li-ion batteries

Water exposure of layered nickel-rich transition metal oxide electrodes, widely used in high-energy lithium-ion batteries, has detrimental effects on the electrochemical performance, which complicates electrode handling and prevents implementation of environmentally benign aqueous processing procedures. Elucidating the degradation mechanisms in play may help rationally mitigate/circumvent key challenges. Here, the bulk structural consequences of long-term (>2.5 years) deuterated water (D2O) exposure of intercalation materials with compositions Li x Ni 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) and Li x Ni 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) are studied by neutron powder diffraction (NPD). Detailed inspection of the NPD data reveals gradual formation of a secondary crystalline phase in all exposed samples, not previously reported for this system. This unknown phase forms faster in liquid- compared to vapor-exposed compounds. Structural modelling of the NPD data shows a stable level of Li/Ni anti-site defects and does not indicate any significant changes in lattice parameters or hydrogen-lithium (D + /Li + ) exchange in the structure. Consequently, the secondary phase formation must take place via transformation rather than modification of the parent material. X-ray photoelectron spectroscopy data indicate formation of LiHCO 3 /Li 2 CO 3 at the surface and a Li-deficient oxide in the sub-surface region of the pristine compounds, and the presence of adsorbed water and transition metal hydroxides at the exposed sample surfaces.

25 ENERGY STORAGE↗

NASA NTRS1977

Thermal interaction of the core and the mantle and long-term behavior of the geomagnetic field

The effects of temperature changes at the earth's core-mantle boundary on the velocity field of the core are analyzed. It is assumed that the geomagnetic field is maintained by thermal convection in the outer core. A model for the thermal interaction of the core and the mantle is presented which is consistent with current views on the presence of heat sources in the core and the properties of the lower mantle. Significant long-term variations in the frequency of geomagnetic reversals may be the result of fluctuating temperatures at the core-mantle boundary, caused by intermittent convection in the lower mantle. The thermal structure of the lower mantle region D double prime, extending from 2700 to 2900 km in depth, constitutes an important test of this hypothesis and offers a means of deciding whether the geomagnetic dynamo is thermally driven.

Jones, G. M.↗

DOE OSTI2022

Uranium sorption to organic matter and long-term accumulation in a pristine alpine wetland

Understanding the controls on uranium (U) mobility in the environment is key to improve the management of sites contaminated by U mining activities. Previous research has shown that natural or engineered wetlands are particularly able to scavenge high amounts of U(VI) and U(IV) under noncrystalline forms. However, questions remain on the respective roles of sorption and reduction processes in the removal of U from running waters in wetlands, as well as on the long-term stability of U storage. Here, we performed a series of geochemical, isotopic ($δ$ 238 U, ( 234 U/ 238 U)), microscopic (SEM-EDXS, EPMA) and spectroscopic (µ-XRF, µ-XAS, XANES and EXAFS at the U L 3 and M 4 -edges and Fe K-edge) investigations to determine the modes of U accumulation and assess U mobility in a natural exceptionally U-enriched (up to 5000 µg/g) wetland on the shore of Lake Nègre (Mediterranean Alps, France). Uranium (VI) was largely dominant in the two studied soil cores, except a few samples containing as much as ~50 % U(IV). At the particle scale, U is associated to a variety of organic constituents of the soil matrix with a homogenous oxidation state. Bulk EXAFS spectroscopy at the U L 3 -edge shows that U is mostly mononuclear, with dominant monodentate binding to organic moieties (C neighbors at ~3.45 Å). An additional minor fraction of U under polymeric forms is inferred from wavelet (CCWT) analysis of the EXAFS data. These observations are reinforced by 1 M bicarbonate extractions that result in the dissolution of 82–96 % of total U, including putative polymeric species. At the wetland scale, similar or slightly fractionated isotopic ratios ($δ$ 238 U) between the wetland-feeding creek waters and the wetland soils are observed, supporting the idea that U(VI) sorption on organic matter is the primary U scavenging mechanism. Furthermore, it indicates that partial U(VI) reduction to U(IV) occurs as a second step, after sorption. Analysis of U decay chain disequilibria in the cores as a function of depth suggests that U accumulation in this wetland has lasted for several thousand years. In conclusion, we propose that the wetland acts as an active reactor where U has been massively accumulating for ~14500 years, especially as U(VI) forms associated to organic matter and is further partly exported to the lake through soil erosion.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗

DOE OSTI2020

Long-Term Trends for Marine Sulfur Aerosol in the Alaskan Arctic and Relationships With Temperature

Marine aerosol plays a vital role in cloud-aerosol interactions during summer in the Arctic. The recent rise in temperature and decrease in sea ice extent have the potential to impact marine biogenic sources. Compounds like methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO 4 2- ), oxidation products of dimethyl sulfide (DMS) emitted by marine primary producers, are likely to increase in concentration. Long-term studies are vital to understand these changes in marine sulfur aerosol and potential interactions with Arctic climate. Samples were collected over three summers at two coastal sites on the North Slope of Alaska (Utqiagvik and Oliktok Point). MSA concentrations followed previously reported seasonal trends, with evidence of high marine primary productivity influencing both sites. When added to an additional data set collected at Utqiagvik, an increase in MSA concentration of + 2.5% per year and an increase in nss-SO 4 2- of + 2.1% per year are observed for the summer season over the 20-year record (1998–2017). This study identifies ambient air temperature as a strong factor for MSA, likely related to a combination of interrelated factors including warmer sea surface temperature, reduced sea ice, and temperature-dependent chemical reactions. Analysis of individual particles at Oliktok Point, within the North Slope of Alaska oil fields, showed evidence of condensation of MSA onto anthropogenic particles, highlighting the connection between marine and oil field emissions and secondary organic aerosol. Finally, this study shows the continued importance of understanding MSA in the Arctic while highlighting the need for further research into its seasonal relationship with organic carbon.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1978

Long-term studies with the Ariel-5 asm. 1: Her X-1, Vela X-1 and Cen X-3

Twelve hundred days of 3-6 keV X-ray data from Her X-1, Vela X-1 and Cen X-3 accumulated with the Ariel-5 all-sky monitor are interrogated. The binary periodicities of all three can be clearly observed, as can the approximately 35-d variation of Her X-1, for which we can refine the period to 34.875 plus or minus .030-d. No such longer-term periodicity less than 200-d is observed from Vela X-1. The 26.6-d low-state recurrence period for Cen X-3 previously suggested is not observed, but a 43.0-d candidate periodicity is found which may be consistent with the precession of an accretion disk in that system. The present results are illustrative of the long-term studies which can be performed on approximately 50 sources over a temporal base which will ultimately extend to at least 1800 days.

Holt, S. S.↗

NASA NTRS1973

Experimental program to determine long term characteristics of the MDE pressure transducers

The pressure cell sensors developed for the Pioneer 10/G meteoroid detection experiments (MDE) were investigated to enhance their application and their potential as a sensor in other MDE applications. Their Paschen characteristics were also investigated, and the effects of variations in geometry, Ni-63 platings (for initial ionizations) and sealing pressures were determined. The effects of extensive pre-flight testing and proton and heavy ion space radiation were investigated. Flight-quality pressure panels/cells were committed to long term testing to demonstrate their suitability for the Pioneer 10/G Missions.

Parker, C. D.↗

NASA NTRS2015

Long-Term Cryogenic Propellant Storage for the Titan Orbiter Polar Surveyor (TOPS) Mission

Cryogenic Propellant Storage↗

DOE OSTI2026

A comparison of long-term 37 Ar and 39 Ar transport and implications for 39 Ar as a persistent indicator of underground nuclear explosions

Measurements were first made in 2016 of legacy 39 Ar gas from the decades-old Barnwell underground nuclear explosion site within the Nevada National Security Site. This has raised the question of the ubiquity of the radionuclide 39 Ar following underground nuclear explosions in general locations. This article presents a high-level evaluation of the scientific case for using 39 Ar as a long-term indicator of underground nuclear explosions. Assessment is made based on a broad set of assumptions to reasonably estimate the persistence of 39 Ar in the subsurface environment following an explosion to establish potential detectability years to decades after the originating event.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

NASA NTRS1976

Long term performance of the advanced thermal control flight experiment

The Advanced Thermal Control Flight Experiment (ATFE) is providing the first zero-g flight data for the performance of a thermal diode heat pipe and an electrical Feedback Controlled Heat Pipe (FCHP). The temperature stability derived from the melting and freezing of octadecane is also being evaluated in this experiment. Flight data for the different operational modes are compared to ground test data, and the performance of the individual components is analyzed. Also, the ATFE's long term behavior from launch through September 30, 1975, is evaluated. The temperature control capability of a thermal diode, phase change material, and FCHP was demonstrated over more than 500 days of flight operation and each of these components should be considered in future applications. Both the diode and FCHP transport more than 20 W in the normal and passive modes during maximum conditions. Up to 30 W has been carried by the FCHP when the auxiliary heater is applied. The "OFF-conductance" of the diode has improved substantially in flight. A 1.4 W decrease in backflow has been realized by more complete blockage. The variable conductance behavior of the FCHP is essentially unchanged with time and relative to ground tests. Degradation of the radiator and reservoir surfaces have resulted in a partial loss of control by the FCHP during normal mode operation; however, manual control at an elevated set point has demonstrated the FCHP's ability to provide regulated temperature control to within + or - 2 C. The same pipe when operated as a passive VCHP controlled at 35 + or - 10 C with the same test conditions.

Brennan, P. J.↗

NASA NTRS2005

Development of Long-term Datasets from Satellite BUV Instruments: The "Soft" Calibration Approach

The first BUV instrument was launched in April 1970 on NASA's Nimbus4 satellite. More than a dozen instruments, broadly based on the same principle, but using very different technologies, have been launched in the last 35 years on NASA, NOAA, Japanese and European satellites. In this paper we describe the basic principles of the "soft" calibration approach that we have successfully applied to the data from many of these instruments to produce a consistent long-term record of total ozone, ozone profile and aerosols. This approach is based on using accurate radiative transfer models and assumed/known properties of the atmosphere in ultraviolet to derive calibration parameters. Although the accuracy of the results inevitably depends upon how well the assumed atmospheric properties are known, the technique has several built-in cross- checks that improve the robustness of the method. To develop further confidence in the data the soft calibration technique can be combined with data collected from few well- calibrated ground-based instruments. We will use examples from past and present BUV instruments to show how the method works.

Bhartia, Pawan K.↗

DOE OSTI2023

Long-term carbon intensity reduction potential of K-12 school buildings in the United States

School buildings have a great potential for carbon emission reduction since their annual emission is about 72 million metric tons. Currently, more than 30% of school buildings were built before 1960 and are underperforming. To effectively reduce carbon emissions via school building retrofits, it is critical for policymakers to understand the carbon intensity reduction potential of retrofitting school buildings in different regions. Hence, this study develops a method to comprehensively assess the long-term carbon intensity reduction potential of aggregated commercial buildings on a county-by-county basis in the continental U.S. We apply this method to the K-12 school buildings including primary and secondary school buildings. Here, this paper predicts the carbon intensity reduction potential of K-12 school buildings with eight building retrofit measures from 2022 to 2050 in the continental U.S. The results reveal several interesting findings: (1) In the approximately 3,000 counties of the U.S. from 2022 to 2050, the carbon intensity reduction potential of retrofitting K-12 school buildings in each county ranges from 0.41 kg/m 2 to 40.00 kg/m 2 . (2) Even in the same climate zone, the trends of carbon intensity reduction potential from 2022 to 2050 are different depending on their electricity sources. For example, in a hot and humid climate zone, the carbon intensity reduction potential in Florida will decrease from 2044 to 2048. However, in Mississippi, the carbon intensity reduction potential from 2044 to 2046 will increase due to the termination of the nuclear energy usage. (3) Generally, reducing lighting power density leads to more carbon intensity reduction in most states, but it might not be applicable for states with high clean energy penetration, such as Washington.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

NASA NTRS1986

A long-term study of SiO (v = 1, J = 2-1) maser emission from evolved stars and Orion A

General characteristics of eight late-type stars and Orion A in the SiO (v = 1, J = 2-1) maser line are reported based on observations made with the 20-m Onsala telescope between 1977 and 1984. Five stars show periodic maser flux variations that are well correlated with the infrared light curve, and the maximum SiO intensity and the dynamic range vary significantly between different periods and sources. Some long-term variations in the center velocity of the maser emission have been noted, with Omicron Cet possibly being a member of a binary system. Grand averages have been used to study the general velocity structure, and a global SiO (v = 1, J = 2-1) profile for Mira variables shows that the strongest emission is blueshifted with respect to the stellar velocity, while as a whole the emission is redshifted. The analysis places the SiO masers in a region between the pulsating stellar atmosphere and the expanding circumstellar envelope, where the velocity structure bears no relation to the expansion velocity of the shell.

Nyman, L.-A.↗

NASA NTRS1991

Discovery of a long-term periodic variation in LMC X-3

The highly variable X-ray luminosity of LMC X-3 is found to be strongly modulated with a period of about 198 (or possibly about 99) days. Observations from satellites show this periodic variation. For energies of less than 13 keV, the X-ray intensity and hardness are positively correlated; for higher energies, there appears to be no correlation. Available optical photometry indicates the mean V brightness also varies by more than 1 mag with this same long-term period. The regularity of this 'clock' in LMC X-3 suggests that it may be related to an accretion-disk precession, similar to that seen in LMC X-4, Her X-1, SS 433, or possibly periodic variations in the mass-transfer rate.

Cowley, A. P.↗