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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

A new method for monitoring long term calibration of the SBUV and TOMS instruments

A new method has been developed to monitor the long-term calibration of the Solar Backscatter Ultraviolet (SBUV) and Total Ozone Mapping Spectrometer (TOMS) instruments. It is based on the fact that the radiance in one channel can be expressed as a linear sum of the radiances in neighboring channels. Using simulated radiances for the SBUV and TOMS instruments, various scenarios of changes in instrument calibration are investigated. Results from sample processing of SBUV data are also presented.

Ahmad, Z.↗
NASA NTRS1991

Long-term anabolic effects of prostaglandin-E2 on tibial diaphyseal bone in male rats

The effects of long-term prostaglandin E2 (PGE2) on tibial diaphyseal bone were studied in 7-month-old male Sprague-Dawley rats given daily subcutaneous injections of 0, 1, 3 and 6 mg PGE2/kg/day for 60, 120 and 180 days. The tibial shaft was measured by single photon absorptiometry and dynamic histomorphometric analyses were performed on double-fluorescent labeled undecalcified tibial diaphyseal bone samples. Exogenous PGE2 administration produced the following transient changes in a dose-response manner between zero and 60 days: (1) increased bone width and mineral density; (2) increased total tissue and total bone areas; (3) decreased marrow area; (4) increased periosteal and corticoendosteal lamellar bone formation; (5) activated corticoendosteal lamellar and woven trabecular bone formation; and (6) activated intracortical bone remodeling. A new steady-state of increased tibial diaphyseal bone mass and elevated bone activities were observed from day 60 onward. The elevated bone mass level attained after 60 days of PGE2 treatment was maintained at 120 and 180 days. These observations indicate that the powerful anabolic effects of PGE2 will increase both periosteal and corticoendosteal bone mass and sustain the transient increase in bone mass with continuous daily administration of PGE2.

Jee, Webster S. S.↗
NASA NTRS2023

Paint and Oil Locker, SWMU 067 Southern Treatment Area Air Sparge System Construction Completion and Performance Monitoring and Paint and Oil Locker, Northern Area (SWMU 067) and Supply Warehouse #3, SWMU 088 Long-Term Monitoring Report Kennedy Space Center, Florida

This Air Sparge (AS) System Construction Completion, Performance Monitoring, and Long-Term Monitoring (LTM) Report presents activities conducted at the Paint and Oil Locker (POL) (Solid Waste Management Unit [SWMU] 067) and Supply Warehouse #3 (SW3) (SWMU 088) sites located at the Kennedy Space Center (KSC), Florida. Activities include implementation and Year 1 (Quarters [Q] 1 through 4) and Q5 operation, maintenance, and monitoring (OM&M) activities and performance monitoring results for the AS Interim Measure (IM) in the POL Southern Treatment Area, LTM results for the POL Northern Area and SW3, and supplemental direct push technology (DPT) sampling at both sites to support the LTM and performance monitoring programs. The timeframe for activities included in this report extends from August 2019 to August 2022. The scope for these sites currently includes two main components, which are documented within this report: (1) LTM at SW3 and POL Northern Area where an AS system began operation at these sites in May 2009 and June 2013, respectively, and subsequently turned off for both sites in March 2018 (during the previous reporting period); and (2) Active AS operations and performance monitoring in the POL Southern Treatment Area where an AS system was installed and began operation in 2021. The AS IM in the POL Southern Treatment Area was implemented between 2019 and 2021 to treat a chlorinated solvent groundwater plume that resulted from historic operations supporting the National Aeronautics and Space Administration’s (NASA) Space Program. The objective of the AS IM is to remediate groundwater within the treatment zone to support transition to monitored natural attenuation (MNA). The overall Corrective Action objective is to reduce concentrations of trichloroethene (TCE), cis-1,2-dichloroethene (cDCE), trans-1,2- dichloroethene (tDCE), and vinyl chloride (VC) present in groundwater to levels below their respective State of Florida Groundwater Cleanup Target Levels (GCTLs). The AS IM was installed in the POL Southern Treatment Area to target the high concentration plume (HCP), which includes a source zone (SZ) area where TCE was found to exceed 11,000 micrograms per liter (µg/L), and extend to a depth of 30 feet below land surface (bls).

TCE↗
NASA NTRS2019

Shortsighted Evolution Constrains the Efficacy of Long-Term Bet Hedging

To survive unpredictable environmental change, many organisms adopt bet-hedging strategies that are initially costly but provide a long-term fitness benefit. The temporal extent of these deferred fitness benefits determines whether bet-hedging organisms can survive long enough to realize them. In this article, we examine a model of microbial bet hedging in which there are two paths to extinction: unpredictable environmental change and demographic stochasticity. In temporally correlated environments, these drivers of extinction select for different switching strategies. Rapid phenotype switching ensures survival in the face of unpredictable environmental change, while slower-switching organisms become extinct. However, when both switching strategies are present in the same population, then demographic stochasticity—enforced by a limited population size—leads to extinction of the faster-switching organism. As a result, we find a novel form of evolutionary suicide whereby selection in a fluctuating environment can favor bet-hedging strategies that ultimately increase the risk of extinction. Population structures with multiple subpopulations and dispersal can reduce the risk of extinction from unpredictable environmental change and shift the balance so as to facilitate the evolution of slower-switching organisms.

Bet hedging↗
NASA NTRS1975

Main principles used for building up a data bank for the long-term storage and retrieval of scientific space data

Methodological, technical, and practical organizational problems are considered of constructing a long term data bank. Data processing flowcharts are presented which are based on an analysis of the tasks which the data bank must fulfill, an estimate of the existing and predicted data flows in the processing center, and the selection of the data storage media and the forms in which the data are presented. Questions related to the use of standard and special hardware and software in the data bank are discussed. Reasons are presented for the adopted structure of the document-fact type information retrieval system which permits the mechanization and automation of various stages in the retrieval and selection of the data.

Zlotin, G. N.↗
NASA NTRS1986

Long-term amplitude and phase stability of the 400-kW 2.115-GHz transmitter

Results of recent measurements of the long-term phase, amplitude and group delay stability of the 400-kW S-band (2.115-GHz) transmitter are reported. Various control parameters which are responsible for many of the observed instabilities are identified. Further tests to identify the parameters responsible for the remaining instabilities are suggested.

Hoppe, D. J.↗
NASA NTRS1990

Ground-based laser DIAL system for long-term measurements of stratospheric ozone

A ground-based differential absorption lidar system has been implemented to make long-term, precise measurements of stratospheric ozone concentration profiles from about 20 to 50 km altitude. This lidar is located at an elevation of 2300 m in the San Gabriel Mountains, Southern California, and has been in operation since January 1988. A high power (100-W) excimer laser system and a 90-cm diam telescope are used to achieve the desired performance levels. This paper describes the implementation of the system and its operation including the procedures for data analysis. Examples of ozone profiles measured, and intercomparisons with measurements made by other instruments, are presented which show that the lidar, in its present configuration, is capable of producing high quality ozone measurements from 20 km up to at least 45 km.

Mcdermid, Stuart I.↗
NASA NTRS1992

Long-term effects of microgravity and possible countermeasures

The measures that can be taken to counteract the effect of long-term exposures to microgravity are discussed. It is noted that, although it was shown that specially designed exercise programs can counteract the effect of exposures of up to one year in space, is it questionable whether U.S. astronauts could or should have to maintain such regimes for extremely prolonged missions. The methods considered by NASA Life Sciences Division are to provide an artificial gravity environment by the generation of centrifugal forces by means of either the continuous rotation of the whole spacecraft or using a short-arm centrifuge on board a zero-g spacecraft. Results obtained in studies of these two methods are discussed, and the centrifuge research facility that is presently being developed by NASA is described.

Wolfe, James W.↗
NASA NTRS2002

Long-Term Properties of Accretion Discs in X-ray Binaries: The Variable Third Period in SMC X-1 - 1

Long term X-ray monitoring data from the RXTE All Sky Monitor (ASM) reveal that the third (superorbital) period in SMC X-1 is not constant but varies between 40-60 days. A dynamic power spectrum analysis indicates that the third period has been present continuously throughout the five years of ASM observations. This period changed smoothly from 60 days to 45 days and then returned to its former value, on a timescale of approximately 1600 days. During the nearly 4 years of overlap between the CGRO & RXTE missions, the simultaneous BATSE hard X-ray data confirm this variation in SMC X-1. Sources of systematic error and possible artefacts are investigated and found to be incapable of reproducing the results reported here. Our disco cry of such an instability in the superorbital period of SMC X-1 is interpreted in the context of recent theoretical studies of warped, precessing accretion discs. We find that the behaviour of SMC X-1 is consistent with a radiation - driven warping model.

Charles, P. A.↗
NASA NTRS2010

Decline in Aerobic Fitness After Long-Term Stays on the International Space Station

U.S. and non-Russian International Partner astronauts who participate in long-term International Space Station (ISS) expeditions perform submaximal cycle exercise tests before, during, and after space flight. The heart rate (HR) and oxygen uptake (VO2) responses to exercise are used to estimate peak VO2 (EVO2pk). Purpose: To determine if the following factors are associated with the preflight-to-post flight change in EVO2pk: gender, age, body weight (BW), number of aerobic exercise sessions/wk- during flight, length of flight, EVO2pk measured before and late during the flight, ISS Expedition number and time between landing and the first post flight test. Methods: Records of 37 ISS astronauts (30 male, BW=81.6 plus or minus 8.6 kg; 7 female BW=66.1 plus or minus 4.9 kg [mean plus or minus SD]), age 46 plus or minus 4 years, were retrospectively examined. Peak HR and VO2 were measured approximately 9 months before flight to establish the test protocol. The submaximal cycle test consisted of three 5-minute stages designed to elicit 25, 50, and 75% of VO2pk. EVO2pk was calculated using linear least-squares extrapolation of average HR and VO2 during the last minute of each stage to predict VO2 at maximal HR. VO2 was not measured during flight and was assumed to not be different from preflight. Testing was performed 45 days before launch, late during flight, and during the week after landing. A random-intercept multivariate model was used to determine which characteristics significantly contributed to post flight EVO2pk. Results: In-flight aerobic exercise averaged 5.4 plus or minus 1.2 sessions/wk. ISS flight duration averaged 163 plus or minus 39 d. Mean EVO2pk values were 3.41 plus or minus 0.64 L (raised dot) per minute before flight, 3.09 plus or minus 0.57 L (raised dot) per minute late in flight, and 3.02 plus or minus 0.65 L (raised dot) per minute after flight. Late- and after-flight values were lower (p less than 0.05) than preflight values and did not differ from each other. Time between landing and post flight testing was 4.5 plus or minus 1.6 days. The only factor significantly associated with the post flight EVO2pk value was the late-flight EVO2pk score. Conclusion: Testing performed late during a mission provides a prediction of EVO2pk after landing. This approach may be implemented during longer missions.

Lynn, Peggy A.↗
NASA NTRSDate not supplied

Long-Term Corrosivity at NASA Kennedy Space Center as a Function of Distance and Time from the Atlantic Ocean

Long-term data to record both seasonal and notional bounding values for corrosivity at multiple sites at NASA Kennedy Space Center was needed to make better materials choices for NASA-based ground and spaceflight programs. The data was valuable for two key reasons, 1) to measure corrosion rate and chloride concentration as a function of time and distance from the Atlantic Ocean, and 2) compare the corrosivity at launchpad and site-specific areas to the more accelerated conditions at the KSC Beachside Atmospheric Corrosion Test Site for coating and materials performance prediction. Sites were chosen from 45 meter (150 feet) to 8 kilometers (5 miles) from the Atlantic Ocean and corrosion variables at each site were measured throughout each year from June 2017 to April 2023, except the Beachside site, which includes data from November 2010. The summary includes corrosivity data and coating performance comparisons at select sites, which will be used as the updated NASA corrosivity standard for corrosion control requirements.

NASA↗
NASA NTRS1974

Observations on saccules of rats exposed to long-term hypergravity

The saccules of 15 centrifuged rats and 15 control rats were examined for morphological alterations resulting from long-term exposure to hypergravity. Minimal changes were found confined to the otolithic membrane. They were a slight decrease in the overall volume of otolithic membrane, a redistribution of otoconia in the direction of the gravitational force, and a more pronounced 'accessory' membrane. These changes were interpreted as purely mechanical effects of hypergravity, causing accelerated displacement of otoconia and subsequent entrapment of some of them on inferior portions of the primary otolithic membrane and 'accessory' membrane.

Lim, D. J.↗
NASA NTRS1979

Long-term risk analysis associated with nuclear waste disposal in space

An assessment and verification of previous analytic results on the long term risk of earth reentry for hazardous payloads is presented. The two areas were studied: (1) stability of nominal, near-circular storage orbits in the regions between Venus and earth and between earth and Mars, and (2) probability of earth reentry for off-nominal planet-crossing orbits resulting from deployment system failures. In the first area, numerical integrations of the equations of motion are compared with stability predications based on secular perturbation theory. The agreement is good in terms of the heliocentric distances covered and the general behavior of the orbital history, although certain near-resonance situations can lead to difficulty. In the second area, a Monte Carlo simulation of orbital evolution is used and the results compared with Opik's analytic theory of planetary encounters and collision statistics, with data verified to within a close order-of-magnitude.

Friedlander, A. L.↗