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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Fabrication and Thermo-Optical Properties of the MLS Composite Primary Reflector

The Microwave Limb Sounder (MLS) is a limb-sounding radiometer sensing emissions in the millimeter and sub-millimeter range. MLS will contribute to an understanding of atmospheric chemistry by assessing stratospheric and tropospheric ozone depletion, climate forcings and volcanic effects. The heart of the antenna is the primary reflector, constructed from graphite/cyanate composites in a facesheet/core construction. The reflector has an aperture of one square meter, a mass of 8.7 kilos and final figure accuracy of 4.37 microns rms. The surface is also modified to ensure RF reflectivity, prevent solar concentration and provide thermal balance to the spacecraft The surface is prepared by precision beadblasting, then coated with vapor deposited aluminum (VDA) and finally a layer of silicon suboxide (SiO(x)) to control the infrared emissivity. The resulting surface has a solar absorptance of 0.43 and an absorptance/emittance ratio of 1.3. BRDF analysis shows that 93% of the incident thermal energy is reflected outside a 10 degree angle of cone. For its mass and aperture, we believe this reflector to have the highest figure accuracy yet achieved in a composite antenna construction.

Willis, Paul B.↗
NASA NTRS2000

Knowledge Preservation Techniques That Can Facilitate Intergroup Communications

We have developed tools, social methods and software, for (1) acquiring technical knowledge from engineers and scientists, (2) preserving that knowledge, (3) making the totality of our stored knowledge rapidly searchable. Our motivation has been, mainly, to preserve rare knowledge of senior engineers who are near retirement. Historical value of such knowledge, and also of our tools, has been pointed out to us by historians. We now propose the application these tools to enhancing communication among groups that are working jointly on a project. Of most value will be projects having groups among whom communication is rare and incomplete. We propose that discussions among members of a group be recorded in audio and that both the actual audio and transcriptions of that audio, and optional other pieces be combined into electronic, webpage-like "books". These books can then be searched rapidly by interested people in other groups. At points of particular interest, a searcher can zoom in on the text and even on the original recordings to pick up nuances (e.g. to distinguish a utterance said in seriousness from one in sarcasm). In this matter, not only can potentially valuable technical details be preserved for the future, but communication be enhanced during the life of a joint undertaking.

Moreman, Douglas↗
NASA NTRS2003

Space, Atmospheric, and Terrestrial Radiation Environments

The progress on developing models of the radiation environment since the 1960s is reviewed with emphasis on models that can be applied to predicting the performance of microelectronics used in spacecraft and instruments. Space, atmospheric, and ground environments are included. It is shown that models must be adapted continually to account for increased understanding of the dynamics of the radiation environment and the changes in microelectronics technology. The IEEE Nuclear and Space Radiation Effects Conference is a vital forum to report model progress to the radiation effects research community.

Barth, Janet L.↗
NASA NTRS2003

Chandra Detection of a Pulsar Wind Nebula Associated With Supernova Remnant 3C 396

We present a 100 ks observation of the Galactic supernova remnant 3C396 (G39.2-0.3) with the Chandra X-Ray Observatory that we compare to a 20cm map of the remnant from the Very Large Array. In the Chandra images, a nonthermal nebula containing an embedded pointlike source is apparent near the center of the remnant which we interpret as a synchrotron pulsar wind nebula surrounding a yet undetected pulsar. From the 2-10 keV spectrum for the nebula (N(sub H) = 5.3 plus or minus 0.9 x 10(exp 22) per square centimeter, GAMMA =1.5 plus or minus 0.3) we derive an unabsorbed x-ray flux of S(sub z)=1.62 x 10(exp -12) erg per square centimeter per second, and from this we estimate the spin-down power of the neutron star to be E(sup dot) = 7.2 x 10(exp 36) ergs per second. The central nebula is morphologically complex, showing bent, extended structure. The radio and X-ray shells of the remnant correlate poorly on large scales, particularly on the eastern half of the remnant, which appears very faint in X-ray images. At both radio and X-ray wavelengths the western half of the remnant is substantially brighter than the east.

Olbert, C. M.↗
NASA NTRS1999

A Deployable Primary Mirror for Space Telescopes

NASA Langley Research Center, Composite Optics, Inc., and Nyma/ADF have developed jointly a deployable primary mirror for space telescopes that combines over five years of research on deployment of optical-precision structures and over ten years of development of fabrication techniques for optical-precision composite mirror panels and structures. The deployable mirror is directly applicable to a broad class of non-imaging "lidar" (light direction a nd ranging) telescopes whose figure-error requirements are in the range of one to ten microns RMS. Furthermore, the mirror design can be readily modified to accommodate imaging-quality reflector panels and active panel-alignment control mechanisms for application to imaging telescopes. The present paper: 1) describes the deployable mirror concept; 2) explains the status of the mirror development; and 3) provides some technical specifications for a 2.55- m-diameter, proof-of-concept mirror. Keywords: precision deployment, hinge joint, latch joint, deployable structures, fabrication, space telescopes, optical instruments, microdynamics.

Lake, Mark S.↗
NASA NTRS2004

Expanding Remote Science Operations Capabilities Onboard the International Space Station

EXPRESS Racks have been supporting payload science operations onboard the International Space Station (ISS) since April of 2001. EXPRESS is an acronym that stands for "EXpedite the PRocessing of Experiments to Space Station." This name reflects NASA's focus to simplify the process of manifesting experiments and maximizing scientific research capabilities by providing a robust, remotely operated payload support platform. The EXPRESS Rack System was developed by NASA's Marshall Space Flight Center (MSFC) and built by The Boeing Company in Huntsville, Alabama. Eight EXPRESS racks were built and five are currently onboard the ISS supporting science operations. The design and development of the EXPRESS Rack System is a long story that has been documented in previous publications. This paper briefly describes the facilities used to develop and verify flight software, test operational capabilities. It then traces the advancements made in the operational capabilities of the EXPRESS Racks from the time they were launched on STS-100 through the present. The paper concludes with a description of potential enhancements that will make the EXPRESS racks one of the most advanced and capable remote science platforms ever developed.

Cruzen, Craig A.↗
NASA NTRS2002

X-ray synchronization emitting Fe-rich ejecta in SNR RCW 86

Supernova remnants may exhibit both thermal and nonthermal X-ray emission. In a previous study with ASCA data, we found that the middle-aged supernova remnant RCW 86 showed evidence for both processes, and predicted that observations with much higher spatial resolution would distinguish harder X-rays, which we proposed were primarily synchrotron emission, from softer, thermal X-rays. Here we describe Chandra observations which amply confirm our predictions.

ISM individual (RCW86) supernova remnants↗
NASA NTRS2006

The Making of a Self-Neglect Severity Scale

Research in elder self-neglect has lagged behind that of other forms of mistreatment, despite the fact that self-neglect is the most common allegation reported to Adult Protective Service agencies throughout the US. The lack of a gold-standard to measure self-neglect has hampered efforts to study this phenomenon. Researchers designed the Self-neglect Severity Scale (SSS) based on interviews with Adult Protective Service workers and a national expert panel. The SSS is based on observation and interview and is administered in the home to include an environmental assessment. It was piloted, extensively field tested and then revised. The CREST SSS was developed using survey data and consultation with experts in the field. This instrument utilizes observer ratings, interview responses, and assesses subjects physical and environmental domains. It also assesses functional status as it relates to health and safety issues. After field and pilot testing the SSS was finalized and is currently undergoing reliability and validity testing. The CREST SSS was developed as a state scale to provide a common language for describing cases of self-neglect. It is the first self-neglect severity scale available to researchers. If found to be both reliable and valid it can be used in future intervention studies.

Smith, Scott M.↗
NASA NTRS2006

Identification of Technologies for Provision of Future Aeronautical Communications

This report describes the process, findings, and recommendations of the second of three phases of the Future Communications Study (FCS) technology investigation conducted by NASA Glenn Research Center and ITT Advanced Engineering & Sciences Division for the Federal Aviation Administration (FAA). The FCS is a collaborative research effort between the FAA and Eurocontrol to address frequency congestion and spectrum depletion for safety critical airground communications. The goal of the technology investigation is to identify technologies that can support the longterm aeronautical mobile communication operating concept. A derived set of evaluation criteria traceable to the operating concept document is presented. An adaptation of the analytical hierarchy process is described and recommended for selecting candidates for detailed evaluation. Evaluations of a subset of technologies brought forward from the prescreening process are provided. Five of those are identified as candidates with the highest potential for continental airspace solutions in L-band (P-34, W-CDMA, LDL, B-VHF, and E-TDMA). Additional technologies are identified as best performers in the unique environments of remote/oceanic airspace in the satellite bands (Inmarsat SBB and a custom satellite solution) and the airport flight domain in C-band (802.16e). Details of the evaluation criteria, channel models, and the technology evaluations are provided in appendixes.

Gilbert, Tricia↗
NASA NTRS2007

Continuously Regenerable Freeze-Out CO2 Control Technology

Carbon dioxide (CO2) removal technology development for portable life support systems (PLSS) has traditionally concentrated in the areas of solid and liquid chemical sorbents and semi-permeable membranes. Most of these systems are too heavy in gravity environments, require prohibitive amounts of consumables for operation on long term planetary missions, or are inoperable on the surface of Mars due to the presence of a CO2 atmosphere. This paper describes the effort performed to mature an innovative CO2 removal technology that meets NASA s planetary mission needs while adhering to the important guiding principles of simplicity, reliability, and operability. A breadboard cryogenic carbon dioxide scrubber (Cryo Scrubber) for a closed loop cryogenic PLSS was developed, designed, and tested, and a conceptual design suitable for a PLSS was developed based on the results of the breadboard testing. The Cryo Scrubber freezes CO2 and other trace contaminants out of expired vent loop gas using cooling available from a liquid oxygen (LOX) based PLSS. The device is continuously regenerable, with solid CO2 being removed from the cold freeze-out surfaces, sublimated, and vented overboard. Duration is limited only by the supply of LOX stored in the PLSS. Simplicity, reliability, and operability are universally important criteria for critical hardware on long duration Lunar or Mars missions. The Cryo Scrubber has no moving parts, requires no additional consumables, and uses no electrical power, contributing to its simplicity and reliability. It is easy to use; no operator action is required to prepare, use, or shut down the Cryo Scrubber, and it does not require charging or regeneration. The versatility of the concept allows for operation on earth, the moon, and Mars, and in microgravity.

Fricker, John↗
NASA NTRS2000

Composite isogrid structures for parabolic surfaces

The invention relates to high stiffness parabolic structures utilizing integral reinforced grids. The parabolic structures implement the use of isogrid structures which incorporate unique and efficient orthotropic patterns for efficient stiffness and structural stability.

Silverman, Edward M.↗
NASA NTRS2006

Fat-Soluble Vitamin Status in Self-Neglecting Elderly

Elder self-neglect is a form of elder mistreatment. The systematic characterization of self-neglecting individuals is the goal of the CREST project. Reported here is the evaluation of fat-soluble vitamin status. Self-neglect (SN) subjects were recruited and consented following referral from Adult Protective Services. Control (CN) subjects were matched for age, gender, race, and socioeconomic status, as possible. We report here on 47 SN subjects (age 77 plus or minus 7, mean plus or minus SD; body weight 76 kg plus or minus 26) and 40 CN subjects (77 y plus or minus 7, 79 kg plus or minus 20). Blood samples were analyzed for indices of fat-soluble vitamin status. Plasma retinol (p less than 0.01) was lower in SN subjects. Plasma tocopherol tended (p less than 0.06) to be lower in SN subjects, while gamma-tocopherol was unchanged. SN subjects tended to have lower serum 25-OH vitamin D (p less than 0.11), and to be vitamin D deficient (26% below 23 mmol/L). Hypercalcemia occurred more often in SN subjects (23% had values above 2.56 mmol/L), as did elevated parathyroid hormone concentrations (p less than 0.05). These data demonstrate that many nutrients are affected in the self-neglecting elderly, and that long-term deficits are evident by the nature of changes in fat soluble vitamins.

Kala, G.↗
NASA NTRS2006

Nutritional Status in Self-Neglecting Elderly

Elder self-neglect is the most common, and most compelling form of elder mistreatment. Individuals who cannot provide the basic needs for themselves may develop social, functional, and physical deficits. The CREST project has the goal of systematically characterizing these individuals, and the objective of the study reported here is to characterize aspects of their nutritional status. Self-neglect (SN) subjects referred from Adult Protective Services were recruited and consented. Control (CN) subjects were matched for age, gender, race, and socio-economic status when possible. Reported here are data on 47 SN subjects (age 77 +/- 7, mean +/- SD; body weight 76 kg +/- 26) and 40 CN subjects (77 +/- 7, 79 kg +/- 20). Blood samples were analyzed for indices of nutritional status. SN subjects had higher serum concentrations of homocysteine (p < 0.01) and methylmalonic acid (p < 0.05). Red blood cell folate levels were lower (p < 0.01) in the SN subjects and serum folate levels tended (p < 0.07) to be lower, also. C-reactive protein concentrations were higher than 10 mg/dL in 36% of SN subjects and 18% of CN subjects. Total cholesterol and triglyceride concentrations were similar in the two groups. These data demonstrate that the self-neglecting elderly population is at risk with respect to several markers of nutritional status.

Oliver, S. Mathews↗
NASA NTRS2009

Homocysteine and Cognitive Performance in Elders with Self-Neglect

Elevated plasma homocysteine has been associated with altered cognitive performance in older adults. Elders referred to Adult Protective Services (APS) for self-neglect have been reported to have elevated plasma homocysteine levels and to suffer from cognitive impairment. This study assesses the association, if any, between plasma homocysteine and cognitive performance among elders with self-neglect. Methods: Sixty-five community-living adults, 65 years of age and older, reported to Adult Protective Services for self-neglect and 55 matched controls (matched for age, ethnicity, gender and socio-economic status) consented and participated in this study. The research team conducted in-home comprehensive geriatric assessments which included the mini-mental state exam (MMSE), the 15-item geriatric depression scale (GDS), the Wolf-Klein Clock Drawing Tests (CDT) and a comprehensive nutritional biochemistry panel, which included plasma homocysteine. Student s t tests and Pearson correlations were conducted to assess for bivariate associations. Results: Elders with self-neglect had significantly higher plasma homocysteine levels (M=12.68umol/L, sd=4.4) compared to the controls (M=10.40umol/L, sd=3.61;t=3.21, df=127, p=.002). There were no statistically significant associations between cognitive performance and plasma homocysteine in the self-neglect group, however there was a significant correlation between plasma homocysteine and the CDT among the controls (r=-.296, p=.022). Conclusion: Mean plasma homocysteine levels were significantly higher in elders with self-neglect, however, they do not appear to be related to cognitive performance, indicating that cognitive impairment in elder self-neglect involve mechanisms other than hyperhomocysteinemia. These findings warrant further investigation

Burnett, J.↗
NASA NTRS2009

Parathyroid Hormone Levels and Cognition

Hyperparathyroidism is a well-recognized cause of impaired cognition due to hypercalcemia. However, recent studies have suggested that perhaps parathyroid hormone itself plays a role in cognition, especially executive dysfunction. The purpose of this study was to explore the relationship of parathyroid hormone levels in a study cohort of elders with impaied cognition. Methods: Sixty community-living adults, 65 years of age and older, reported to Adult Protective Services for self-neglect and 55 controls matched (on age, ethnicity, gender and socio-economic status) consented and participated in this study. The research team conducted in-home comprehensive geriatric assessments which included the Mini-mental state exam (MMSE), the 15-item geriatric depression scale (GDS) , the Wolf-Klein clock test and a comprehensive nutritional panel, which included parathyroid hormone and ionized calcium. Students t tests and linear regression analyses were performed to assess for bivariate associations. Results: Self-neglecters (M = 73.73, sd=48.4) had significantly higher PTH levels compared to controls (M =47.59, sd=28.7; t=3.59, df=98.94, p<.01). There was no significant group difference in ionized calcium levels. Overall, PTH was correlated with the MMSE (r=-.323, p=.001). Individual regression analyses revealed a statistically significant correlation between PTH and MMSE in the self-neglect group (r=-.298, p=.024) and this remained significant after controlling for ionized calcium levels in the regression. No significant associations were revealed in the control group or among any of the other cognitive measures. Conclusion: Parathyroid hormone may be associated with cognitive performance.

Burnett, J.↗