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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 253 records · Page 14

All sources NASA NTRS DOE OSTI

NASA NTRS1986

Imagery with a Si:Bi 16 x 16 array

A description of the design and performance of an imaging spectrometer intended for operation in the 7 to 14 micron wavelength range is presented. It is based upon a 16 by 16 element Si:Bi hybrid array, a circular variable filter wheel, and a microcomputer data acquisition system. The spatial-spectral photometric performances were evaluated in the laboratory as well as field tested at astronomical observatories. The performance characteristics of the system are presented as well as laboratory and astronomical images.

Goebel, J. H.↗

NASA NTRS1987

Pre- and posttreatment techniques for spacecraft water recovery

The objective was to develop techniques for satisfactory pretreatment of waste water (urine and wash water) prior to recovery by distillation and satisfactory post-treatment of the recovered water and humidity condensate for purification to the high quality necessary for reuse. The effort included literature and laboratory investigations, feasibility evaluations of candidate approaches, and development of conceptual designs for a waste water pretreatment system and a recovered water post-treatment system.

Putnam, David F.↗

NASA NTRS1985

Photometric imaging near infrared spectrometer

A description of the design and performance of an imaging spectrometer intended for operation in the seven to fourteen micrometer wavelength range is presented. It is based upon a sixteen by sixteen element Si:Bi hybrid array, a circular variable filter wheel, and a microcomputer data acquisition system. The spatial-spectral photometric performances have been evaluated in the laboratory as well as field tested at astronomical observatories. The performance characteristics of the system are presented as well as laboratory and astronomical images.

Goebel, J. H.↗

NASA NTRS1987

Selected materials issues associated with Space Station

Compatibility of Space Station hardware with the space environment is one of the major materials development issues. The projected long life of the Space Station elements (about 30 years for structural components and 20 years for power systems), the large number of day/night thermal cycles that have to be withstood during the life of the Station, and the effects of atomic oxygen and UV irradiation on exposed surfaces demand new considerations in selection of materials. Reaction efficiencies of materials for Space Station applications derived from LEO experiments are presented together with surface recession predictions for various Space Station components. Developments in the areas of protective coatings and of laboratory facilities for evaluating the effects of atomic oxygen are discussed.

Leger, L.↗

NASA NTRS1987

Microgravity research applications of interferometry to heat and mass transfer

Major space flight experiments which have used interferometric measurement as a major support system are described together with similar ground-based research. Space experiments include those flown on Spacelab 3 ad on the D-1 mission. Included in the ground-based experiments are aircraft studies, Spacelab 3 data reduction and evaluation, and supportive laboratory hardware development. It is shown that optical measurement techniques are crucial to microgravity research.

Owen, Robert B.↗

NASA NTRS1989

Digital 8-DPSK Modem For Trellis-Coded Communication

Digital real-time modem processes octuple differential-phase-shift-keyed trellis-coded modulation. Intended for use in communicating data at rate up to 4.8 kb/s in land-mobile satellite channel (Rician fading) of 5-kHz bandwidth at carrier frequency of 1 to 2 GHz. Modulator and demodulator contain digital signal processors performing modem functions. Design flexible in that functions altered via software. Modem successfully tested and evaluated in both laboratory and field experiments, including recent full-scale satellite experiment. In all cases, modem performed within 1 dB of theory. Other communication systems benefitting from this type of modem include land mobile (without satellites), paging, digitized voice, and frequency-modulation subcarrier data broadcasting.

Jedrey, T. C.↗

NASA NTRS1988

A fine resolution multifrequency polarimetric FM radar

A fine resolution polarimetric FM SAR was developed for optimization of polarimetric SARs and interpretation of SAR data via controlled experiments with surface-base sensors. The system is designed for collecting polarimetric data at 5.3 and 10 GHz over incidence angles from 0 to 60 deg. Features of the system include broad bandwidth to obtain fine range resolution, phase stabilization and linearization loop circuitry, and digital signal processing capability. The system is used in a research program to collect polarimetric backscatter data from artificial sea ice research and design trade-offs, laboratory and field evaluation, as well as results from experiments on artificial sea ice are presented.

Bredow, J.↗

NASA NTRS1988

Short-crack growth behaviour in an aluminum alloy: An AGARD cooperative test program

An AGARD Cooperative Test Program on the growth of short fatigue cracks was conducted to define the significance of the short-crack effect, to compare test results from various laboratories, and to evaluate an existing analytical crack-growth prediction model. The initiation and growth of short fatigue cracks (5 micrometer to 2 mm) from the surface of a semi-circular notch in 2024-T3 aluminum alloy sheet material were monitored under various load histories. The cracks initiated from inclusion particle clusters or voids on the notch surface and generally grew as surface cracks. Tests were conducted under several constant-amplitude (stress ratios of -2, -1, 0, and 0.5) and spectrum (FALSTAFF and Gaussian) loading conditions at 3 stress levels each. Short crack growth was recorded using a plastic-replica technique. Over 250 edge-notched specimens were fatigue tested and nearly 950 cracks monitored by 12 participants from 9 countries. Long crack-growth rate data for cracks greater than 2 mm in length were obtained over a wide range in rates (10 to the -8 to 10 to the -1 mm/cycle) for all constant-amplitude loading conditions. Long crack-growth rate data for the FALSTAFF and Gaussian load sequences were also obtained.

Newman, J. C., Jr.↗

NASA NTRS1989

A prototype gas exchange monitor for exercise stress testing aboard NASA Space Station

This paper describes an easy-to-use monitor developed to track the weightlessness deconditioning aboard the NASA Space Station, together with the results of testing of a prototype instrument. The monitor measures the O2 uptake and CO2 production, and calculates the maximum O2 uptake and anaerobic threshold during an exercise stress test. The system uses two flowmeters in series to achieve a completely automatic calibration, and uses breath-by-breath compensation for sample line-transport delay. The monitor was evaluated using two laboratory methods and was shown to be accurate. The system's block diagram and the bench test setup diagram are included.

Orr, Joseph A.↗

NASA NTRS1989

A vapor generator for transonic flow visualization

A vapor generator was developed for use in the NASA Langley Transonic Dynamics Tunnel (TDT). Propylene glycol was used as the vapor material. The vapor generator system was evaluated in a laboratory setting and then used in the TDT as part of a laser light sheet flow visualization system. The vapor generator provided satisfactory seeding of the air flow with visible condensate particles, smoke, for tests ranging from low subsonic through transonic speeds for tunnel total pressures from atmospheric pressure down to less than 0.1 atmospheric pressure.

Bruce, Robert A.↗

NASA NTRS1989

Microbial identification system for Space Station Freedom

The Environmental Health System (EHS) and Health Maintenance Facility (HMF) on Space Station Freedom will require a comprehensive microbiology capability. This requirement entails the development of an automated system to perform microbial identifications on isolates from a variety of environmental and clinical sources and, when required, to perform antimicrobial sensitivity testing. The unit currently undergoing development and testing is the Automated Microbiology System II (AMS II) built by Vitek Systems, Inc. The AMS II has successfully completed 12 months of laboratory testing and evaluation for compatibility with microgravity operation. The AMS II is a promising technology for use on Space Station Freedom.

Brown, Harlan D.↗

NASA NTRS1992

Development of a truss joint for robotic assembly of space structures

This report presents the results of a detailed study of mechanical fasteners which were designed to facilitate robotic assembly of structures. Design requirements for robotic structural assembly were developed, taking into account structural properties and overall system design, and four candidate fasteners were designed to meet them. These fasteners were built and evaluated in the laboratory, and the Hammer-Head joint was chosen as superior overall. It had a high reliability of fastening under misalignments of 2.54 mm (0.1 in) and 3 deg, the highest end fixity (2.18), the simplest end effector, an integral capture guide, good visual verification, and the lightest weight (782 g, 1.72 lb). The study found that a good design should incorporate chamfers sliding on chamfers, cylinders sliding on chamfers, and hard surface finishes on sliding surfaces. The study also comments on robot flexibility, sag, hysteresis, thermal expansion, and friction which were observed during the testing.

Parma, George F.↗

NASA NTRS1992

Issues/considerations and performance prediction of LEO protective coatings

Organic materials can be used in low earth orbit for long periods only if they are made to be durable to atomic oxygen in addition to the threats of ultraviolet radiation, micrometeoroid and debris impact, thermal cycling, and charged particle radiation. In many materials applications, it is more cost-effective to utilize atomic oxygen protective coatings over materials which are vulnerable to attack by atomic oxygen rather than developing alternative materials which are inherently durable. Many metal and metal oxide coatings have been shown to be potentially suitable for long term protection of organic polymers in low earth orbit. The protection afforded by thin film coatings on polymeric substrates is highly dependent on the completeness of coverage of the coating. Thus, the prime indicator of durability is the size and abundance of pin windows and scratches in the protective coating. Such defects depend on the deposition technique, smoothness of the surface to be protected, and presence of particulate contaminants. Issues and considerations relevant to substrate preparation, deposition of protective coatings, ground laboratory simulation and evaluation of threats in low earth orbit to protective materials, results of in-space tests, and the use of Monte Carlo modeling techniques to predict in-space durability are presented in graphic form.

Banks, Bruce A.↗

NASA NTRS1991

Observations and analysis of oil spills using polarized imagery

On Saturday, July 28, 1990, a train of barges collided with the Greek tanker Shinoussa in Galveston Bay off Red Fish Island near Texas City, Texas. The first barge sank and the second began to leak while the third barge in the chain and the Shinoussa both escaped without damage. The NASA Flight Science Support Office sponsored a graduate student from SUNY - College of Environmental Science and Forestry and a student from Texas, to survey the damage. The purpose of these surveys was to correlate aircraft base data with orbital data obtained during the Space Shuttle Polarization Experiment and existing laboratory data to evaluate the potential for an application such as oil spill monitoring and mapping. NASA has no charter with the local response agencies to support oil spill monitoring and cleanup.

Israel, S. A.↗

NASA NTRS1992

Structural materials from lunar simulants through thermal liquefaction

Thermal liquefaction that allows development of intermediate ceramic composites from a lunar simulant with various admixtures is used to develop structural materials for construction on the moon. Bending and compressive properties of resulting composites are obtained from laboratory tests and evaluated with respect to the use of three different types and fibers.

Desai, Chandra S.↗

NASA NTRS1995

Improved, Easier-To-Use Tunneling Infrared Sensors

Designs of electron-tunneling infrared sensors and micromachining processes used to fabricate them modified to increase sensitivity and to simplify operation, adjustment, and associated circuitry. Corrugations, pinholes, and standard packaging incorporated into design. Deflection voltages reduced, and thermal drifts eliminated. Performances exceed those of other commercially available, uncooled infrared sensors. Operation of sensors simplified to such extent, now feasible to ship them to nonexpert users for routine testing and evaluation in their laboratories.

Muller, Richard E.↗

NASA NTRS1994

Spectral control of an alexandrite laser for an airborne water-vapor differential absorption lidar system

A narrow-linewidth pulsed alexandrite laser has been greatly modified for improved spectral stability in an aircraft environment, and its operation has been evaluated in the laboratory for making water-vapor differential absorption lidar measurements. An alignment technique is described to achieve the optimum free spectral range ratio for the two etalons inserted in the alexandrite laser cavity, and the sensitivity of this ratio is analyzed. This technique drastically decreases the occurrence of mode hopping, which is commonly observed in a tunable, two-intracavity-etalon laser system. High spectral purity (greater than 99.85%) at 730 nm is demonstrated by the use of a water-vapor absorption line as a notch filter. The effective cross sections of 760-nm oxygen and 730-nm water-vapor absorption lines are measured at different pressures by using this laser, which has a finite linewidth of 0.02 cm(exp -1) (FWHM). It is found that for water-vapor absorption linewidths greater than 0.04 cm(exp -1) (HWHM), or for altitudes below 10 km, the laser line can be considered monochromatic because the measured effective absorption cross section is within 1% of the calculated monochromatic cross section. An analysis of the environmental sensitivity of the two intracavity etalons is presented, and a closed-loop computer control for active stabilization of the two intracavity etalons in the alexandrite laser is described. Using a water-vapor absorption line as a wavelength reference, we measure a long-term frequency drift (approximately 1.5 h) of less than 0.7 pm in the laboratory.

Ponsardin, Patrick↗

NASA NTRS1996

Mechanics of Granular Materials (MGM)

The constitutive behavior of uncemented granular materials such as strength, stiffness, and localization of deformations are to a large extend derived from interparticle friction transmitted between solid particles and particle groups. Interparticle forces are highly dependent on gravitational body forces. At very low effective confining pressures, the true nature of the Mohr envelope, which defines the Mohr-Coulomb failure criterion for soils, as well as the relative contribution of each of non-frictional components to soil's shear strength cannot be evaluated in terrestrial laboratories. Because of the impossibility of eliminating gravitational body forces on earth, the weight of soil grains develops interparticle compressive stresses which mask true soil constitutive behavior even in the smallest samples of models. Therefore the microgravity environment induced by near-earth orbits of spacecraft provides unique experimental opportunities for testing theories related to the mechanical behavior of terrestrial granular materials. Such materials may include cohesionless soils, industrial powders, crushed coal, etc. This paper will describe the microgravity experiment, 'Mechanics of Granular Materials (MGM)', scheduled to be flown on Space Shuttle-MIR missions. The paper will describe the experiment's hardware, instrumentation, specimen preparation procedures, testing procedures in flight, as well as a brief summary of the post-mission analysis. It is expected that the experimental results will significantly improve the understanding of the behavior of granular materials under very low effective stress levels.

Alshibli, Khalid A.↗