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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 1,783 records · Page 99
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Effect of microgravity and hypergravity on deposition of 0.5- to 3-micron-diameter aerosol in the human lung

We measured intrapulmonary deposition of 0. 5-, 1-, 2-, and 3-micron-diameter particles in four subjects on the ground (1 G) and during parabolic flights both in microgravity (microG) and at approximately 1.6 G. Subjects breathed aerosols at a constant flow rate (0.4 l/s) and tidal volume (0.75 liter). At 1 G and approximately 1.6 G, deposition increased with increasing particle size. In microG, differences in deposition as a function of particle size were almost abolished. Deposition was a nearly linear function of the G level for 2- and 3-micron-diameter particles, whereas for 0.5- and 1.0-micron-diameter particles, deposition increased less between microG and 1 G than between 1 G and approximately 1.6 G. Comparison with numerical predictions showed good agreement for 1-, 2-, and 3-micron-diameter particles at 1 and approximately 1.6 G, whereas the model consistently underestimated deposition in microG. The higher deposition observed in microG compared with model predictions might be explained by a larger deposition by diffusion because of a higher alveolar concentration of aerosol in microG and to the nonreversibility of the flow, causing additional mixing of the aerosols.

Flight Experiment↗
NASA NTRS1998

Multiple-breath washin of helium and sulfur hexafluoride in sustained microgravity

We performed multiple-breath washouts of N2 and simultaneous washins of He and SF6 with fixed tidal volume (approximately 1,250 ml) and preinspiratory lung volume (approximately the subject's functional residual capacity in the standing position) in four normal subjects (mean age 40 yr) standing and supine in normal gravity (1 G) and during exposure to sustained microgravity (microG). The primary objective was to examine the influence of diffusive processes on the residual, nongravitational ventilatory inhomogeneity in the lung in microG. We calculated several indexes of convective ventilatory inhomogeneity from each gas species. A normal degree of ventilatory inhomogeneity was seen in the standing position at 1 G that was largely unaltered in the supine position. When we compared the standing position in 1 G with microG, there were reductions in phase III slope in all gases, consistent with a reduction in convection-dependent inhomogeneity in the lung in microG, although considerable convective inhomogeneity persisted in microG. The reductions in the indexes of convection-dependent inhomogeneity were greater for He than for SF6, suggesting that the distances between remaining nonuniformly ventilated compartments in microG were short enough for diffusion of He to be an effective mechanism to reduce gas concentration differences between them.

NASA Discipline Cardiopulmonary↗
NASA NTRS1997

Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

In microgravity (microG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to microG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls (P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P < 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to microG.

Clinical Trial↗
NASA NTRS1996

Animal models and their importance to human physiological responses in microgravity

Two prominent theories to explain the physiological effects of microgravity relate to the cascade of changes associated with the cephalic shifts of fluids and the absence of tissue deformation forces. One-g experiments for humans used bed rest and the head-down tilt (HDT) method, while animal experiments have been conducted using the tail-suspended, head-down, and hindlimbs non-weightbearing model. Because of the success of the HDT approach with rats to simulate the gravitational effects on the musculoskeletal system exhibited by humans, the same model has been used to study the effects of gravity on the cardiopulmonary systems of humans and other vertebrates. Results to date indicate the model is effective in producing comparable changes associated with blood volume, erythropoiesis, cardiac mass, baroreceptor responsiveness, carbohydrate metabolism, post-flight VO2max, and post-flight cardiac output during exercise. Inherent with these results is the potential of the model to be useful in investigating responsible mechanisms. The suspension model has promise in understanding the capillary blood PO2 changes in space as well as the arterial PO2 changes in subjects participating in a HDT experiment. However, whether the model can provide insights on the up-or-down regulation of adrenoreceptors remains to be determined, and many investigators believe the HDT approach should not be followed to study gravitational influences on pulmonary function in either humans or animals. It was concluded that the tail-suspended animal model had sufficient merit to study in-flight and post-flight human physiological responses and mechanisms.

NASA Discipline Cardiopulmonary↗
NASA NTRS1996

Microgravity in the STS-29 space shuttle discovery affected the vestibular system of chick embryos

Out of 32 embryos flown (16 @ E2 + 16 @ E9) for 5 days, 16 survived. All sixteen E2 were dead at landing. Eight were opened and eight were incubated at 1.0G. Autopsy showed that 4 E2 survived over 24 hours in space. Eight E14 hatched without anatomical malformations, and 8 E14 were fixed. The height of the macular epithelia was 31 mu m (mean) in control and 26 mu m in flight chicks. The cross-sectional area of macular nuclei of control was 17 mu m(2) for hair cells and 14 mu m(2) in supporting cells. In flight, cross-sectional area was 17 mu m(2) in hair cells and 15 mu m(2) in supporting cells (n=250). The shape factor of cartilage cells (1.0 = perfect circle) between control (mean = 0.70) and flight (mean = 0.72), and the area of cartilaginous cells between controls (mean = 9 mu m(2)) and flight (mean = 9 mu m(2)) did not differ (n=300). The nuclei of support cells were closer to the basement membrane in flight than in control chicks. The immunoreactivity of otoconia with anti keratan, fibronectin or chrondroitin sulfate was not different between flight and control ears. There were more afferent fibers inside the macular epithelia of flight (p<0.05) than control. Three of 8 flight animals had elevated vestibular thresholds (VT), with normal mean response amplitudes and latencies. Modified afferent innervation patterns requiring weeks to compensate are sufficient to elevate VT, and should be investigated further. Other reversible (sublethal) microgravity effects on sensory epithelia (vacuoles, swelling, etc) require quantification.

Flight Experiment↗
NASA NTRS1993

Influence of simulated microgravity on the VO2 max of nontrained and trained rats

Head-down suspension (HDS) of rats has evolved as a useful model for the simulation of a microgravity environment. Previous HDS experiments with rats have shown an impaired capacity to perform aerobic exercise as demonstrated by reductions in maximum oxygen consumption (VO2 max), treadmill run time (RT), and mechanical efficiency (ME) of treadmill running at submaximal conditions. To determine whether endurance training (TR) before HDS would modify exercise performance, male Sprague-Dawley rats were assigned to nontrained (NT) or TR groups for 6 wk and exposed to HDS or cage control (CC) conditions for 29 days. The rats were tested for VO2 max, RT, and ME before treatment and on days 7, 14, 21, and 28. In addition, water and electrolyte excretion was measured on days 1 and 21 of the experimental period. Before HDS, the TR rats had significantly higher measures of VO2 max (15%) and RT (22%) than the NT rats. On day 28, HDS was associated with significant reductions in absolute VO2 max (ml/min) in TR (-30%) and NT (-14%) rats. Relative VO2 max (ml.min-1.kg-1) was significantly reduced in TR (-15%) but not NT rats. Similar reductions in RT occurred in TR (-37%) and NT (-35%) rats by day 28. ME was reduced 22% in both TR and NT rats after 28 days of suspension. HDS elicited diuresis, natriuresis, and kaliuresis in TR rats after 21 days but not after 24 h. In contrast, HDS-NT rats exhibited no diuretic, natriuretic, or kaliuretic responses.(ABSTRACT TRUNCATED AT 250 WORDS).

Non-NASA Center↗
NASA NTRS1993

Perceived self-orientation and self-motion in microgravity, after landing and during preflight adaptation training

The research described in this paper is intended to support development and evaluation of preflight adaptation training (PAT) apparatus and procedures. Successful training depends on appropriate manipulation of visual and inertial stimuli that control perception of self-motion and self-orientation. For one part of this process, astronauts are trained to report their self-motion and self-orientation experiences. Before their space mission, they are exposed to the altered sensory environments produced by the PAT trainers. During and after the mission, they report their motion and orientation experiences. Subsequently, they are again exposed to the PAT trainers and are asked to describe relationships between their experiences in microgravity and following entry and their experiences in the trainers.

Space Flight↗
NASA NTRS2004

Transitioning a Fundamental Research Program to Align with the NASA Exploration Initiative-Perspectives from Microgravity Combustion Science and Fluid Physics

A new Vision for Space Exploration was announced earlier this year by U.S. President George W. Bush. NASA has evaluated on-going programs for strategic alignment with this vision. The evaluation proceeded at a rapid pace and is resulting in changes to the scope and focus of experimental research that will be conducted in support of the new vision. The existing network of researchers in the physical sciences - a highly capable, independent, and loosely knitted community - typically have shared conclusions derived from their work within appropriate discipline-specific peer reviewed journals and publications. The initial result of introducing this Vision for Space Exploration has been to shift research focus from a broad coverage of numerous, widely varying topics into a research program focused on a nearly-singular set of supporting research objectives to enable advances in space exploration. Two of these traditional physical science research disciplines, Combustion Science and Fluid Physics, are implementing a course adjustment from a portfolio dominated by "Fundamental Science Research" to one focused nearly exclusively on supporting the Exploration Vision. Underlying scientific and engineering competencies and infrastructure of the Microgravity Combustion Science and Fluid Physics disciplines do provide essential research capabilities to support the contemporary thrusts of human life support, radiation countermeasures, human health, low gravity research for propulsion and materials and, ultimately, research conducted on the Moon and Mars. A perspective on how these two research disciplines responded to the course change will be presented. The relevance to the new NASA direction is provided, while demonstrating through two examples how the prior investment in fundamental research is being brought to bear on solving the issues confronting the successful implementation of the exploration goals.

Sutliff, Thomas J.↗
NASA NTRS2005

Morphological Evolution of Directional Solidification Interfaces in Microgravity: An Analysis of Model Experiments Performed on the International Space Station

A series of experiments performed using the Pore Formation and Mobility Investigation (PFMI) apparatus within the glovebox facility (GBX) on board the International Space Station (ISS) has provided video images of the morphological evolution of a three-dimensional interface in a diffusion controlled regime. The experimental samples were prepared on ground by filling glass tubes, 1 cm ID and approximately 30 cm in length, with "alloys" of succinonitrile (SCN) and water in an atmosphere of nitrogen at 450 millibar pressure. The compositions of the samples processed and analyzed are 0.25,0.5 and 1.0 wt% water. Experimental processing parameters of temperature gradient and translation speed, as well as camera settings, were remotely monitored and manipulated from the ground Telescience Center (TSC) at the Marshall !3pace Flight Center. During the experiments, the sample was first subjected to a unidirectional melt back, generally at 10 microns per second, with a constant temperature gradient ahead of the melting interface. Following the melt back, the interface was allowed to stabilize before translation is initiated. The temperatures in the sample were monitored by six in situ thermocouples and the position is monitored by an optical linear encoder. For the experiments performed and analyzed, the gradients ranged from 2.5 - 3.3 K/mm and the initial pulling velocities ranged from 0.7 micron per second to 1 micron per second with subsequent transition velocities of up to 100 microns per second. The data provided by the PFMI for analysis includes near-real-time (NRT) video captured on the ground during the experiment runs, ISS Video Tape Recorder (VTR) data dumped from the VTR at the end of the experiment run and recorded on the ground, telemetry data including temperature and position measurements, and limited flight HI-8 tapes in 2 camera views of experiment runs for which tapes have been returned to the investigators from ISS. Because of limited down mass from the ISS, the majority of the initial analysis has been performed using the NRT and VTR video data but will be supplemented with the HI-8 video as it becomes available. hardware and procedures required to prepare samples for correlation to flight samples is described. Using this ground-based system, a series of experiments have been performed for direct comparison with the flight data. The results of these comparisons as well as implications to future microgravity experiments are presented and discussed. A ground-based thin-sample directional solidification system as well as all associated

Strutzenberg, Louise L.↗
NASA NTRS2004

Ventless pressure control of two-phase propellant tanks in microgravity

This work studies pressurization and pressure control of a large liquid hydrogen storage tank. A finite element model is developed that couples a lumped thermodynamic formulation for the vapor region with a complete solution of the Navier-Stokes and energy equations for the flow and temperature fields in the liquid. Numerical results show that buoyancy effects are strong, even in microgravity, and can reposition a vapor bubble that is initially at the center of the tank to a region near the tank wall in a relatively short time. Long-term tank pressurization with the vapor bubble at the tank wall shows that after an initial transient lasting about a week, the final rate of pressure increase agrees with a purely thermodynamic analysis of the entire tank. However, the final pressure levels are quite different from thermodynamic predictions. Numerical results also show that there is significant thermal stratification in the liquid due to the effects of natural convection. A subcooled jet is used to provide simultaneous cooling and mixing in order to bring the tank pressure back down to its initial value. Three different jet speeds are examined. Although the lowest jet speed is ineffective at controlling the pressure because of insufficient penetration into the liquid region, the highest jet speed is shown to be quite effective at disrupting thermal stratification and reducing the tank pressure in reasonable time.

Weightlessness↗
NASA NTRS2004

Morphological changes in woody stem of Prunus jamasakura under simulated microgravity

When the four-week-old woody stem of Prunus jamasakura was grown under simulated microgravity condition on a three-dimensional clinostat, it bent at growth, and width of its secondary xylem decreased due to the reduction of fiber cell numbers and a smaller microfibril angle in the secondary cell wall, as reported in our previous paper. Gravity induces the development of the secondary xylem that supports the stem upward against the action of gravity. In this study, morphological changes of the tissues and cells were microscopically observed. Disorder was found in the concentric structure of tissues that organize the stem. The radial arrangement of the cells was also disturbed in the secondary xylem, and in the secondary phloem secondary cell walls of the bast fiber cells were undeveloped. These findings suggest that differentiation and development of the secondary xylem and the bast fiber cells are strongly controlled by terrestrial gravity. These tissue and cells functions to support the stem under the action of gravity. Furthermore, clinorotation induced disorder in the straight joint of vessel elements and the lattice-like structure of radial parenchyma cells, which is responsible for water transportation and storage, respectively. Gravity is an essential factor for keeping the division and differentiation normal in woody stem.

Prunus/cytology/physiology/ultrastructure↗
NASA NTRS1996

Radiative Ignition and the Transition to Flame Spread Investigated in the Japan Microgravity Center's 10-sec Drop Shaft

The Radiative Ignition and Transition to Spread Investigation (RITSI) is a shuttle middeck Glovebox combustion experiment developed by the NASA Lewis Research Center, the National Institute for Standards and Technology (NIST), and Aerospace Design and Fabrication (ADF). It is scheduled to fly on the third United States Microgravity Payload (USMP-3) mission in February 1996. The objective of RITSI is to experimentally study radiative ignition and the subsequent transition to flame spread in low gravity in the presence of very low speed air flows in two- and three-dimensional configurations. Toward this objective, a unique collaboration between NASA, NIST, and the University of Hokkaido was established to conduct 15 science and engineering tests in Japan's 10-sec drop shaft. For these tests, the RITSI engineering hardware was mounted in a sealed chamber with a variable oxygen atmosphere. Ashless filter paper was ignited during each drop by a tungsten-halogen heat lamp focused on a small spot in the center of the paper. The flame spread outward from that point. Data recorded included fan voltage (a measure of air flow), radiant heater voltage (a measure of radiative ignition energy), and surface temperatures (measured by up to three surface thermocouples) during ignition and flame spread.

Source record↗
NASA NTRS1997

Integrated Digital Video and Experimental Data Analysis for Microgravity Combustion Experiment

The purpose of the Diffusive and Radiative Transport in Fires (DARTFire) Project is to study various mechanisms of energy transport in the ignition and growth of flames in microgravity. This sounding rocket experiment incorporates two multispectral video cameras, two 8-mm video recorders, and several temperature and pressure probes that record information on two separate flames, burning under different oxygen concentrations and flow rates. Mirrors allow each camera to view side-by-side images of both flames.

Source record↗
NASA NTRS1997

Isothermal Dendritic Growth Experiment (IDGE) Is the First United States Microgravity Experiment Controlled From the Principal Investigator's University

The scientific objective of the Isothermal Dendritic Growth Experiment (IDGE) is to test fundamental assumptions about dendritic solidification of molten materials. IDGE is a microgravity materials science experiment using apparatus that was designed, built, tested, and operated by people from the NASA Lewis Research Center. The IDGE experiment was conceived by the principal investigator, Professor Martin E. Glicksman from Rensselaer Polytechnic Institute in Troy, New York. This experiment was a team effort of civil servants from the NASA Lewis Research Center, contractors from Aerospace Design & Fabrication, Inc. (ADF), and personnel at Rensselaer.

Malarik, Diane C.↗
NASA NTRS1998

NASA Lewis' Telescience Support Center Supports Orbiting Microgravity Experiments

The Telescience Support Center (TSC) at the NASA Lewis Research Center was developed to enable Lewis-based science teams and principal investigators to monitor and control experimental and operational payloads onboard the International Space Station. The TSC is a remote operations hub that can interface with other remote facilities, such as universities and industrial laboratories. As a pathfinder for International Space Station telescience operations, the TSC has incrementally developed an operational capability by supporting space shuttle missions. The TSC has evolved into an environment where experimenters and scientists can control and monitor the health and status of their experiments in near real time. Remote operations (or telescience) allow local scientists and their experiment teams to minimize their travel and maintain a local complement of expertise for hardware and software troubleshooting and data analysis. The TSC was designed, developed, and is operated by Lewis' Engineering and Technical Services Directorate and its support contractors, Analex Corporation and White's Information System, Inc. It is managed by Lewis' Microgravity Science Division. The TSC provides operational support in conjunction with the NASA Marshall Space Flight Center and NASA Johnson Space Center. It enables its customers to command, receive, and view telemetry; monitor the science video from their on-orbit experiments; and communicate over mission-support voice loops. Data can be received and routed to experimenter-supplied ground support equipment and/or to the TSC data system for display. Video teleconferencing capability and other video sources, such as NASA TV, are also available. The TSC has a full complement of standard services to aid experimenters in telemetry operations.

Hawersaat, Bob W.↗
NASA NTRS1997

Colloidal Disorder-Order Transition Experiment Probes Particle Interactions in Microgravity

Everything in the universe is made up of the same basic building blocks - atoms. All physical properties of matter such as weight, hardness, and color are determined by the kind of atoms present and the way they interact with each other. The Colloidal Disorder-Order Transition (CDOT) shuttle flight experiment tested fundamental theories that model atomic interactions. The experiment was part of the Second United States Microgravity Laboratory (USML-2) aboard the Space Shuttle Columbia, which flew from October 20 to November 5, 1995.

Source record↗
NASA NTRS2003

The Low Temperature Microgravity Physics Facility: Progress and Status

The Jet Propulsion Laboratory (JPL) is developing the Low Temperature Microgravity Physics Facility (LTMPF). The LTMPF is a multiple user and multiple flight facility that will provide a long duration low temperature environment for performing state of the art experiments at the International Space Station (ISS). During each mission, two distinct primary experiments will be accommodated. Secondary experiments utilizing the hardware built for the primary experiments will also be accommodated during each mission. Over the past year, much progress has occurred on the LTMPF as the flight hardware has started to be built. Also, many changes have occurred. Last summer, the initial flight of the LTMPF was delayed until early 2008 by a 2-year slip in the delivery of the Japanese Experiment Module (KIBO) Exposed Facility of the ISS, where the LTMPF will be attached when it flies. Finally, the experiments that will fly as part of the first mission have been changed so that one Gravitational and Relativistic experiment and one Low Temperature Condensed Matter experiment will fly on each flight of the LTMPF. Therefore, the experiments that will fly on the initial mission of the LTMPF will be DYNAMX and the Superconducting Microwave Oscillator Experiment (SUMO).

Larson, Melora↗