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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 109 records · Page 6

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NASA NTRS1991

Metabolism and biochemistry in hypogravity

The headward shift of body fluid and increase in stress-related hormones that occur in hypogravity bring about a number of changes in metabolism and biochemistry of the human body. Such alterations may have important effects on health during flight and during a recovery period after return to earth. Body fluid and electrolytes are lost, and blood levels of several hormones that control metabolism are altered during space flight. Increased serum calcium may lead to an increased risk of renal stone formation during flight, and altered drug metabolism could influence the efficacy of therapeutic agents. Orthostatic intolerance and an increased risk of fracturing weakened bones are concerns at landing. It is important to understand biochemistry and metabolism in hypogravity so that clinically important developments can be anticipated and prevented or ameliorated.

Leach, Carolyn S.↗

NASA NTRS1991

Effects of gravity on the circadian period in rats

The effect of increased gravity force on the circadian period of body temperature and activity of rats was investigated using rats implanted with a small radio telemetry device and, after a 2-week recovery and a 3-week control period at 1G, rotated at for 4 weeks at a constant 2G field in a 18-ft-diam centrifuge. Measurements of the mean freerunning period of the temperature and activity rhythms after 10 days showed that the exposure to 2G led to a functional separation of the pacemakers that regulate the activity and the temperature in the animals. Each pacemaker reacted differently: the activity period increased and the temperature period decreased. By the third or the fourth week, the activity and the temperature periods have returned to 1G control levels.

Murakami, Dean M.↗

NASA NTRS1992

Effects of isolation on interferon production and hematological and immunological parameters

A 27-year-old woman was maintained in an isolated state for 131 days in Carlsbad Caverns, New Mexico. Her diet was vitamin D-depleted. Determinations on the effects of such isolation on levels and activities of peripheral blood cells that are important for hematological homeostasis and immunological function were carried out. Throughout the duration of the study, the percentage of lymphoid cells that expressed CD3, CD4, CD8, CD19, Leu 8, and other markers remained relatively constant although the absolute numbers of these cells varied. Although the percentage of natural killer (NK) cells did not vary, the activity of these cells did change. NK cell activity became elevated as the isolation study progressed. Production of interferon-gamma (IFN-gamma) in response to mitogen stimulation was higher than expected throughout the isolation periods, but returned to the normal range after termination of the isolation. Red and white cell counts dropped significantly upon entering isolation, but soon returned to normal.

NASA Discipline Cell Biology↗

NASA NTRS1999

The Genesis Trajectory and Heteroclinic Cycles

The Genesis Mission will be NASA's first robotic sample return mission. The purpose of this mission is to collect solar wind samples for two years in L1 halo orbit and return it to the Utah Test and Training Range (UTTR) for mid-air retrieval by helicopters.

Genesis Halo Orbit Sample Return periodic orbits a↗

NASA NTRS2006

The Novel Nonlinear Adaptive Doppler Shift Estimation Technique and the Coherent Doppler Lidar System Validation Lidar

The signal processing aspect of a 2-m wavelength coherent Doppler lidar system under development at NASA Langley Research Center in Virginia is investigated in this paper. The lidar system is named VALIDAR (validation lidar) and its signal processing program estimates and displays various wind parameters in real-time as data acquisition occurs. The goal is to improve the quality of the current estimates such as power, Doppler shift, wind speed, and wind direction, especially in low signal-to-noise-ratio (SNR) regime. A novel Nonlinear Adaptive Doppler Shift Estimation Technique (NADSET) is developed on such behalf and its performance is analyzed using the wind data acquired over a long period of time by VALIDAR. The quality of Doppler shift and power estimations by conventional Fourier-transform-based spectrum estimation methods deteriorates rapidly as SNR decreases. NADSET compensates such deterioration in the quality of wind parameter estimates by adaptively utilizing the statistics of Doppler shift estimate in a strong SNR range and identifying sporadic range bins where good Doppler shift estimates are found. The authenticity of NADSET is established by comparing the trend of wind parameters with and without NADSET applied to the long-period lidar return data.

Beyon, Jeffrey Y.↗

DOE OSTI2018

Estimation of emigration, return migration, and transit migration between all pairs of countries

We propose a method for estimating migration flows between all pairs of countries that allows for decomposition of migration into emigration, return, and transit components. Current state-of-the-art estimates of bilateral migration flows rely on the assumption that the number of global migrants is as small as possible. We relax this assumption, producing complete estimates of all between-country migration flows with genuine estimates of total global migration. We find that the total number of individuals migrating internationally has oscillated between 1.13 and 1.29% of the global population per 5-year period since 1990. Return migration and transit migration are big parts of total migration; roughly one of four migration events is a return to an individual’s country of birth. In the most recent time period, we estimate particularly large return migration flows from the United States to Central and South America and from the Persian Gulf to south Asia.

Science & Technology - Other Topics↗

NASA NTRS2016

An Efficient Approach for Mars Sample Return Using Emerging Commercial Capabilities

Mars Sample Return is the highest priority science mission for the next decade as recommended by the 2011 Decadal Survey of Planetary Science. This article presents the results of a feasibility study for a Mars Sample Return mission that efficiently uses emerging commercial capabilities expected to be available in the near future. The motivation of our study was the recognition that emerging commercial capabilities might be used to perform Mars Sample Return with an Earth-direct architecture, and that this may offer a desirable simpler and lower cost approach. The objective of the study was to determine whether these capabilities can be used to optimize the number of mission systems and launches required to return the samples, with the goal of achieving the desired simplicity. All of the major element required for the Mars Sample Return mission are described. Mission system elements were analyzed with either direct techniques or by using parametric mass estimating relationships. The analysis shows the feasibility of a complete and closed Mars Sample Return mission design based on the following scenario: A SpaceX Falcon Heavy launch vehicle places a modified version of a SpaceX Dragon capsule, referred to as "Red Dragon", onto a Trans Mars Injection trajectory. The capsule carries all the hardware needed to return to Earth Orbit samples collected by a prior mission, such as the planned NASA Mars 2020 sample collection rover. The payload includes a fully fueled Mars Ascent Vehicle; a fueled Earth Return Vehicle, support equipment, and a mechanism to transfer samples from the sample cache system onboard the rover to the Earth Return Vehicle. The Red Dragon descends to land on the surface of Mars using Supersonic Retropropulsion. After collected samples are transferred to the Earth Return Vehicle, the single-stage Mars Ascent Vehicle launches the Earth Return Vehicle from the surface of Mars to a Mars phasing orbit. After a brief phasing period, the Earth Return Vehicle performs a Trans Earth Injection burn. Once near Earth, the Earth Return Vehicle performs Earth and lunar swing-bys and is placed into a Lunar Trailing Orbit - an Earth orbit, at lunar distance. A retrieval mission then performs a rendezvous with the Earth Return Vehicle, retrieves the sample container, and breaks the chain of contact with Mars by transferring the sample into a sterile and secure container. With the sample contained, the retrieving spacecraft makes a controlled Earth re-entry preventing any unintended release of Martian materials into the Earth's biosphere. The mission can start in any one of three Earth to Mars launch opportunities, beginning in 2022.

Commercial↗

DOE OSTI2019

Siberian Miscanthus sacchariflorus accessions surpass the exceptional chilling tolerance of the most widely cultivated clone of Miscanthus x giganteus

Abstract Chilling temperatures (0–15°C) inhibit photosynthesis in most C 4 grasses, yet photosynthesis is chilling tolerant in the ‘Illinois’ clone of the C 4 grass Miscanthus x giganteus , a candidate cellulosic bioenergy crop. M. x giganteus is a hybrid between Miscanthus sacchariflorus and Miscanthus sinensis ; therefore chilling‐tolerant parent lines might produce hybrids superior to the current clone. Recently a collection of M. sacchariflorus from Siberia, the apparent low temperature limit of natural distribution , became available, which may be a source for chilling tolerance. The collection was screened for chilling tolerance of photosynthesis by measuring dark‐adapted maximum quantum yield of PSII photochemistry ( F v /F m ) on plants in the field in cool weather. Superior accessions were selected for further phenotyping: plants were grown at 25°C, transferred to 10°C (chilling) for 15 days, and returned to 25°C for 7 days (recovery). Two experiments assessed: (a) light‐saturated net photosynthetic rate ( A sat ) and operating quantum yield of PSII photochemistry (Φ PSII ), (b) response of net leaf CO 2 uptake ( A ) to intercellular [CO 2 ] ( c i ). Three accessions showed superior chilling tolerance: RU2012‐069 and RU2012‐114 achieved A sat up to double that of M. x giganteus prior to and during chilling, due to increased c i ‐ saturated photosynthesis ( V max ). RU2012‐069 and RU2012‐114 also maintained greater levels of Φ PSII during chilling, indicating reduced photodamage. Additionally, accession RU2012‐112 maintained a stable A sat throughout the 15‐day chilling period, while A sat continuously declined in other accessions; this suggests RU2012‐112 could outperform others in lengthy chilling periods. Plants were returned to 25°C after the chilling period; M. x giganteus showed the weakest recovery after 1 day, but a strong recovery after 1 week. This study has therefore identified important genetic resources for the synthesis of improved lines of M. x giganteus , which could facilitate the displacement of fossil fuels by cellulosic bioenergy.

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS2011

Possible Increase in Nitric Oxide Production by Lightning Discharges Due to Catalytic Effects of Ice Particles

We address the question of whether ice crystals with habits typically encountered by lightning discharges may serve as catalysts for the production of NOx by lightning. If so, and if the effect is sufficiently large, it would need to be taken into account in estimates of global NOx production by lightning. In this study, we make a series of plausible assumptions about the temperatures and concentrations of reactant species in the environment of discharges and we postulate a mechanism by which ice crystals could adsorb nitrogen atoms. We then compare production rates between uncatalyzed and catalyzed reactions at 2000 K, 3000 K, and 4000 K, temperatures observed in lightning channels during the cool-down period after a return stroke. Catalyzed NO production rates are greater at 2000 K, whereas uncatalyzed production occurs most rapidly at 4000 K. The channel temperature stays around 2000 K for a longer period of time than at 4000 K. The longer residence time at 2000 K is sufficient to allow fresh reactants to participate in the mix in. Therefore, our results suggest that nearly three times as much NO per flash is produced by ice-catalyzed reactions as compared with uncatalyzed reactions.

Peterson, Harold↗

NASA NTRS1986

Improved solution of the lidar equation utilizing particle counter measurements

The extraction of particle backscattering from incoherent lidar measurements poses some problems. In the case of measurements of the stratospheric aerosol layer the solution of the lidar equation is based on two assumptions which are necessary to normalize the measured signal and to correct it with the two-way transmission of the laser pulse. Normalization and transmission are tackled by adding the information contained in aerosol particle counter measurements of the University of Wyoming to the ruby lidar measurements at Garmisch-Partenkirchen. Calculated backscattering from height levels above 25 km for the El Chichon period will be compared with lidar measurements and necessary corrections. The calculated backscatter-to-extinction ratios are compared to those, which were derived from a comparison of published extinction values to measured lidar backscattering at Garmisch. These ratios were used to calculate the Garmisch lidar returns. For the period 4 to 12 months after the El Chichon eruption a backscater-to-extinction ratio of 0.026 1/sr was applied with smaller values before and after that time.

Jaeger, H.↗

NASA NTRS2011

Effects of Bed Rest on Conduction Velocity of the Triceps Surae Stretch Reflex and Postural Control

Despite rigorous exercise and nutritional management during space missions, astronauts returning from microgravity exhibit neuromuscular deficits and a significant loss in muscle mass in the postural muscles of the lower leg. Similar changes in the postural muscles occur in subjects participating in long-duration bed rest studies. These adaptive muscle changes manifest as a reduction in reflex conduction velocity during head-down bed rest. Because the stretch reflex encompasses both the peripheral (muscle spindle and nerve axon) and central (spinal synapse) components involved in adaptation to calf muscle unloading, it may be used to provide feedback on the general condition of neuromuscular function, and might be used to evaluate the effectiveness of countermeasures aimed at preserving muscle mass and function during periods of unloading. Stretch reflexes were measured on 18 control subjects who spent 60 to 90 days in continuous 6 deg head-down bed rest. Using a motorized system capable of rotating the foot around the ankle joint (dorsiflexion) through an angle of 10 degrees at a peak velocity of about 250 deg/sec, a stretch reflex was recorded from the subject's left triceps surae muscle group. Using surface electromyography, about 300 reflex responses were obtained and ensemble-averaged on 3 separate days before bed rest, 3 to 4 times in bed, and 3 times after bed rest. The averaged responses for each test day were examined for reflex latency and conduction velocity (CV) across gender. Computerized posturography was also conducted on these same subjects before and after bed rest as part of the standard measures. Peak-to-peak sway was measured during Sensory Organization Tests (SOTs) to evaluate changes in the ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Although no gender differences were found, a significant increase in reflex latency and a significant decrease in CV were observed during the bed rest period, with a return to baseline 3 to 5 days after bed rest, depending on the duration of bed rest. In addition, a relationship between CV and loss of muscle strength in the lower leg was observed post bed rest for most subjects. Immediately post-bed rest, most subjects showed decreased performance on SOTs, with the greater decrements on sway-referenced support and head movement conditions. Post-bed rest decrements were less than typically observed following spaceflight. Decrements in postural control and the stretch reflex can be primarily attributed to the unloading mechanisms this ground-based analog provides. The stretch reflex is a concise test measurement that can be obtained during the head-down phase of bed rest, as it does not interfere with the bed rest paradigm. This makes it an ideal tool that can detect, early on, whether a countermeasure is successful in preserving muscle function.

Reschke, M. F.↗

NASA NTRS2006

Assessment of Postflight Locomotor Performance Utilizing a Test of Functional Mobility: Strategic and Adaptive Responses

Space flight induces adaptive modification in sensorimotor function, allowing crewmembers to operate in the unique microgravity environment. This adaptive state, however, is inappropriate for a terrestrial environment. During a re-adaptation period upon their return to Earth, crewmembers experience alterations in sensorimotor function, causing various disturbances in perception, spatial orientation, posture, gait, and eye-head coordination. Following long duration space flight, sensorimotor dysfunction would prevent or extend the time required to make an emergency egress from the vehicle; compromising crew safety and mission objectives. We are investigating two types of motor learning that may interact with each other and influence a crewmember's ability to re-adapt to Earth's gravity environment. In strategic learning, crewmembers make rapid modifications in their motor control strategy emphasizing error reduction. This type of learning may be critical during the first minutes and hours after landing. In adaptive learning, long-term plastic transformations occur, involving morphological changes and synaptic modification. In recent literature these two behavioral components have been associated with separate brain structures that control the execution of motor strategies: the strategic component was linked to the posterior parietal cortex and the adaptive component was linked to the cerebellum (Pisella, et al. 2004). The goal of this paper was to demonstrate the relative contributions of the strategic and adaptive components to the re-adaptation process in locomotor control after long duration space flight missions on the International Space Station (ISS). The Functional Mobility Test (FMT) was developed to assess crewmember s ability to ambulate postflight from an operational and functional perspective. Sixteen crewmembers were tested preflight (3 sessions) and postflight (days 1, 2, 4, 7, 25) following a long duration space flight (approx 6 months) on the ISS. We have further analyzed the FMT data to characterize strategic and adaptive components during the postflight readaptation period. Crewmembers walked at a preferred pace through an obstacle course set up on a base of 10 cm thick medium density foam (Sunmate Foam, Dynamic Systems, Inc., Leicester, NC). The 6.0m X 4.0m course consisted of several pylons made of foam; a Styrofoam barrier 46.0cm high that crewmembers stepped over; and a portal constructed of two Styrofoam blocks, each 31cm high, with a horizontal bar covered by foam and suspended from the ceiling which was adjusted to the height of the crewmember s shoulder. The portal required crewmembers to bend at the waist and step over a barrier simultaneously. All obstacles were lightweight, soft and easily knocked over. Crewmembers were instructed to walk through the course as quickly and as safely as possible without touching any of the objects on the course. This task was performed three times in the clockwise direction and three times in the counterclockwise direction that was randomly chosen. The dependent measures for each trial were: time to complete the course (seconds) and the number of obstacles touched or knocked down. For each crewmember, the time to complete each FMT trial from postflight days 1, 2, 4, 7 and 25 were further analyzed. A single logarithmic curve using a least squares calculation was fit through these data to produce a single comprehensive curve (macro). This macro curve composed of data spanning 25 days, illustrates the re-adaptive learning function over the longer time scale term. Additionally, logarithmic curves were fit to the 6 data trials within each individual post flight test day to produce 5 separate daily curves. These micro curves, produced from data obtained over the course of minutes, illustrates the strategic learning function exhibited over a relative shorter time scale. The macro curve for all subjects exhibited adaptive motor learning patterns over the 25 day period. Howev, 9/16 crewmembers exhibited significant strategic motor learning patterns in their micro curves, as defined by m > 1 in the equation of the line y=m*LN(x) +b. These data indicate that postflight recovery in locomotor function involves both strategic and adaptive mechanisms. Future countermeasures will be designed to enhance both recovery processes.

Warren, L. E.↗

DOE OSTI2026

Towaoc Housing Solar Initiative

The Towaoc Housing Solar initiative was implemented to install net-metered solar generation systems on twenty-three Tribal buildings in Towoac, CO on the Ute Mountain Ute Reservation. The project was funded 80% by Department of Energy and 20% by the Ute Mountain Ute Tribe. The project and grant are authorized by Ute Mountain Ute Tribal Council Resolution 2020-116. The systems were designed to cumulatively generate 160 direct current (DC) kilowatts on average, translating to 222,585 kilowatt hours per year. The average cost for the generation was calculated at $\$$3.34/watt with a return on investment period anticipated at 22 years for a simple payback of all costs, 11 years for the Tribe’s investment at 50% cost-share. The systems should last for 30 years. The primary goals of the project for the Tribe were identified as the reduction of electricity costs for the twenty three Tribal buildings of the Housing Authority (comprising 22 rental homes and a small apartment building with 11 units) and the reduction of carbon pollution through the transition of energy sources used in the buildings.

14 SOLAR ENERGY↗

NASA NTRS1975

On the periodic coordination of linear stochastic systems

The decentralized stochastic control of a linear dynamic system consisting of several subsystems is considered. A two-level approach is used by the introduction of a coordinator who collects measurements from the local controllers periodically and in return transmits coordinating parameters. Two types of coordination are considered: open-loop feedback and closed loop. The resulting control laws are found to be intuitively attractive.

Chong, C.-Y.↗

NASA NTRS1988

Astrometric observations of comets and asteroids and subsequent orbital investigations

The 155-cm reflector was used for observations of comets and minor planets on 28 nights during April-October. Twenty-two of the observations refer to comets, 62 to numbered minor planets (numbered, that is, by the end of the semester: only nine of them refer to minor planets already numbered at the time of the last report), and the remainer to unnumbered minor planets. Observations were made of four new comets discovered during the semester and a fifth discovered in January. Observations of Wilson (19861), P/Tempel 2 and two other returning short-period comets are also continuing. Among the odd numbered minor planets observed were the earth-approaching objects (1685) Toro and (1980) Tezcatlipoca. The Earth approacher 1980 PA was numbered (3908).

Mccroskey, Richard E.↗

NASA NTRS1993

Further probing of the X-ray source in NGC 4151 - New constraints on the nuclear geometry

We report on the results of new Ginga observations of the archetypal Seyfert galaxy, NGC 4151, performed over an 18-month period between early 1990 and mid-1991. The present program complements earlier extensive monitoring of this source in the medium-energy X-ray band by both EXOSAT and Ginga to give a combined data set of some 36 separate observations made over a period of 8 years. The new observations bring to light a remarkable transient change in the low-energy extinction and soft X-ray excess apparent in the X-ray spectrum of NGC 4151. The spectrum became systematically softer below about 4 keV from mid-1988, with the spectral softness peaking in mid-1990 and then reverting to its former state by late 1990. Interpreting this in terms of the partial covering model, the covered fraction of the source, which normally takes a value of 80-90 percent, underwent a sharp decline to about 20 percent over a 2-year period and then returned to the canonical level over the following six months. This observation favors the presence of a normally stable 'bulk' structure such as an edge-on accretion disk. A transitory change of azimuthal structure in the disk could then account for the apparent dip in the covered fraction. If the central X-ray source radiates isotropically then the medium producing the bulk of the iron-line emission must deviate from a spherically symmetric distribution.

Yaqoob, T.↗

NASA NTRS2003

The Human Sympathetic Nervous System Response to Spaceflight

The sympathetic nervous system is an important part of the autonomic (or automatic) nervous system. When an individual stands up, the sympathetic nervous system speeds the heart and constricts blood vessels to prevent a drop in blood pressure. A significant number of astronauts experience a drop in blood pressure when standing for prolonged periods after they return from spaceflight. Difficulty maintaining blood pressure with standing is also a daily problem for many patients. Indirect evidence available before the Neurolab mission suggested the problem in astronauts while in space might be due partially to reduced sympathetic nervous system activity. The purpose of this experiment was to identify whether sympathetic activity was reduced during spaceflight. Sympathetic nervous system activity can be determined in part by measuring heart rate, nerve activity going to blood vessels, and the release of the hormone norepinephrine into the blood. Norepinephrine is a neurotransmitter discharged from active sympathetic nerve terminals, so its rate of release can serve as a marker of sympathetic nervous system action. In addition to standard cardiovascular measurements (heart rate, blood pressure), we determined sympathetic nerve activity as well as norepinephrine release and clearance on four crewmembers on the Neurolab mission. Contrary to our expectation, the results demonstrated that the astronauts had mildly elevated resting sympathetic nervous system activity in space. Sympathetic nervous system responses to stresses that simulated the cardiovascular effects of standing (lower body negative pressure) were brisk both during and after spaceflight. We concluded that, in the astronauts tested, the activity and response of the sympathetic nervous system to cardiovascular stresses appeared intact and mildly elevated both during and after spaceflight. These changes returned to normal within a few days.

Ertl, Andrew C.↗

NASA NTRS2012

High-Performance Modeling and Simulation of Anchoring in Granular Media for NEO Applications

NASA is interested in designing a spacecraft capable of visiting a near-Earth object (NEO), performing experiments, and then returning safely. Certain periods of this mission would require the spacecraft to remain stationary relative to the NEO, in an environment characterized by very low gravity levels; such situations require an anchoring mechanism that is compact, easy to deploy, and upon mission completion, easy to remove. The design philosophy used in this task relies on the simulation capability of a high-performance multibody dynamics physics engine. On Earth, it is difficult to create low-gravity conditions, and testing in low-gravity environments, whether artificial or in space, can be costly and very difficult to achieve. Through simulation, the effect of gravity can be controlled with great accuracy, making it ideally suited to analyze the problem at hand. Using Chrono::Engine, a simulation pack age capable of utilizing massively parallel Graphic Processing Unit (GPU) hardware, several validation experiments were performed. Modeling of the regolith interaction has been carried out, after which the anchor penetration tests were performed and analyzed. The regolith was modeled by a granular medium composed of very large numbers of convex three-dimensional rigid bodies, subject to microgravity levels and interacting with each other with contact, friction, and cohesional forces. The multibody dynamics simulation approach used for simulating anchors penetrating a soil uses a differential variational inequality (DVI) methodology to solve the contact problem posed as a linear complementarity method (LCP). Implemented within a GPU processing environment, collision detection is greatly accelerated compared to traditional CPU (central processing unit)- based collision detection. Hence, systems of millions of particles interacting with complex dynamic systems can be efficiently analyzed, and design recommendations can be made in a much shorter time. The figure shows an example of this capability where the Brazil Nut problem is simulated: as the container full of granular material is vibrated, the large ball slowly moves upwards. This capability was expanded to account for anchors of different shapes and penetration velocities, interacting with granular soils.

Quadrelli, Marco B.↗