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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 sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Exercise and pharmacological countermeasures for bone loss during long-duration space flight

Bone loss in the lower extremities and lumbar spine is an established consequence of long-duration human space flight. Astronauts typically lose as much bone mass in the proximal femur in 1 month as postmenopausal women on Earth lose in 1 year. Pharmacological interventions have not been routinely used in space, and countermeasure programs have depended solely upon exercise. However, it is clear that the osteogenic stimulus from exercise has been inadequate to maintain bone mass, due to insufficient load or duration. Attention has therefore been focused on several pharmacological interventions that have been successful in preventing or attenuating osteoporosis on Earth. Anti-resorptives are the class of drugs most commonly used to treat osteoporosis in postmenopausal women, notably alendronate sodium, risedronate sodium, zoledronic acid, and selective estrogen receptor modulators, such as raloxifene. There has also been considerable recent interest in anabolic agents such as parathyroid hormone (PTH) and teriparatide (rhPTH [1-34]). Vitamin D and calcium supplementation have also been used. Recent studies of kindreds with abnormally high bone mineral density have provided insight into the genetic regulation of bone mass. This has led to potential therapeutic interventions based on the LRP5, Wnt and BMP2 pathways. Another target is the RANK-L/osteoprotegerin signaling pathway, which influences bone turnover by regulating osteoclast formation and maturation. Trials using such therapies in space are being planned. Among the factors to be considered are dose-response relationships, bone quality, post-use recovery, and combination therapies--all of which may have unique characteristics when the drugs are used in space.

NASA Discipline Musculoskeletal↗
NASA NTRS2014

Effects of Long Duration Spaceflight on Venous and Arterial Compliance

The visual impairment and intracranial pressure syndrome (VIIP) is a newly described space flight-associated medical condition made up of a constellation of symptoms affecting at least 34% of American astronauts who have flown International Space Station (ISS) missions. VIIP is defined primarily by visual acuity deficits and anatomical changes to eye structures, and is thought to be related to elevated intracranial pressure secondary to space flightinduced cephalad fluid shifts. Loss of visual acuity could be a significant threat to crew health and performance and may be suggestive of other adaptations with implications for years post-flight. Our primary objective is to determine whether vascular compliance is altered by space flight and whether such adaptations are related to the incidence of VIIP. In particular, we will measure ocular parameters and vascular compliance in vessels of the head and neck in astronauts who have no space flight experience, in astronauts before, during, and after space flight, and in bed rest subjects with conditions similar to space flight. Additionally, we will analyze astronaut data from the Lifetime Surveillance of Astronaut Health (LSAH) archive to determine which factors might be predictive of the development of VIIP. The project will be conducted in four separate but related parts. To understand the baseline condition of astronauts without any prior space flight experience, we will study 10 astronauts who have never flown in space by performing a comprehensive evaluation of the vasculature of the head, neck and eyes. Hemodynamic data (stroke volume and blood pressure), ocular (tonometry and ocular ultrasound), venous and arterial parameters will be acquired across a range of tilt angles (20, 10, 0, -10, -20 degrees). Vessels to be studied include the temporal, jugular, and vertebral veins and the cerebral, carotid and vertebral arteries. Ophthalmic data from the annual physical will be obtained through data sharing. To examine the relation between vascular compliance in the head and neck and the development of VIIP after a long duration space flight, we will study 10 astronauts before, during, and after long-duration ISS missions. Pre- and post-flight testing will be identical to that described above. During flight, images of the same vessels of interest will be obtained for later analysis. Ophthalmic data including VIIP scores will be obtained through data sharing from medically-required tests. To investigate the effects of age and elevated sodium intake, two potential contributors to VIIP, we will study 24 men (in two age groups: 25-35 and 45-55) during a 14 day 6deg head-down bed rest, a well-accepted analog of space flight. Standard NASA bed rest conditions will be maintained except for dietary sodium. Sodium intake will be similar to that of ISS astronauts, which is higher than consumed in previous bed rest studies. Pre- and post-bed rest testing procedures will be identical to the testing protocol described above for astronauts. Ophthalmic testing (optical coherence tomography, fundoscopy, and tonometry) will be conducted on the same day that vascular compliance measures are obtained. To identify parameters that may relate to an increase in an astronaut's susceptibility to developing VIIP, we will use data mining techniques to evaluate astronaut data obtained from the LSAH. Medical history, family history, space flight history and its related exposures, and history of high performance jet aircraft exposure will be examined for their potential relationship to ocular data. We hypothesize that the cephalad fluid shift induced by space flight will result in structural and functional adaptations in head and neck vessels leading to decreased vascular compliance and related to the development of VIIP symptoms. Further, although VIIP has not been observed in previous bed rest studies, we hypothesize that an elevated sodium intake will increase the incidence of VIIP symptoms in this space flight analog. Finally, we hypothesize that data mining analyses will reveal relationships between health history, previous exposures (including space flight and high performance aircraft), and the development of VIIP in the astronaut population.

Ribeiro, L. C.↗
NASA NTRS1976

Long Duration Exposure Facility - A multipurpose free-flying experiment carrier

The Long Duration Exposure Facility (LDEF) is being developed by NASA to accommodate, using the Space Shuttle, a class of technology, science and applications experiments which require a free-flying exposure in space, but which do not require a sophisticated or dedicated satellite. The facility is a simple reusable structure about 14 ft in diameter and 30 ft long, which is three-axis gravity-gradient stabilized when free flying in space. Various aspects of the LDEF are examined, including the attitude stabilization system, the experiment trays, the experiment exposure control canister,and the environment monitoring system. LDEF mission plans are considered, as is experiment selection - the space debris damage experiment, the thermal coating experiment, the solar cells and arrays experiment, and the active optical components experiment.

Kinard, W. H.↗
NASA NTRS2010

Vestibular-Somatosensory Convergence in Head Movement Control During Locomotion after Long-Duration Space Flight

Exposure to the microgravity conditions of space flight induces adaptive modification in the control of vestibular-mediated reflexive head movement during locomotion after space flight. Space flight causes astronauts to be exposed to somatosensory adaptation in both the vestibular and body load-sensing (BLS) systems. The goal of these studies was to examine the contributions of vestibular and BLS-mediated somatosensory influences on head movement control during locomotion after long-duration space flight. Subjects were asked to walk on a treadmill driven at 1.8 m/s while performing a visual acuity task. Data were collected using the same testing protocol from three independent subject groups; 1) normal subjects before and after exposure to 30 minutes of 40% bodyweight unloaded treadmill walking, 2) bilateral labyrinthine deficient (LD) patients and 3) astronauts who performed the protocol before and after long duration space flight. Motion data from head and trunk segmental motion data were obtained to calculate the angular head pitch (HP) movements during walking trials while subjects performed the visual task, to estimate the contributions of vestibular reflexive mechanisms in HP movements. Results showed that exposure to unloaded locomotion caused a significant increase in HP movements, whereas in the LD patients the HP movements were significantly decreased. Astronaut subjects results showed a heterogeneous response of both increases and decreases in the amplitude of HP movement. We infer that BLS-mediated somatosensory input centrally modulates vestibular input and can adaptively modify head-movement control during locomotion. Thus, space flight may cause a central adaptation mediated by the converging vestibular and body load-sensing somatosensory systems.

Mulavara, Ajitkumar↗
NASA NTRS2016

Gene Expression and Structural Skeletal Responses to Long-Duration Simulated Microgravity in Rats

Spaceflight has deleterious effects on skeletal structure and function, specifically causingprofound loss in bone mass, density, and strength, as well as changes in expression levels of genes related to oxidative stress [Hyeon et al., Smith et al.]. It is known that bone resorption remains elevated after spaceflight and that bone density and strength fail to recover completely even years following spaceflight [Smith et al., Carpenter et al.]. However, our current understanding of the signaling pathways and molecular mechanisms that control bone loss and that link oxidative stress, bone resorption, and mechanical unloading of skeletal tissue is incomplete. Here, we aim to examine skeletal responses to simulated long-duration spaceflight on bone loss using the ground-based hindlimb unloading (HU) model in adult (9 months old) male rats. We hypothesized that simulated microgravity leads to the temporal regulation of oxidative-defense genes and pro-osteoclastogenic factors, showing progression and eventual plateau during long-term unloading, and that transient changes at early timepoints in these pathways precede skeletal adaptations to long-duration unloading. We will identify oxidativestress and bone resorption-related changes using global gene expression analysis (Affymetrix arrays) for both acute (within 14 days) and long-term timepoints (90 days). We will also use quantitative PCR to examine changes in expression of genes related to oxidative metabolism (e.g. Nrf2, SOD-1), bone turnover (resorption and formation markers, e.g. TRAP, osteocalcin respectively, SOST), and osteoclastogenesis (e.g. RANKL, OPG) at both early and late timepoints. We will then use detailed microarchitectural and structural analysis through microcomputed tomography to relate gene expression changes with structural changes in bone, expecting that plateaus in gene expression correlate with long-term changes in bone microarchitecture.

Rael, Victoria E.↗
NASA NTRS1991

Initial results from Long Duration Exposure Facility (LDEF) postretrieval observations

Initial postretrieval observations of the Long Duration Exposure Facility and the 57 onboard experiments are reported in this paper. These observations have revealed that the facility and experiments, which had remained in space for 68 months prior to being retrieved in January 1990, can be used to generate 'gage block' type data to verify the existing models of the low earth orbit environments and if necessary, the data to correct errors in these existing models. The LDEF observations can also be used to update and revise the existing models used by spacecraft designers to predict the effects of long exposures in these environments on spacecraft materials and components.

Kinard, William H.↗
DOE OSTI2023

Long-Duration Energy Storage: Resiliency for Military Installations

This report provides a quantitative techno-economic analysis of a long-duration energy storage (LDES) technology, when coupled to on-base solar photovoltaics (PV), to meet the U.S. Department of Defense's (DoD's) 14-day requirement to sustain critical electric loads during a power outage and significantly reduce an installation's carbon footprint. The LDES modeled is Antora Energy's battery energy storage system (BESS). It is currently at a technology readiness level (TRL) of 7 and not ready for full-scale deployment. To support decisions on the value of near-term demonstrations, this analysis looked at the potential value of Antora Energy's BESS if deployed in the future.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2001

Effect of Long-Duration Spaceflight on Postural Control During Self-Generated Perturbations

This report is the first systematic evaluation of the effects of prolonged weightlessness on the bipedal postural control processes during self-generated perturbations produced by voluntary upper limb movements. Spaceflight impacts humans in a variety of ways, one of which is compromised postflight postural control. We examined the neuromuscular activation characteristics and center of pressure motion (COP) associated with arm movement of eight subjects who experienced long duration spaceflight (3-6 months) aboard the Mir space station. Surface electromyography (EMG), arm acceleration, and COP motion were collected while astronauts performed rapid unilateral shoulder flexions prior to and after spaceflight. Subjects displayed compromised postural control after flight as evidenced by modified peak-to-peak COP anterior-posterior and medio-lateral motion and COP pathlength relative to preflight values. These changes were associated with disrupted neuromuscular activation characteristics, particularly after the completion of arm acceleration (i.e. when subjects were attempting to maintain their upright posture). These findings suggest that although the subjects were able to assemble coordination modes that enabled them to generate rapid arm movements, the subtle control necessary to maintain bipedal equilibrium evident in their preflight performance is compromised after long duration spaceflight.

Layne, Charles S.↗
DOE OSTI2025

Long-Duration Energy Storage Grid Integration-Valuation Framework and Incentive Gaps

Given these challenges and current modeling gaps on Long Duration Energy Storage (LDES), enhancing the structure and design of existing planning, operations, and organized wholesale markets can better characterize the value of LDES to the power system. To more thoroughly assess the gaps and barriers to LDES investment and readiness for integration into a future grid, we conducted stakeholder outreach through an online survey, interviews with individual independent system operators/regional transmission organizations, and a literature review. Based on this assessment, we identified a set of opportunities for LDES focused development, including a framework to quantify the contributions of LDES on resource adequacy, reliability, and resiliency. Specifically, we identify the potential demand for and benefits of an open-source, LDES-centric evaluation framework that can guide future planning, operations, market design, and policy reforms.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1990

The role of the Long Duration Exposure Facility in the design of the Space Station Freedom

The Long Duration Exposure Facility (LDEF) satellite retrieved this year by the U.S. Space Shuttle offers spacecraft designers an unprecedented opportunity to examine synergistic, long-term space environmental effects on systems and materials. This paper discusses the strategy for data development and the role its implementation will play in the design of the Space Station Freedom. Examples are provided from three key areas (environments definition, protection of external surfaces, and verification of system components) to illustrate LDEF's potential contribution.

Little, S. A.↗
NASA NTRS1976

Long duration exposure facility - A multipurpose free-flying experiment carrier

The Long Duration Exposure Facility (LDEF) is being developed to accommodate, using the Shuttle, a class of technology, science, and applications experiments which do not require a sophisticated or dedicated satellite. The LDEF is a simple reusable structure approximately 4.3 m in diameter and 9 m in length. The basic LDEF consists of a structural framework whose cross section is a 12-sided regular polygon. A facility description is provided, taking into account the structure, aspects of attitude stabilization, the experiment trays, the experiment exposure control canister, the environment monitoring system, and Shuttle bay environment measurements. Missions and questions of experiment selection are discussed, giving attention to orbits, dynamic motions, a space debris damage experiment, thermal coating experiments, the solar cells and arrays experiment, and the active optical components experiment.

Kinard, W. H.↗
NASA NTRS1980

Vibration analysis of the Long Duration Exposure Facility (LDEF) using SPAR

The structural modeling of the Long Duration Exposure Facility (LDEF) utilizing the SPAR system of computer programs for vibration analysis is discussed. The technical areas of interest were: (1) development of the LDEF finite element model; (2) derivation of tray effective panel stiffness matrix using finite element tray models; (3) assessment of attachment conditions and end fitting flexibility by comparing SPAR with test static displacements; (4) SPAR grouping; and (5) derivation of the LDEF frequencies and mode shapes and comparing them with tests. Special detailed finite element modeling was required to obtain good agreement between analytical and test vibration modes. An orthotropic panel in the overall model was developed. Orthotropic stiffness for this panel were obtained from finely detailed statically loaded SPAR models which included stiffness and allowed for partial relative sliding of the tray clamping attachments. Sensitivity to LDEF joint boundary conditions was determined, and static test data proved valuable in assessing modeling of local end fittings.

Edighoffer, H.↗
NASA NTRS1984

Investigation of the effects of long-duration exposure on active optical system components (S0050)

The effects of long duration space exposure on the relevant performance parameters of lasers, radiation detectors, and selected optical components, was determined. The results and implications of the measurements indicating real or suspected degradation mechanisms were evaluated and guidelines, based on these results, for selection and use of components for space electro-optical systems are established.

Blue, M. D.↗
NASA NTRS1991

The use of membranes in life support systems for long-duration space missions

The use of membrane processes in a long-duration manned mission's regenerative environmental control and life-support system is presently discussed, in the cases of treatment for hygiene water, urine, humidity condensate, and phase-change distillate, as well as of water-vapor and CO2 removal from spacecraft air. Attention is given to the design of a tube-side-feed hollow-fiber module for membrane support and fluids-feed, as well as to the schematics for a membrane-based urine processor, an air recirculator, a potable-water producer, and a two-stage urine treater.

Mccray, S. B.↗
NASA NTRS2005

Status of the NEXT Ion Thruster Long Duration Test

The status of NASA's Evolutionary Xenon Thruster (NEXT) Long Duration Test (LDT) is presented. The test will be conducted with a 36 cm diameter engineering model ion thruster, designated EM3, to validate and qualify the NEXT thruster propellant throughput capability of 450 kg xenon. The ion thruster will be operated at various input powers from the NEXT throttle table. Pretest performance assessments demonstrated that EM3 satisfies all thruster performance requirements. As of June 26, 2005, the ion thruster has accumulated 493 hours of operation and processed 10.2 kg of xenon at a thruster input power of 6.9 kW. Overall ion thruster performance, which includes thrust, thruster input power, specific impulse, and thrust efficiency, has been steady to date with very little variation in performance parameters.

Frandina, Michael M.↗