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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
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Issues on human acceleration tolerance after long-duration space flights

This report reviewed the literature on human tolerance to acceleration at 1 G and changes in tolerance after exposure to hypogravic fields. It was found that human tolerance decreased after exposure to hypokinetic and hypogravic fields, but the magnitude of such reduction ranged from 0 to 30 percent for plateau G forces and 30 to 70 percent for time tolerance on sustained G forces. A logistic regression model of the probability of individuals with 25 percent reduction in +Gz tolerance after 1 to 41 days of hypogravic exposures was constructed. The estimated values from the model showed a good correlation with the observed data. A brief review of the need for in-flight centrifuge during long-duration missions was also presented. Review of the available data showed that the use of countermeasures (such as anti-G suits, periodic acceleration, and exercise) reduced the decrement in acceleration tolerance after long-duration space flights. Areas of further research include quantification of the effect of countermeasures on tolerance, and methods to augment tolerance during and after exposures to hypogravic fields. Such data are essential for planning long-duration human missions.

Kumar, K. Vasantha↗
NASA NTRS1993

Rain rate duration statistics derived from the Mid-Atlantic coast rain gauge network

A rain gauge network comprised of 10 tipping bucket rain gauges located in the Mid-Atlantic coast of the United States has been in continuous operation since June 1, 1986. Rain rate distributions and estimated slant path fade distributions at 20 GHz and 30 GHz covering the first five year period were derived from the gauge network measurements, and these results were described by Goldhirsh. In this effort, rain rate time duration statistics are presented. The rain duration statistics are of interest for better understanding the physical nature of precipitation and to present a data base which may be used by modelers to convert to slant path fade duration statistics. Such statistics are important for better assessing optimal coding procedures over defined bandwidths.

Goldhirsh, Julius↗
NASA NTRS1995

Space Station as a Long Duration Exposure Facility

There is need for a space platform for experiments investigating long duration exposure to space. This platform should be maintainable in the event of a malfunction, and experiments should be easily recoverable for analysis on Earth. The International Space Station provides such a platform. The current Space Station configuration has six external experiment attachment sites, providing utilities and data support distributed along the external truss. There are also other sites that could potentially support long duration exposure experiments. This paper describes the resources provided to payloads at these sites, and cites examples of integration of proposed long duration exposure experiments on these sites. The environments to which external attached payloads will be exposed are summarized.

Folley, Adrienne↗
NASA NTRS1996

Fibre Size and Capillary Supply in Human M.vastus Lateralis after Long-Duration Spaceflight: Effects of Countermeasure Exercise Training

Muscle fiber atrophy is shown to be induced in human m.vastus lateralis even during short duration spaceflight. A study carried out to evaluate the effects of long duration spaceflight on human skeletal muscle fiber characteristics is reported on. Muscle fiber size and capillary supply were measured in samples obtained from the m.vastus lateralis of astronauts before and after a long duration flight. Most of the astronauts performed more than 80 percent of the recommended exercise training loads in terms of volume and intensity. Very slight fiber changes were found in fiber size and muscle capillary supply indices. It is concluded that the main factor which maintained fiber characteristics in the astronauts was the exercise measures taken by them.

Shenkman, Boris S.↗
NASA NTRS1998

Magnetic Field Configuration of Active Region NOAA 6555 at the Time of a Long Duration Flare on 23 March 1991: An Exception to Standard Flare Reconnection Model

The high-resolution H(sub alpha) images observed during the decay phase of a long duration flare on 23 March 1991 are used to study the three-dimensional magnetic field configuration of the active region NOAA 6555. Whereas, all the large flares in NOAA 6555 occurred at the location of high magnetic shear and flux emergence, this long duration flare was observed in the region of low magnetic shear at the photosphere. The H(sub alpha) loop activity started soon after the maximum phase of the flare. There were few long loop at the initial phase of the activity. Some of these were sheared in the chromosphere at an angle of about 45 deg with the east-west axis. Gradually, increasing number of shorter loops, oriented along the east-west axis, started appearing. The chromospheric Dopplergrams show blue-shifts at the end points of the loops. By using different magnetic field models, we have extrapolated the photospheric magnetograms to the chromospheric heights. The magnetic field lines computed by using the potential field model correspond to most of the observed H(sub alpha) loops. The height of the H(sub alpha) loops were derived by comparing them with the computed field lines. From the temporal evolution of the H(sub alpha) loop activity, we derive the negative rate of appearance of H(sub alpha) features as a function of height. It is found that the field lines oriented along one of the neutral lines was sheared and low lying. The higher field lines were mostly potential. The paper also outlines a possible scenario for describing the post-flare stage of the observed long duration flare.

Choudhary, Debi Prasad↗
NASA NTRS1999

Head and Trunk Movement Control During Locomotion After Long-Duration Spaceflight

Exposure to the microgravity environment encountered during spaceflight induces adaptive alteration in sensorimotor function that leads to postflight disturbances in locomotor control. Head and trunk movement control plays a central role in maintaining gaze stability and in providing a stable reference system to permit spatial navigation in a complex and constantly varying environment. The goal of the present study was to investigate the effects of long-duration spaceflight (3-6 months) on head and trunk movement control during postflight terrestrial locomotion. Before and after spaceflight, subjects walked on a motorized treadmill while performing a challenging gaze stabilization task requiring number recognition. Head and trunk kinematic data were collected with a video-based motion analysis system. Analysis of roll, pitch and yaw head and trunk movements during treadmill walking revealed postflight alterations in head and trunk movement control in all three planes of motion. Subjects also experienced oscillopsia during postflight walking which led to impairment in performance of the number recognition task. These data indicate that exposure to long-duration space flight causes alteration in head and trunk movement control during postflight locomotion. These changes have implications for the control of gaze and maintenance of dynamic stability during walking after long-duration spaceflight.

Bloomberg, Jacob J.↗
NASA NTRS1998

Psychological and Behavioral Health Issues of Long-Duration Space Missions

It will be the responsibility of the long-duration space flight crew to take the actions necessary to maintain their health and well-being and to cope with medical emergencies without direct assistance from support personnel, including maintaining mental health and managing physiological and psychological changes that may impair decision making and performance. The Behavior and Performance Integrated Product Team at Johnson Space Center, working, within the Space Medicine, Monitoring, and Countermeasures Program, has identified critical questions pertaining to long-duration space crew behavioral health, psychological adaptation, human factors and habitability, and sleep and circadian rhythms. Among the projects addressing these questions are: the development of tools to assess cognitive functions during space missions; the development of a model of psychological adaptation in isolated and confined environments; tools and methods for selecting individuals and teams well-suited for long-duration missions; identification of mission-critical tasks and performance evaluation; and measures of sleep quality and correlation to mission performance.

Eksuzian, Daniel J.↗
NASA NTRS2003

The Case for Durative Actions: A Commentary on PDDL2.1

The addition of durative actions to PDDL2.1 sparked some controversy. Fox and Long argued that actions should be considered as instantaneous, but can start and stop processes. Ultimately, a limited notion of durative actions was incorporated into the language. I argue that this notion is impoverished, and that the underlying philosophical position of regarding durative actions as being a shorthand for a start action, process, and stop action ignores the realities of modelling and execution for complex systems.

Smith, David E.↗
NASA NTRS2003

Physiology, medicine, long-duration space flight and the NSBRI

The hazards of long-duration space flight are real and unacceptable. In order for humans to participate effectively in long-duration orbital missions or continue the exploration of space, we must first secure the health of the astronaut and the success of such missions by assessing in detail the biomedical risks of space flight and developing countermeasures to these hazards. Acquiring the understanding necessary for building a sound foundation for countermeasure development requires an integrated approach to research in physiology and medicine and a level of cooperative action uncommon in the biomedical sciences. The research program of the National Space Biomedical Research Institute (NSBRI) was designed to accomplish just such an integrated research goal, ameliorating or eliminating the biomedical risks of long-duration space flight and enabling safe and productive exploration of space. The fruits of these labors are not limited to the space program. We can also use the gained understanding of the effects and mechanisms of the physiological changes engendered in space and the applied preventive and rehabilitative methods developed to combat these changes to the benefit of those on Earth who are facing similar physiological and psychological difficulties. This paper will discuss the innovative approach the NSBRI has taken to integrated research management and will present some of the successes of this approach. c2003 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.

NASA Discipline General Space Life Sciences↗
NASA NTRS2002

Planning strategies for development of effective exercise and nutrition countermeasures for long-duration space flight

Exercise and nutrition represent primary countermeasures used during space flight to maintain or restore maximal aerobic capacity, musculoskeletal structure, and orthostatic function. However, no single exercise, dietary regimen, or combination of prescriptions has proven entirely effective in maintaining or restoring cardiovascular and musculoskeletal functions to preflight levels after prolonged space flight. As human space flight exposures increase in duration, identification, assessment, and development of various effective exercise- and nutrition-based protective procedures will become paramount. The application of adequate dietary intake in combination with effective exercise prescription will be based on identification of basic physiologic stimuli that maintain normal function in terrestrial gravity, and understanding how specific combinations of exercise characteristics (e.g., duration, frequency, intensity, and mode) can be combined with minimal nutritional requirements that mimic the stimuli normally produced by living in Earth's gravity environment. This can be accomplished only with greater emphasis of research on ground-based experiments targeted at understanding the interactions between caloric intake and expenditure during space flight. Future strategies for application of nutrition and exercise countermeasures for long-duration space missions must be directed to minimizing crew time and the impact on life-support resources.

Review↗
NASA NTRS2005

Long-Duration Testing of a Temperature-Swing Adsorption Compressor for Carbon Dioxide for Closed-Loop Air Revitalization Systems

This paper describes the results of long-duration testing of a temperature-swing adsorption compressor that has application in the International Space Station (ISS) and future spacecraft for closing the air revitalization loop. The air revitalization system of the ISS operates in an open loop mode and relies on the resupply of oxygen and other consumables from Earth for the life support of astronauts. A compressor is required for delivering the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and thereby closing the air-loop. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver at a higher pressure as required by a processor. The TSAC is an ideal interface device for CO2 removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. The TSAC was developed and its operation was successfully verified in integration tests with the flight-like Carbon Dioxide Removal Assembly (CDRA) at Marshall Space Flight Center prior to the long-duration tests. Long-duration tests reveal the impacts of repeated thermal cycling on the compressor components and the adsorbent material.

Rosen, Micha↗
NASA NTRS2006

Evaluation of Long Duration Flight on Venus

An analysis was performed to evaluate the potential of utilizing either an airship or aircraft as a flight platform for long duration flight within the atmosphere of Venus. In order to achieve long-duration flight, the power system for the vehicle had to be capable of operating for extended periods of time. To accomplish these, two types of power systems were considered, a solar energy-based power system utilizing a photovoltaic array as the main power source and a radioisotope heat source power system utilizing a Stirling engine as the heat conversion device. Both types of vehicles and power systems were analyzed to determine their flight altitude range. This analysis was performed for a station-keeping mission where the vehicle had to maintain a flight over a location on the ground. This requires the vehicle to be capable of flying faster than the wind speed at a particular altitude. An analysis was also performed to evaluate the altitude range and maximum duration for a vehicle that was not required to maintain station over a specified location. The results of the analysis show that each type of flight vehicle and power system was capable of flight within certain portions of Venus s atmosphere. The aircraft, both solar and radioisotope power proved to be the most versatile and provided the greatest range of coverage both for station-keeping and non-station-keeping missions.

Landis, Geoffrey A.↗
NASA NTRS2007

Recovery of Spaceflight-induced Bone Loss: Bone Mineral Density after Long-Duration Missions as Fitted with an Exponential Function

The loss of bone mineral in NASA astronauts during spaceflight has been investigated throughout the more than 40 years of space travel. Consequently, it is a medical requirement at NASA Johnson Space Center (JSC) that changes in bone mass be monitored in crew members by measuring bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) before and after flight on astronauts who serve on long-duration missions (4-6 months). We evaluated this repository of medical data to track whether there is recovery of bone mineral that was lost during spaceflight. Our analysis was supplemented by BMD data from cosmonauts ( by convention, a space traveler formally employed by the Russia Aviation and Space Agency or by the previous Soviet Union) who had also flown on long-duration missions. Data from a total of 45 individual crew members -- a small number of whom flew on more than one mission -- were used in this analysis. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing). Plotted BMD changes were fitted to an exponential mathematical function that estimated: i) BMD change on landing day (day 0) and ii) the number of days after landing when 50% of the lost bone would be recovered ("50% recovery time") in the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. In sum, averaged losses of bone mineral after long-duration spaceflight ranged between 2-9% across all sites with our recovery model predicting a 50% restoration of bone loss for all sites to be within 9 months.

Sibonga, J. D.↗
NASA NTRS2006

Determination of Spring Onset and Growing Season Duration using Satellite Measurements

An integrated approach to retrieve microwave emissivity difference vegetation index (EDVI) over land regions has been developed from combined multi-platform/multi-sensor satellite measurements, including SSM/I measurements. A possible relationship of the remotely sensed EDVI and the leaf physiology of canopy is exploited at the Harvard Forest site for two growing seasons. This study finds that the EDVI is sensitive to leaf development through vegetation water content of the crown layer of the forest canopy, and has demonstrated that the spring onset and growing season duration can be determined accurately from the time series of satellite estimated EDVI within uncertainties about 3 and 7 days for spring onsets and growing season duration, respectively, compared to in-situ observations. The leaf growing stage may also be quantitatively monitored by a normalized EDVI. Since EDVI retrievals from satellite are generally possible during both daytime and nighttime under non-rain conditions, the EDVI technique studied here may provide higher temporal resolution observations for monitoring the onset of spring and the duration of growing season compared to currently operational satellite methods.

Min, Q.↗
NASA NTRS2007

GRB 060505: A Possible Short-Duration Gamma-Ray Burst in a Star Forming Region at Redshift of 0.09

On May 5, 2006 a four-second duration, low-energy, approximately 10(exp 59) erg, Gamma-Ray Burst (GRB) was observed, spatially associated with a z=0.0894 galaxy. Here, we report the discovery of the GRB optical afterglow and observations of its environment using gemini-south, Hubble Space Telescope (HST), Chandra, Swift and the Very Large Array. The optical afterglow of this GRB is spatially associated with a prominent star forming region in the Sc-type galaxy 2dFGRS S173Z112. Its proximity to a star forming region suggests that the progenitor delay time, from birth to explosion, is smaller than about 10 Myr. Our HST deep imaging rules out the presence of a supernova brighter than an absolute magnitude of about -11 (or -126 in case of 'maximal' extinction) at about two weeks after the burst, and limits the ejected mass of radioactive Nickel 56 to be less than about 2x10(exp -4) solar mass (assuming no extinction). Although it was suggested that GRB 060505 may belong to a new class of long-duration GRBs with no supernova, we argue that the simplest interpretation is that the physical mechanism for this burst is the same as for short-duration GRBs.

Ofek, E. O.↗
NASA NTRS2009

The Duration of Chemical Weathering of Gusev Crater's Wishstone-Watchtower Sequence

Mineralogical abundance of primary minerals versus secondary minerals, chemical mixing relationships, and elemental ratios have been used to assess the degree of aqueous alteration at Gusev Crater and Meridiani Planum. However, limited work has used Ti-normalized mass-balance analysis chemical data to quantify gains and losses of elements from altered materials as well as estimate the duration of aqueous alteration on Mars. The Ti-normalized mass-balance approach accounts for volumetric changes associated with geochemical alteration. If volumetric changes are not considered, observed geochemical trends based on un-normalized data have the potential to be misleading. Assessing gains and losses from altered materials can indicate the geochemistry of fluids involved in the alteration. Furthermore, elemental losses can be combined with dissolution rates to estimate the duration of chemical weathering. Knowledge of the duration of aqueous alteration will provide insight into the climate history of Mars as well as indicate the potential for microbial habitability. The Wishstone-Watchtower materials in Gusev Crater are suitable candidates for Ti-normalized mass-balance analysis because mixing relationships of these two materials indicate that Watchtower materials may be derived from Wishstone-like materials. The objectives of this work are to (1) employ Ti-normalized mass-balance to assess gains and losses from the Wishstone-Watchtower sequence and (2) to combine losses with laboratory dissolution rates to estimate alteration times of the Watchtower material.

Sutter, Brad↗
NASA NTRS2010

Data Mining Activity for Bone Discipline: Calculating a Factor of Risk for Hip Fracture in Long-Duration Astronauts

The factor-of-risk (Phi), defined as the ratio of applied load to bone strength, is a biomechanical approach to hip fracture risk assessment that may be used to identify subjects who are at increased risk for fracture. The purpose of this project was to calculate the factor of risk in long duration astronauts after return from a mission on the International Space Station (ISS), which is typically 6 months in duration. The load applied to the hip was calculated for a sideways fall from standing height based on the individual height and weight of the astronauts. The soft tissue thickness overlying the greater trochanter was measured from the DXA whole body scans and used to estimate attenuation of the impact force provided by soft tissues overlying the hip. Femoral strength was estimated from femoral areal bone mineral density (aBMD) measurements by dual-energy x-ray absorptiometry (DXA), which were performed between 5-32 days of landing. All long-duration NASA astronauts from Expedition 1 to 18 were included in this study, where repeat flyers were treated as separate subjects. Male astronauts (n=20) had a significantly higher factor of risk for hip fracture Phi than females (n=5), with preflight values of 0.83+/-0.11 and 0.36+/-0.07, respectively, but there was no significant difference between preflight and postflight Phi (Figure 1). Femoral aBMD measurements were not found to be significantly different between men and women. Three men and no women exceeded the theoretical fracture threshold of Phi=1 immediately postflight, indicating that they would likely suffer a hip fracture if they were to experience a sideways fall with impact to the greater trochanter. These data suggest that male astronauts may be at greater risk for hip fracture than women following spaceflight, primarily due to relatively less soft tissue thickness and subsequently greater impact force.

Ellman, R.↗
NASA NTRS2002

Neurovestibular Effects of Long-Duration Spaceflight: A Summary of Mir-Phase 1 Experiences

Space motion sickness and associated neurovestibular dysfunction though not completely understood - have been relatively well clinically and operationally characterized on short-duration (1-2 week) Space Shuttle missions (Oman, et al, 1984, 1986; Thornton, et al, 1987; Reschke, et al, 1994). Between March 1995 and June 1998, seven NASA astronauts flew on the Russian Mir space station, as "Phase 1" of the joint effort to build the International Space Station, and provided NASA with invaluable experience on the operational and biomedical problems associated with flights of up to six months in duration. The goal of this paper is to provide a summary of the available information on neurovestibular dysfunction, space motion sickness, and readaptation to Earth's gravity on the NASA Mir flights, based on a set of medical questionnaire data, transcripts, and interviews which are available from the NASA-Mir Phase I program. Records were incomplete and anecdotal. All references to specific crewmembers have been removed, to respect their individual privacy. Material was excerpted from multiple sources of information relating to neurologic function, sensory illusions and motion sickness of NASA-Mir Phase I Program crewmembers. Data were compiled by epoch (in-flight vs landing/postflight) and grouped by neurovestibular topic. The information was recorded either contemporaneously during or within days after landing, or retrospectively weeks to months later. Space motion sickness symptoms are more intense and longer in duration. Sense of spatial orientation takes at least a month to become "natural and instinctive" in space station structures, but mental survey knowledge is apparently not completely developed even after 3 months in some cases. Visual reorientation illusions (VRI) are more easily induced after long exposure to weightlessness. Head movements can cause illusory spinning sensations for up to 7 days postflight. Postural and balance control does not fully recover for at least a month postflight.

Richards, Jason T.↗