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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

International Space Station Acoustics – A Status Report

It is important to control acoustic noise aboard the International Space Station (ISS) to provide a satisfactory environment for voice communications, alarm audibility, and restful sleep, and to minimize the risk for hearing loss. Acoustic monitoring is an important part of the noise control process on ISS, providing critical data for trend analysis, noise exposure analysis, validation of acoustic analyses and predictions, and to provide strong evidence for ensuring crew health and safety, thus allowing Flight Certification. And since the primary noise sources on ISS include the environmental control and life support system’s air revitalization system (fans and airflow) and active thermal control system (pumps and water flow), acoustic monitoring will indicate changes in hardware noise emissions that may indicate system degradation or performance issues. This paper provides the current acoustic levels in the ISS modules and sleep stations, and is an update to the status presented in 2018. Since this last status report, noise levels have remained consistent, but issues with stalled fan noise and unexplained low frequency spectral peaks have caused some exceedances to requirements. Noise levels in the Russian Segment have either remained consistent or have been reduced slightly, except for the new Multipurpose Laboratory Module, which has some significant noise exceedances.

Christopher S Allen↗
NASA NTRS2001

Consequences of contamination of the spacecraft environment: immunologic consequences

Long-term space voyages pose numerous known and unknown health hazards, to the human immune system. Well-studied clinical examples of secondary immunodeficiencies created on Earth, lead one to predict that the conditions of prolonged space flight would weaken the human immune responses that normally hold infection and cancer in check. From evidence gathered from humans flown for prolonged periods in space and from human models of space flight studied on Earth it is reasonable to suspect that space travelers to the planet Mars would experience a weakening of immunity. Subtle defects of immune cell structure and function have been observed in astronauts, such as weakening of specific T-lymphocyte recall of specific antigens. Ground-based models also have demonstrated alterations of immune function, such as the elevation of neuroendocrine immune system messengers, interleukin-6, and soluble tumor necrosis factor-alpha receptor in sleep deprivation. Since severe immune compromise the clinical consequences of reactivation of latent virus infections and the development of cancer, has yet to be seen in space flight or in the Earth models, it is extremely important to begin to quantify early changes in immunity to predict the development of immune system collapse with poor clinical outcomes. This approach is designed to validate a number of surrogate markers that will predict trouble ahead. Inherent in this research is the development of countermeasures to reduce the risks of infection and cancer in the first humans going to Mars.

Non-NASA Center↗
NASA NTRS1998

Scaling and universality in heart rate variability distributions

We find that a universal homogeneous scaling form describes the distribution of cardiac variations for a group of healthy subjects, which is stable over a wide range of time scales. However, a similar scaling function does not exist for a group with a common cardiopulmonary instability associated with sleep apnea. Subtle differences in the distributions for the day- and night-phase dynamics for healthy subjects are detected.

NASA Discipline Cardiopulmonary↗
NASA NTRS1999

Stability, precision, and near-24-hour period of the human circadian pacemaker

Regulation of circadian period in humans was thought to differ from that of other species, with the period of the activity rhythm reported to range from 13 to 65 hours (median 25.2 hours) and the period of the body temperature rhythm reported to average 25 hours in adulthood, and to shorten with age. However, those observations were based on studies of humans exposed to light levels sufficient to confound circadian period estimation. Precise estimation of the periods of the endogenous circadian rhythms of melatonin, core body temperature, and cortisol in healthy young and older individuals living in carefully controlled lighting conditions has now revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both age groups, with a tight distribution consistent with other species. These findings have important implications for understanding the pathophysiology of disrupted sleep in older people.

NASA Discipline Regulatory Physiology↗
NASA NTRS1993

Performance and mood-state parameters during 30-day 6 degrees head-down bed rest with exercise training

The study was designed to determine if performance and mood impairments occur in bed-rested subjects, and if different exercise-training regimens modify or prevent them. Eighteen normal, healthy men were divided on the basis of age, peak oxygen uptake, and maximal isometric knee extension strength into three similar groups: no exercise (NOE), isotonic exercise (ITE), and isokinetic exercise (IKE). A 15-min battery of 10 performance tests and 8 mood and 2 sleep scales were administered daily during ambulatory control, 30 d of absolute bed rest (BR), and 4 d of ambulatory recovery. Performance test proficiency increased (p < 0.05) for all three groups during BR in 7 of 10 tests and there were no consistent significant differences between the three groups. However, during BR, the ITE group was distinguished from the other groups by a decline (p < 0.05) in the activation mood dimension and in two of its constituent scales (motivation and concentration), and by improvement (p < 0.05) in the trouble-falling-asleep and psychological-tension scales. Since few deleterious changes in performance and mood occurred in the three groups and did not exceed baseline ambulatory levels, we conclude that mood and performance did not deteriorate in response to prolonged BR and were not altered by exercise training. However, the decline in activation mood scales in the ITE group may reflect overtraining or excess total workload in this group.

NASA Center ARC↗
NASA NTRS2017

Psychomotor Vigilance Task Evaluation for Touchscreen Devices

The Psychomotor Vigilance Task (PVT) is considered the gold standard fatigue detection device and is used frequently in fatigue research. The purpose of this study was to compare a psychomotor vigilance task developed for use on touchscreen devices with the original PVT-192 in conditions of acute sleep loss and circadian desynchronization. Participants arrived in the lab approximately two hours after their habitual time and were asked to stay awake for up to 24 hrs and take 5-minute reaction time tests every 2 hours on two different devices: the original PVT-192 and NASA-PVT on an iPod. We found that the NASA-PVT and PVT-192 were sensitive to the 24 hrs of extended wakefulness.

sleep loss↗
NASA NTRS2017

Oculomotor Behavior Metrics Change According to Circadian Phase and Time Awake

There is a need for non-invasive, objective measures to forecast performance impairment arising from sleep loss and circadian misalignment, particularly in safety-sensitive occupations. Eye-tracking devices have been used in some operational scenarios, but such devices typically focus on eyelid closures and slow rolling eye movements and are susceptible to the intrusion of head movement artifacts. We hypothesized that an expanded suite of oculomotor behavior metrics, collected during a visual tracking task, would change according to circadian phase and time awake, and could be used as a marker of performance impairment.

sleep deprivation↗
NASA NTRS2016

Fatigue Monitoring in Scheduled Airline Operations

Reporting and monitoring are important facets of a comprehensive Fatigue Risk Management System. As part of efforts to reduce fatigue risks, we partnered with an international airline to study 44 (4 Female) volunteer pilots over a 4 week period that included baseline earlymiddaylate flight days and rest days off. All study procedures were approved by an IRB and participants provided written informed consent prior to beginning the study. Reduced sleep duration was associated with both early and late duties. Performance was influenced by duty timing, time of day and time awake. TLX ratings were highest for mental and effort demands, while ATC and weather were the most identified hassle factors. Melatonin analysis revealed individual variations in circadian shift over the study period. The study results highlight the value of FRMS monitoring in airline operations. Ongoing crew education should emphasize individual variation and effective mitigation strategies. Further study could focus on workload and time of day scheduling factors.

sleep loss↗
NASA NTRS2022

Light in Ecological Settings: Entrainment, Circadian Disruption, and Interventions

Light is the predominant signal for the human circadian clock to synchronize to the solar 24-h day through an active process called entrainment. Modern light profiles are characterized by exposure to both natural daylight and artificial lighting. A mismatch between these self-selected light profiles and the solar day-night alternation can disrupt the circadian system, resulting in acute and chronic effects for health and safety. In this chapter, we describe (i) how entrainment works in the real world, illustrating the major role of light for this process; (ii) ways in which the circadian system can be disrupted by (external) factors such as irregular sleep, shift work, daylight saving time, and longitudinal position in a time zone; and (iii) how field studies have used light interventions to reduce direct and indirect effects of circadian disruption in ecological settings.

light interventions↗
NASA NTRS1965

Circadian rhythms in man.

Effect of isolation from external time cues on human circadian rhythms such as body temperature, sleeping period, passage of time estimation and urine excretion

HUMAN REACTION↗
NASA NTRS1969

Apollo 7 to 11 - Medical Concerns and Results

The goal of the Apollo Program is to land men on the moon and safely return them to earth. The medical task thus outlined required confirmation of the Gemini findings and definition and solution of any problems encountered in the four Apollo flights prior to the Apollo 11 lunar landing. The medical concerns included the following: 1. The effect of decreased red blood cell mass and decreased exercise capacity and of cardiovascular de conditioning on the ability of the crew to do lunar-surface activity; 2. The capability to work effectively in one-sixth the force of gravity and the energy cost of such work; 3. The ability to get adequate rest and sleep in flight and on the lunar surface; 4. The prevention of preflight, inflight, and post-flight illness by proper preventive medicine; 5. The possible development of motion sickness of vestibular origin; 6. The conduct of a post-flight quarantine of crew and lunar samples. The results of the Apollo 7 to 11 missions, demonstrating the ability of man to handle this difficult task and the environment successfully, are discussed in detail and are related to the future of manned flight.

Berry, C. A.↗