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PubMedDate not supplied

[Sensitivity of the respiratory regulatory apparatus to CO2 under simulated space flight conditions].

Using the rebreathing method, CO2 sensitivity of the respiration regulation system was investigated during a year-long enclosure study and head-down tilt tests of varying duration (up to 120 days). During the exposures CO2 and H+ were built up in the body. In the course of the enclosure study CO2 sensitivity was reduced. During bed rest experiments this parameter changed differently: it increased on day 7 and significantly decreased on days 55 to 100. These findings show that respiration regulation may vary markedly and indicate that it is worthwhile to carry out similar investigations in an actual space flight.

Adult↗
PubMedDate not supplied

[Dehydration therapy in human exposure to simulated space flight factors].

The effect of intravenous injections of 20% mannitol in a dose of 1 g per kg of body weight at a rate of 5 ml/min on the central circulation and cardiac contractile function was investigated. The infusions were performed to 18 healthy male volunteers, who participated in a head-down tilt test at -8 degrees, during the control period, on days 3, 7 and 14 of bed rest, and during the recovery. It was found that the prolonged osmo-therapy produced a clinically distinct dehydration effect without influencing central circulation. The therapy also led to positive cardiodynamics which was indicative of a decrease of the heart unproductive work and an improvement of left ventricle contractile function.

Adult↗
PubMed1993

Epidemiology of decompression sickness under simulated space extravehicular activities.

Several ground-based trials were conducted by NASA at the Lyndon B. Johnson Space Center, Houston, TX, during 1982-90 to examine the risk of altitude decompression sickness (DCS) during space extravehicular activities. There were 22 different pressure profiles involving single and staged decompression procedures, each lasting from 180 to 360 min at the final altitude. A total of 164 healthy subjects participated in 426 exposures to altitude. Symptoms of DCS occurred in 17% (74/426) and circulating microbubbles by precordial Doppler ultrasound were detected in 42% (179/426) of all exposures. About 27% (20/74) of exposures with symptoms resulted in test abort, and one-third of all test aborts required treatment in the hyperbaric chamber. There was about 3.20 times (95% Confidence Interval [95% CI] = 1.56-6.66) higher risk of symptoms in the presence of Doppler-detectable microbubbles. Examination of individual risk factors showed that there was about 4.3 times (95% CI = 1.62-11.50) higher risk of symptoms with increasing number of exposures. These findings emphasize the importance of evaluating risk factors from ground-based trials for application in operational decision-making and treatment strategies.

Adult↗
PubMed2001

Crew tension during a space station simulation.

Two space simulation studies for the European Space Agency found that interpersonal tension increased in the beginning, around the middle, and toward the end of the confinement. This article reports data from a third study where this issue was further examined. Three subjects were confined in the MIR space station simulator in Moscow for 135 days. Communication analysis, peer rating, questionnaires, and interviews were used to assess crew tension. The temporal pattern found in this study corresponds to the previous findings. The beginning of the period was characterized by competition over leadership. Decreased crew cohesion and aggression toward the mission control marked the middle of the confinement. In the final weeks, open conflicts emerged, and one member was socially excluded. Joking occurred frequently in the first half of the confinement, whereas negative emotional expressions increased in the second half. These results might assist planners in anticipating behavioral problems during space missions.

Adult↗
PubMed1999

Multiple-task performance on a computer-simulated life support system during a space mission simulation.

This paper presents an experiment which examined the effects of isolation and confinement during a simulation of a short-term space mission. During the 7-day spaceflight simulation, four Canadian astronauts were tested daily on a 30-min performance task. The task, CAMS (Cabin Air Management System), represents a computer-based simulation of a generic life support system. As a multiple-task environment, it allows the measurement of a wide range of task management variables such as primary and secondary task performance, and system control activities. Measures of subjective state variables were also taken. The results did not show any evidence of serious performance decrements for any crew member. The analysis revealed different adjustment patterns with which crew members responded as a function of mission duration and variations in workload. Among the secondary tasks employed, prospective memory was found to be more sensitive than reaction time to increases in workload. The paper concludes with a discussion of the utility of spaceflight simulations and computer-based simulations of space work.

Adaptation, Psychological↗
PubMed2004

Hearing and performance during a 70-h exposure to noise simulating the space station environment.

INTRODUCTION: Elevated hearing thresholds have been documented in some astronauts after long-term spaceflights although noise levels were lower than those normally associated with noise-induced hearing loss in ground-based operations. The present study was conducted to determine whether prolonged exposure (70 h) to levels (72 dBA) recorded on the International Space Station (ISS) service module would impact diverse measures of auditory function, as well as cognition and memory, motivation, and cardiovascular function. METHOD: Five mixed gender subgroups of five normal-hearing subjects, aged 20-50 yr, were sequestered for 70 h in an environment that modeled conditions on the ISS. They were assigned to one of three background conditions: quiet (n = 5), continuous noise from the ISS service module (n = 10), or continuous noise during the day only (n = 10). Subjects were tested repeatedly within and across days as individuals or pair mates. RESULTS: There were no negative effects of the noise on any of the outcome measures. Introduction of a delay or noise in a communication channel used in the assessment of speech communicability significantly affected the time taken for joint problem solving by partners. DISCUSSION: The results of this study were not consistent with the observation of hearing loss measured after spaceflights. Nor were changes evident in cognition, motivation, or cardiovascular function. Factors which might account for the discrepancy are discussed.

Adult↗
PubMed1979

Simulation of space cabin atmosphere.

The Soyuz 22 space cabin atmosphere was studied for volatile organic trace contaminants. By gas chromatography the following constituents were identified: methane, ethane, heptane, methanol, ethanol, n-propanol, acetaldehyde, acetone, ethyl benzene. Except for acetone, concentrations of the above compounds were close to the values determined in the mock-up experiments.

Air Conditioning↗
PubMed1989

Space vehicle approach velocity judgments under simulated visual space conditions.

There were 35 volunteers who responded when they first perceived an increase in apparent size of a collimated, two-dimensional perspective image of an Orbiter vehicle. The variables of interest included the presence (or absence) of a fixed reticle within the field of view (FOV), background starfield velocity, initial range to the vehicle and vehicle closure velocity. It was found that: 1) increasing vehicle approach velocity yielded a very small (but significant) effect of faster detection of vehicle movement, nevertheless, response variability was relatively large; 2) including the fixed reticle in the FOV produced significantly slower detection of vehicle radial movement, however this occurred only at the largest range and the magnitude of the effect was only about 15% of the one sigma value; and 3) increasing background star velocity during this judgment led to slower detection of vehicle movement. While statistically significant, this effect was small and occurred primarily at the largest range. A possible explanation for the last two findings is that other static and dynamic objects within the visual field may compete for available attention which otherwise would be available for judging image expansion; thus, the target's retinal image has to expand more than otherwise for its movement to be detected. This study also showed that the Proximity Operations Research Mockup at NASA/Ames can be used effectively to investigate a variety of visual judgment questions related to future space operations. These findings are discussed in relation to previous research and possible underlying mechanisms.

Adult↗
PubMed2004

Distributed interactive communication in simulated space-dwelling groups.

This report describes the development and preliminary application of an experimental test bed for modeling human behavior in the context of a computer generated environment to analyze the effects of variations in communication modalities, incentives and stressful conditions. In addition to detailing the methodological development of a simulated task environment that provides for electronic monitoring and recording of individual and group behavior, the initial substantive findings from an experimental analysis of distributed interactive communication in simulated space dwelling groups are described. Crews of three members each (male and female) participated in simulated "planetary missions" based upon a synthetic scenario task that required identification, collection, and analysis of geologic specimens with a range of grade values. The results of these preliminary studies showed clearly that cooperative and productive interactions were maintained between individually isolated and distributed individuals communicating and problem-solving effectively in a computer-generated "planetary" environment over extended time intervals without benefit of one another's physical presence. Studies on communication channel constraints confirmed the functional interchangeability between available modalities with the highest degree of interchangeability occurring between Audio and Text modes of communication. The effects of task-related incentives were determined by the conditions under which they were available with Positive Incentives effectively attenuating decrements in performance under stressful time pressure.

Adaptation, Psychological↗
PubMed1997

Psychological study of a crew in long-term space flight simulation.

This research derives from a 60-day isolation study realized for the European Space Agency (ESA) as a simulation of space flights. Three goals were pursued in this study: (a) to study individual and group responses to the stress factors specific to the simulation; (b) to make a critical comparison of a variety of tools and methods used for this purpose; and (c) to express recommendations for future research. Direct methods (questionnaires, tests) and indirect methods (observation) were used in an individual and a whole group assessment. The group did not show important stress manifestations during the isolation period. It maintained its cohesion by opposing the external authority. Some tools were more efficient than others: The qualitative and indirect methods have revealed much more information than the quantitative or direct methods that reinforced one's defense to avoid criticism.

Aerospace Medicine↗