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At least 145 records · Page 8Linked to original sources
PubMed1998

A loglogistic model for altitude decompression sickness.

BACKGROUND: Altitude decompression sickness (DCS) is a potential hazard encountered during high altitude flights or during extravehicular activity in space. In this study, the loglogistic distribution was used to model DCS risk and symptom onset time. METHODS: The Air Force Research Laboratory, Brooks AFB, TX, has conducted studies on human subjects exposed to simulated altitudes in hypobaric chambers. The dataset from those studies was used to develop the DCS models and consisted of 975 subject-exposures to various altitudes, preoxygenation times, and exercise regimens. Since the risk of DCS is known to increase over time at altitude, and then decrease because of denitrogenation, the loglogistic model was fit to the data. The model assumes that the probability of DCS depends on several risk factors. Maximum likelihood estimates of the parameters were obtained using the statistical software package SAS. Cross validation techniques were provided to examine the goodness of fit of the model. RESULTS: The fitted model indicated that altitude, ratio of preoxygenation to exposure time, and exercise were the most significant risk factors. The model was used to predict the risk of DCS for a variety of exposure profiles. The predicted probability of DCS agreed very closely with the actual percentages in the database. CONCLUSION: The loglogistic distribution was found to be appropriate for modeling the risk of DCS. Based on the cross validation and validation results, we conclude that this model provides good estimates of the probability of DCS over time.

Adolescent↗
PubMed2002

[A dynamic model of the extravehicular (correction of extravehicuar) activity space suit].

Objective. To establish a dynamic model of the space suit base on the particular configuration of the space suit. Method. The mass of the space suit components, moment of inertia, mobility of the joints of space suit, as well as the suit-generated torques, were considered in this model. The expressions to calculate the moment of inertia were developed by simplifying the geometry of the space suit. A modified Preisach model was used to mathematically describe the hysteretic torque characteristics of joints in a pressurized space suit, and it was implemented numerically basing on the observed suit parameters. Result. A dynamic model considering mass, moment of inertia and suit-generated torques was established. Conclusion. This dynamic model provides some elements for the dynamic simulation of the astronaut extravehicular activity.

Extravehicular Activity↗
PubMed2005

[An experimental study of effects of active-heating-system for extravehicular spacesuit gloves on working performance].

OBJECTIVE: To observe the effects of active heating system for spacesuit gloves on extravehicular working performance. METHOD: After analyzing the factors with gloves influence on the working performance, the effects of active heating system for gloves were studied experimentally with aspects to fatigue, hand strength, dexterity and tactile sensing. RESULT: 1) Heating-system had not influence to grip; 2) Heating-system had 17% influence to fatigue except specific person; 3) Nut assembly and nipping pin showed that heating-system had little influence to dexterity; 4) Apperceiving shape of object and two-point distance showed heating-system had little influence to tactility. CONCLUSION: The active heating method is rational and has little influence on working performance.

Biomechanical Phenomena↗
PubMed1995

EVA-related activities in Japan.

Recognizing the importance and fertility of the extra vehicular activity technologies in future space development and utilization, some related research activities have been conducted in Japan, though it has not committed itself to developing its own manned space flight capability. The purpose of this paper is to introduce and evaluate these EVA-related activities and to indicate the next step for Japan to get into the era of manned space activities including EVA in reality.

Carbon Dioxide↗
PubMed1989

PPS-87: a new event oriented solar proton prediction model.

A new event-oriented solar proton prediction model has been developed and implemented at the USAF Space Environment forecast facility. This new model generates predicted solar proton time-intensity profiles for a number of user adjustable energy ranges and is also capable of making predictions for the heavy ion flux. The computer program is designed so a forecaster can select inputs based on the data available in near real-time at the forecast center as the solar flare is occurring. The predicted event amplitude is based on the electromagnetic emission parameters of the solar flare (either microwave or soft X-ray emission) and the solar flare position on the sun. The model also has an update capability where the forecaster can normalize the prediction to actual spacecraft observations of spectral slope and particle flux as the event is occurring in order to more accurately predict the future time-intensity profile of the solar particle flux. Besides containing improvements in the accuracy of the predicted energetic particle event onset time and magnitude, the new model converts the predicted solar particle flux into an expected radiation dose that might be experienced by an astronaut during EVA activities or inside the space shuttle.

Computer Simulation↗
PubMed2000

[A heat transfer model for liquid cooling garment (LCG) and its analysis].

Objective. To establish the heat transfer model for liquid cooling garment (LCG) and, basing on this model, to find the relations between the design parameters and heat removing, as well as that between the design parameters and heat transfer efficiency. Method. Heat transfer process of the LCG was analyzed according to engineering facts. Result. The relations between the design parameters and heat removing, and also that between the design parameters and heat transfer efficiency were interelative and the optimal values of the parameters were essential to the design of LCG. Conclusion. The results might be useful in the design of LCG in extra vehicular activity (EVA) space suit.

Body Temperature Regulation↗
PubMed1990

[Intertechnique's multifunction pressure regulator for spacesuits].

A dual mode pressure regulator has been successfully completed by Intertechnique. This regulator provides the regulated oxygen pressure required for the extra vehicular activity suit for Hermes. This regulator also enables high purge flow during suit donning. New technologies have been successfully developed by Intertechnique in order to provide a very high level of safety.

Equipment Design↗
PubMed2001

Some influences of the physical environment on human cognition.

The value of human work, even when it is primarily physical, arises from unique cognitive capabilities. This paper samples a broadly distributed research base regarding influences of the physical environment on human cognition. The presentation draws primarily on studies conducted within the context of dynamic physical domains of work, to address controls and information sources for enabling human intervention, and related reasoning and planning. Several examples illustrate the role of the environment as a source of information and as an influence on the sequencing of work activity. Life support is discussed both as an instance of a dynamic physical system, and for its potential to preclude direct engagement with the environment, with predictable cognitive consequences.

Astronauts↗
PubMed1992

Global approach to simulation: a gateway to long-term human presence in space.

The establishment of an autonomous European manned space capability is an objective set up by the ESA Council Meeting at the ministerial level, in 1985/1987. ESA's Long-Term Programme Office (LTPO), charged of the preparation of the programme for a European Manned Space Infrastructure (EMSI), started during 1988 to build up an intellectual framework in the domain of long-duration manned space missions. EMSI scope was eventually extended to embrace Moon/Mars missions and bases. Several exploratory studies on problems related to human factors in long-duration space missions were initiated by LTPO. The work of an ad-hoc group of experts (SIMIS Group) has been focused during 1989/1990 on the planning for simulation of such missions with a broad mandate, covering the physiological, psychological and operational aspects of long-duration exposure to microgravity and isolation/confinement. Preliminary results of SIMIS activities are reported. The HYDREMSI experiment, carried out in a terrestrial, analogous environment for 72 days during 1989, is described as an example of the envisaged simulations.

Astronauts↗
PubMedDate not supplied

Solar particle events and the International Space Station.

The high inclination orbit for the International Space Station poses a risk to astronauts on EVA during occasional periods of enhanced high energy particle flux from the sun known as Solar Particle Events. We are currently unable to predict these events within the few-hour lead time required for evasive action. Compounding the threat is the fact that station construction occurs during increasing solar activity and through the peak of the solar cycle. In this paper we present an overview of the risk, the current methods to provide forecasts of SPEs, and potential risk mitigation options.

Aerospace Medicine↗
PubMed2001

Some influences of the physical environment on human cognition.

The value of human work, even when it is primarily physical, arises from unique cognitive capabilities. This article samples a broadly distributed research base regarding influences of the physical environment on human cognition. The presentation draws primarily on studies conducted within the context of dynamic physical domains of work, to address controls and information sources for enabling human intervention, and related reasoning and planning. Several examples illustrate the role of the environment as a source of information and as an influence on the sequencing of work activity. Life support is discussed both as an instance of a dynamic physical system and for its potential to preclude direct engagement with the environment, with predictable cognitive consequences.

Aerospace Medicine↗
PubMed1991

EVA medical problems.

The experience gained in the USSR allows the following conclusions: physiological responses to EVA do not depend on flight duration in qualitative and quantitative terms. Physiological responses to EVA are mainly determined by following 3 factors: physiological activities; space suit environmental parameters; physiological stress. This paper reviews problems, associated with altitude decompression sickness; thermal regulation of the body, visual function and physiological psychological stress as well as individual EVA experience in physiological responses.

Aerospace Medicine↗
PubMedDate not supplied

Research progress and accomplishments on International Space Station.

The first research payloads reached the International Space Station (ISS) more than two years ago, with research operating continuously since March 2001. Seven research racks are currently on-orbit, with three more arriving soon to expand science capabilities. Through the first five expeditions, 60 unique NASA-managed investigations from 11 nations have been supported, many continuing into later missions. More than 90,000 experiment hours have been completed, and more than 1,000 hours of crew time have been dedicated to research, numbers that grow daily. The multidisciplinary program includes research in life sciences, physical sciences, biotechnology, Earth sciences, technology demonstrations as well as commercial endeavors and educational activities. The Payload Operations and Integration Center monitors the onboard activities around the clock, working with numerous Principal Investigators and Payload Developers at their remote sites. Future years will see expansion of the station with research modules provided by the European Space Agency and Japan, which will be outfitted with additional research racks.

Biological Science Disciplines↗
PubMed2003

Biological dosimetry in Russian and Italian astronauts.

Large uncertainties are associated with estimates of equivalent dose and cancer risk for crews of long-term space missions. Biological dosimetry in astronauts is emerging as a useful technique to compare predictions based on quality factors and risk coefficients with actual measurements of biological damage in-flight. In the present study, chromosomal aberrations were analyzed in one Italian and eight Russian cosmonauts following missions of different duration on the MIR and the international space station (ISS). We used the technique of fluorescence in situ hybridization (FISH) to visualize translocations in chromosomes 1 and 2. In some cases, an increase in chromosome damage was observed after flight, but no correlation could be found between chromosome damage and flight history, in terms of number of flights at the time of sampling, duration in space and extra-vehicular activity. Blood samples from one of the cosmonauts were exposed in vitro to 6 MeV X-rays both before and after the flight. An enhancement in radiosensitivity induced by the spaceflight was observed.

Astronauts↗
PubMed2000

In-situ resource utilization technologies for Mars life support systems.

The atmosphere of Mars has many of the ingredients that can be used to support human exploration missions. It can be "mined" and processed to produce oxygen, buffer gas, and water, resulting in significant savings on mission costs. The use of local materials, called ISRU (for in-situ resource utilization), is clearly an essential strategy for a long-term human presence on Mars from the standpoints of self-sufficiency, safety, and cost. Currently a substantial effort is underway by NASA to develop technologies and designs of chemical plants to make propellants from the Martian atmosphere. Consumables for life support, such as oxygen and water, will probably benefit greatly from this ISRU technology development for propellant production. However, the buffer gas needed to dilute oxygen for breathing is not a product of a propellant production plant. The buffer gas needs on each human Mars mission will probably be in the order of metric tons, primarily due to losses during airlock activity. Buffer gas can be separated, compressed, and purified from the Mars atmosphere. This paper discusses the buffer gas needs for a human mission to Mars and consider architectures for the generation of buffer gas including an option that integrates it to the propellant production plant.

Argon↗
PubMed1994

Rapid assessment of radiobiological doses for terrestrial and interplanetary space missions.

This paper presents the doses levels expected in orbits in chart form, covering the range 300-800 km of altitude and 0-90 degrees of inclination behind shieldings similar to the Hermes spacecraft and the EVA spacesuit matter distributions. These charts allow users to rapidly find the radiobiological dose received in the most critical organs of the human body either in normal situations or during a large solar event. Outside the magnetosphere, during interplanetary or lunar missions, when the dose received during crossing of the radiation belts become negligible, the dose is due to galactic cosmic rays (GCR) and solar flares. The correct radiobiological assessment of the components of this radiation field becomes a major problem. On the Moon a permanent ground-based station can be shielded by lunar materials against meteoroids and radiations. The radiobiological hazard, essentially linked to the solar flare risk during the transfer phase and the extra-station activities, may be solved by mission planning. For interplanetary flights the problem comes from both increased risk of solar events and from the continuous exposure to GCR. These energetic particles cannot be easily stopped by shieldings; cost considerations imply that more effective materials must be used. Impact on the vehicle design and the mission planning is important.

Atlantic Ocean↗
PubMed1992

Development of life support requirements for long-term space flight.

When humans move out into the solar system to stay for long durations, the most immediate challenge will be the provision of a life-supporting environment in locations that are naturally devoid of food, air, and water. Life support systems must provide these commodities in all phases of space flight--during intravehicular activity (IVA) and during extra-vehicle activity (EVA). Systems that support human life must provide: overall reliability in the space environment, allowing maintenance and component replacement in space; reduced resupply mass of consumables and spares; for planetary surfaces, the ability to utilize local resources for increased self sufficiency; and the minimized mass power and volume requirements necessary for all space flight systems. This paper will discuss the melding of these technical requirements in such a way as to meet the human needs of space flight.

Ecological Systems, Closed↗
PubMedDate not supplied

Canada and the International Space Station program: overview and status.

The twelve months since IAF 2000 have been perhaps the most exciting, challenging and rewarding months for Canada since the beginning of our participation in the International Space Station program in 1984. The highlight was the successful launch, on-orbit check out, and the first operational use of Canadarm2, the Space Station Remote Manipulator System, between April and July 2001. The anomalies encountered and the solutions found to achieve this success are described in the paper. The paper describes, also, the substantial progress that has been made, during the twelve months since IAF 2000, by Canada as it continues to complete work on all flight-elements of its contribution to the International Space Station and as we transition into real-time Space Station operations support and Canadian utilization. Canada's contribution to the International Space Station is the Mobile Servicing System (MSS), the external robotic system that is key to the successful assembly of the Space Station, the maintenance of its external systems, astronaut EVA support, and the servicing of external science payloads. The MSS ground segment that supports MSS operations, training, sustaining engineering, and logistics activities is reaching maturity. The MSS Engineering Support Center and the MSS Sustaining Engineering Facility are providing real-time support for on-orbit operations, and a Canadian Payloads Telescience Operations Center is now in place. Mission Controllers, astronauts and cosmonauts from all Space Station Partners continue to receive training at the Canadian Space Agency. The Remote Multi Purpose Room, one element of the MSS Operations Complex, will be ready to assume backroom support in 2002. Canada has completed work on identifying its Space Station utilization activities for the period 2000 through 2004. Also during the past twelve months the CSA drafted and is proceeding with the approval of a Canadian Space Station Commercialization Policy. Canadian astronauts have now participated in three ISS assembly missions--Julie Payette on STS-96, Marc Garneau on STS-97, and Chris Hadfield on STS-100 in April 2001 during which he performed Canada's first EVA and the successful installation of the Space Station Remote Manipulator System.

Astronauts↗