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PubMedDate not supplied

Energy utilization rates during shuttle extravehicular activities.

The work rates or energy utilization rates during EVA are major factors in sizing of life support systems. These rates also provide a measure of ease of EVA and its cost in crew fatigue. From the first Shuttle EVA on the STS-6 mission in 1983, we have conducted 59 man-EVA and 341 man-hours of EVA. Energy utilization rates have been measured on each of these EVA. Metabolic rate was measured during each EVA using oxygen utilization corrected for suit leakage. From 1981-1987, these data were available for average data over the EVA or over large segments of the EVA. Since 1987, EVA oxygen utilization data were available at 2-minute intervals. The average metabolic rate on Shuttle EVA (194 kcal/hr.) has been significantly lower than metabolic rates during Apollo and Skylab missions. Peak rates have been below design levels, infrequent, and of short duration. The data suggest that the energy cost of tasks may be inversely related to the degree of training for the task. The data provide insight on the safety margins provided by life support designs and on the energy cost of Station construction EVA.

Aerospace Medicine↗
PubMed1994

Past, present, and future: the U.S. EVA program.

This paper provides an overview and summary of U.S. extravehicular activity accomplishments of the last 26 years, Space Shuttle missions having scheduled extravehicular activities to be performed over the next several years, extravehicular activities expected to be necessary to support Space Station Freedom assembly tasks and operations, and potential extravehicular activity roles of the NASA Space Exploration Initiative Program.

Astronauts↗
PubMed1995

EVA 2000: a European/Russian space suit concept.

For the European manned space activities an EVA space suit system was being developed in the frame of the Hermes Space Vehicle Programme of the European Space Agency (ESA). The space suit was to serve the needs for all relevant extravehicular activities for the Hermes Columbus operations planned to begin in 2004. For the present Russian manned space programme the relevant EVAs are performed by the Orlan-DMA semi-rigid space suit. The origin of its development reaches back to the 1970s and has since been adapted to cover the needs for extravehicular activities on Salyut and MIR until today. The latest modification of the space suit, which guaranteed its completely self-contained operation, was made in 1988. However, Russian specialists considered it necessary to start developing an EVA space suit of a new generation, which would have improved performance and would cover the needs by the turn of the century and into the beginning of the next century. Potentially these two suit developments could have a lot in common based on similarities in present concepts. As future manned space activities become more and more an international effort, a safe and reliable interoperability of the different space suit systems is required. Based on the results of the Munich Minister Conference in 1991, the European Space Agency and the Russian Space Agency agreed to initiate a requirements analysis and conceptual design study to determine the feasibility of a joint space suit development, EVA 2000. The design philosophy for the EVA 2000 study was oriented on a space suit system design of: space suit commonality and interoperability; increased crew productivity and safety; increase in useful life and reduced maintainability; reduced development and production cost. The EVA 2000 feasibility study was performed in 1992, and with the positive conclusions for EVA 2000, this approach became the new joint European Russian EVA Suit 2000 Development Programme. This paper gives an overview of the results of the feasibility study and presents the joint requirements and the proposed design concept of a jointly developed European Russian space suit.

Equipment Design↗
PubMed2003

The SOS-LUX-LAC-FLUORO-Toxicity-test on the International Space Station (ISS).

In the 21st century, an increasing number of astronauts will visit the International Space Station (ISS) for prolonged times. Therefore it is of utmost importance to provide necessary basic knowledge concerning risks to their health and their ability to work on the station and during extravehicular activities (EVA) in free space. It is the aim of one experiment of the German project TRIPLE-LUX (to be flown on the ISS) to provide an estimation of health risk resulting from exposure of the astronauts to the radiation in space inside the station as well as during extravehicular activities on one hand, and of exposure of astronauts to unavoidable or as yet unknown ISS-environmental genotoxic substances on the other. The project will (i) provide increased knowledge of the biological action of space radiation and enzymatic repair of DNA damage, (ii) uncover cellular mechanisms of synergistic interaction of microgravity and space radiation and (iii) examine the space craft milieu with highly specific biosensors. For these investigations, the bacterial biosensor SOS-LUX-LAC-FLUORO-Toxicity-test will be used, combining the SOS-LUX-Test invented at DLR Germany (Patent) with the commercially available LAC-FLUORO-Test. The SOS-LUX-Test comprises genetically modified bacteria transformed with the pBR322-derived plasmid pPLS-1. This plasmid carries the promoterless lux operon of Photobacterium leiognathi as a reporter element under control of the DNA-damage dependent SOS promoter of ColD as sensor element. This system reacts to radiation and other agents that induce DNA damages with a dose dependent measurable emission of bioluminescence of the transformed bacteria. The analogous LAC-FLUORO-Test has been developed for the detection of cellular responses to cytotoxins. It is based on the constitutive expression of green fluorescent protein (GFP) mediated by the bacterial protein expression vector pGFPuv (Clontech, Palo Alto, USA). In response to cytotoxic agents, this system reacts with a dose-dependent reduction of GFP-fluorescence. Currently, a fully automated miniaturized hardware system for the bacterial set up, which includes measurements of luminescence and fluorescence or absorption and the image analysis based evaluation is under development. During the first mission of the SOS-LUX-LAC-FLUORO-Toxicity-Test on the ISS, a standardized, DNA-damaging radiation source still to be determined will be used as a genotoxic inducer. A panel of recombinant Salmonella typhimurium strains carrying either the SOS-LUX plasmid or the fluorescence-mediating lac-GFPuv plasmid will be used to determine in parallel on one microplate the genotoxic and the cytotoxic action of the applied radiation in combination with microgravity. Either in addition to or in place of the fluorometric measurements of the cytotoxic agents, photometric measurements will simultaneously monitor cell growth, giving additional data on survival of the cells. The obtained data will be available on line during the TRIPLE-LUX mission time. Though it is the main goal during the TRIPLE-LUX mission to measure the radiation effect in microgravity, the SOS-LUX-LAC-FLUORO-Toxicity-test in principle is also applicable as a biomonitor for the detection and measurement of genotoxic substances in air or in the (recycled) water system on the ISS or on earth in general.

Cosmic Radiation↗
PubMedDate not supplied

[Physiologico-hygienic provisions for cosmonauts for their orbital flight].

This paper briefly describes physiologo-hygienic evaluations of space suits, data of the preflight training and extravehicular activities of the Salyut-6 crewmembers. It discusses changes in physiological parameters, energy expenditures, heat release and associated performance of the autonomic life support system. The paper also analyzes physiologo-hygienic aspects of the extravehicular activity of the Salyut-6 crewmembers.

Aerospace Medicine↗
PubMed1987

Man in space.

Today, more than 20 years after the first in the world man's space walk, soviet cosmonautics gained large experience of extravehicular activity (EVA). Space suits of high reliability, onboard facilities for passing through the airlock, sets of special tools and technological rigging, as well as procedures for carrying out various EVA's were developed. In the course of the Salyut-7 space station orbital operation the EVA's have become regular. The author of the report as the participant of the EVA's considers the main steps of man activities in space and analyzes specific problems arised in performing such activities.

Astronauts↗
PubMed2003

Prediction of muscle performance during dynamic repetitive movement.

BACKGROUND: During long-duration spaceflight, astronauts experience progressive muscle atrophy and often perform strenuous extravehicular activities. Post-flight, there is a lengthy recovery period with an increased risk for injury. Currently, there is a critical need for an enabling tool to optimize muscle performance and to minimize the risk of injury to astronauts while on-orbit and during post-flight recovery. Consequently, these studies were performed to develop a method to address this need. METHODS: Eight test subjects performed a repetitive dynamic exercise to failure at 65% of their upper torso weight using a Lordex spinal machine. Surface electromyography (SEMG) data was collected from the erector spinae back muscle. The SEMG data was evaluated using a 5th order autoregressive (AR) model and linear regression analysis. RESULTS: The best predictor found was an AR parameter, the mean average magnitude of AR poles, with r = 0.75 and p = 0.03. This parameter can predict performance to failure as early as the second repetition of the exercise. CONCLUSION: A method for predicting human muscle performance early during dynamic repetitive exercise was developed. The capability to predict performance to failure has many potential applications to the space program including evaluating countermeasure effectiveness on-orbit, optimizing post-flight recovery, and potential future real-time monitoring capability during extravehicular activity.

Adult↗
PubMed2005

Extravehicular mobility unit training and astronaut injuries.

BACKGROUND: Astronaut spacewalk training can result in a variety of symptom complaints and possible injuries. This study quantified and characterized signs, symptoms, and injuries resulting from extravehicular activity spacesuit training at NASA's Neutral Buoyancy Laboratory, Johnson Space Center, Houston, TX, immersion facility. METHODS: We identified the frequency and incidence of symptoms by location, mechanisms of injury, and effective countermeasures. Recommendations were made to improve injury prevention, astronaut training, test preparation, and training hardware. At the end of each test, a questionnaire was completed documenting signs and symptoms, mechanisms of injury, and countermeasures. RESULTS: Of the 770 tests, there were 190 in which suit symptoms were reported (24.6%). There were a total of 352 reported suit symptom comments. Of those symptoms, 166 were in the hands (47.16%), 73 were in the shoulders (20.7%), and 40 were in the feet (11.4%). Others ranged from 6.0% to 0.28%, respectively, from the legs, arms, neck, trunk, groin, and head. Causal mechanisms for the hands included moisture and hard glove contacts resulting in fingernail injuries; in the shoulders, hard contact with suit components and strain mechanisms; and in the feet, hard boot contact. The severity of symptoms was highest in the shoulders, hands, and feet. CONCLUSIONS: Most signs and symptoms were mild, self-limited, of brief duration, and were well controlled by available countermeasures. Some represented the potential for significant injury with consequences affecting astronaut health and performance. Correction of extravehicular activity training-related injuries requires a multidisciplinary approach to improve prevention, medical intervention, astronaut training, test planning, and suit engineering.

Arm Injuries↗
PubMed2004

Astronaut EVA exposure estimates from CAD model spacesuit geometry.

Ongoing assembly and maintenance activities at the International Space Station (ISS) require much more extravehicular activity (EVA) than did the earlier U.S. Space Shuttle missions. It is thus desirable to determine and analyze, and possibly foresee, as accurately as possible what radiation exposures crew members involved in EVAs will experience in order to minimize risks and to establish exposure limits that must not to be exceeded. A detailed CAD model of the U.S. Space Shuttle EVA Spacesuit, developed at NASA Langley Research Center (LaRC), is used to represent the directional shielding of an astronaut; it has detailed helmet and backpack structures, hard upper torso, and multilayer space suit fabric material. The NASA Computerized Anatomical Male and Female (CAM and CAF) models are used in conjunction with the space suit CAD model for dose evaluation within the human body. The particle environments are taken from the orbit-averaged NASA AP8 and AE8 models at solar cycle maxima and minima. The transport of energetic particles through space suit materials and body tissue is calculated by using the NASA LaRC HZETRN code for hadrons and a recently developed deterministic transport code, ELTRN, for electrons. The doses within the CAM and CAF models are determined from energy deposition at given target points along 968 directional rays convergent on the points and are evaluated for several points on the skin and within the body. Dosimetric quantities include contributions from primary protons, light ions, and electrons, as well as from secondary brehmsstrahlung and target fragments. Directional dose patterns are displayed as rays and on spherical surfaces by the use of a color relative intensity representation.

Astronauts↗
PubMed1994

U.S. prebreathe protocol.

This paper identifies and describes the prebreathe protocol currently used by the U.S. Space Shuttle Program to provide astronauts the capability to safely perform extravehicular activity. A comparison of planned vs actual prebreathe experience through the STS-37 Mission is also provided.

Aerospace Medicine↗
PubMed1994

EVA safety design guidelines.

An Extravehicular Mobility Unit is a closed and isolated environment that protects the astronaut from exposure to space environment. Eighty-four percent of the possible hardware failures occurring during Extravehicular Activity (EVA) would result in an abort of the EVA. Fifty-two percent of these failure modes would result in a loss of a critical life support function and directly compromise crew safety. Crew safety is not, however, limited to controlling hardware failures. Safety can be compromised by improper in-flight servicing or induced by interfacing equipment during EVA related activity. This paper addresses these potential hazard sources and approaches used to enhance equipment reliability and astronaut safety.

Air Conditioning↗
PubMed2000

Effects of heterogeneous structure and diffusion permeability of body tissues on decompression gas bubble dynamics.

To gain insight into the special nature of gas bubbles that may form in astronauts, aviators and divers, we developed a mathematical model which describes the following: 1) the dynamics of extravascular bubbles formed in intercellular cavities of a hypothetical tissue undergoing decompression; and 2) the dynamics of nitrogen tension in a thin layer of intercellular fluid and in a thick layer of cells surrounding the bubbles. This model is based on the assumption that, due to limited cellular membrane permeability for gas, a value of effective nitrogen diffusivity in the massive layer of cells in the radial direction is essentially lower compared to conventionally accepted values of nitrogen diffusivity in water and body tissues. Due to rather high nitrogen diffusivity in intercellular fluid, a bubble formed just at completion of fast one-stage reduction of ambient pressure almost instantly grows to the size determined by the initial volume of the intercellular cavity, surface tension of the fluid, the initial nitrogen tension in the tissue, and the level of final pressure. The rate of further bubble growth and maximum bubble size depend on comparatively low effective nitrogen diffusivity in the cell layer, the tissue perfusion rate, the initial nitrogen tension in the tissue, and the final ambient pressure. The tissue deformation pressure performs its conservative action on bubble dynamics only in a limited volume of tissue (at a high density of formed bubbles). Our model is completely consistent with the available data concerning the random latency times to the onset of decompression sickness (DCS) symptoms associated with hypobaric decompressions simulating extravehicular activity. We believe that this model could be used as a theoretical basis for development of more adequate methods for the DCS risk prediction.

Atmospheric Pressure↗
PubMed1988

Review of basic medical results of the Salyut-7--Soyuz-T 8-month manned flight.

This paper presents the results of medical investigations performed in the Salyut-7 8-month mission in which a professional physician took part. The paper contains anthropometric measurements, results of investigating the vestibular function, cardiovascular function at rest and in response to multi-step tests (with emphasis on echocardiographic measurements), metabolic parameters and hormonal status. It also discusses medical aspects of the extravehicular activity. The medical investigations, although some new methods were applied, provided the continuity of methodical approaches and data accumulated in previous missions.

Adaptation, Physiological↗
PubMed1995

EVA Suit 2000: a joint European/Russian space suit design.

A feasibility study in 1992 showed the benefits of a common European Russian space suit development, EVA Suit 2000, replacing the Russian space suit Orlan-DMA and the planned European Hermes EVA space suit at the turn of the century. This EVA Suit 2000 is a joint development initiated by the European Space Agency (ESA) and the Russian Space Agency (RKA). The main objectives of this development program are: first utilization aboard the Russian Space Station MIR-2; performance improvement with respect to current operational suits; development cost reduction. Russian experience gained with the present extravehicular activity (EVA) suit on the MIR Space Station and extensive application of European Technologies will be needed to achieve these ambitious goals. This paper presents the current status of the development activities, the space suit system design and concentrates in more detail on life support aspects. Specific subjects addressed will include the overall life support conceptual architecture, design features, crew comfort and operational considerations.

Computer Systems↗
PubMed1994

EVA design: lessons learned.

Extravehicular Activities (EVAs) are very demanding and specialized space flight activities. There are many aspects to consider in the design of hardware, tools, and procedures to be used on an EVA mission. To help minimize costs and optimize the EVA productivity, experience shows that astronauts should become involved early in the design process.

Astronauts↗
PubMed1998

[Decompression sickness-one of the vital problems of aerospace medicine].

The author reviews the literature on decompression sickness (DCS) constituting one of the major problems of aerospace medicine. He speculates on the terms describing this health condition and offers the retrospective of hypothesised causes for DCS development. The paper outlines main DCS symptoms and reports statistics on the DCS incidence rate in flying personnel when piloting aircraft and training in altitude chambers, and in volunteered test-subjects during physiological experiments with simulated ascents in order to mimic the extravehicular activities of cosmonauts and to test the altitude gear. Underlined is the value of publications by many Russian and foreign investigators who contributed significantly to development of the scientific and applied aspects of this problem. The currently available and theoretically possible countermeasures against DCS in cosmonauts during EVA are considered.

Aerospace Medicine↗
PubMed2000

Life in extreme environments: how will humans perform on Mars?

This review of astronaut extravehicular activity (EVA) and the details of American and Soviet/Russian spacesuit design focuses on design recommendations to enhance astronaut safety and effectiveness. Innovative spacesuit design is essential, given the challenges of future exploration-class missions in which astronauts will be called upon to perform increasingly complex and physically demanding tasks in the extreme environments of microgravity and partial gravity.

Extravehicular Activity↗