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PubMed2005

SPACE: a suite of tools for protein structure prediction and analysis based on complementarity and environment.

We describe a suite of SPACE tools for analysis and prediction of structures of biomolecules and their complexes. LPC/CSU software provides a common definition of inter-atomic contacts and complementarity of contacting surfaces to analyze protein structure and complexes. In the current version of LPC/CSU, analyses of water molecules and nucleic acids have been added, together with improved and expanded visualization options using Chime or Java based Jmol. The SPACE suite includes servers and programs for: structural analysis of point mutations (MutaProt); side chain modeling based on surface complementarity (SCCOMP); building a crystal environment and analysis of crystal contacts (CryCo); construction and analysis of protein contact maps (CMA) and molecular docking software (LIGIN). The SPACE suite is accessed at http://ligin.weizmann.ac.il/space.

Amino Acids↗
PubMed1982

Space shuttle suit alert system visual acuity problem.

The National Aeronautics and Space Administration (NASA) requested solution of a visual acuity problem that presbyopic astronauts had when viewing an alert system visual display attached to their Space Shuttle suits. Solutions wee analyzed in the context of constraints which prohibited major modifications of the suits. The solution to the problem was to mount Fresnel lens strips on the helmet so that presbyopic astronauts could view the visual display clearly.

Adult↗
PubMed2000

Thermal physiological consideration of precooling procedures in manned space craft.

OBJECTIVE: To explore a space craft precooling temperature at which excessive thermal stress on the crew member could be prevented or reduced in an overheated launch or reentry module. METHOD: Five young male volunteers wearing a space suit participated in 25 tests at sea level. The space suit was either ventilated in a volume air flow rate of 100 L/min (STPD) with ambient air at temperatures (Ta) of 15 degrees C, 10 degrees C, and 5 degrees C, respectively, or not ventilated. Rectal (Tr), mean skin (Tsk) and mean body (Tb) temperatures were measured. RESULT: At Ta 15 degrees C, Tr decreased without significance (from 37.0 +/- 0.2C to 36.7 +/- 0.3 degrees C) in 120-min tests, whereas mean Tsk and mean Tb decreased significantly, and subjects had local cold strain whether the space suit was ventilated or not; while at Ta 10 degrees C, Tr decreased from 37.0 +/- 0.3 degrees C to 36.3 +/- 0.3 degrees C (P < 0.05), subjects had a whole body cold strain, and both mean Tsk and Tb dropped continuously and significantly. CONCLUSION: Ambient temperature 15 degrees C, at which the thermal comfort states of crew was not significantly degraded, was acceptable after precooling in a space craft.

Adolescent↗
PubMed1994

Suited crewmember productivity.

Analysis of the extravehicular activity (EVA) sortie experience gained in the former Soviet Union and physiologic hygienic aspect of space suit design and development shows that crewmember productivity is related to the following main factors: -space suit microclimate (gas composition, pressure and temperature); -limitation of motion activity and perception, imposed by the space suit; -good crewmember training in the ground training program; -level of crewmember general physical performance capabilities in connection with mission duration and intervals between sorties; -individual EVA experience (with accumulation) at which workmanship improves, while metabolism, physical and emotional stress decreases; -concrete EVA duration and work rate; -EVA bioengineering, including selection of tools, work station, EVA technology and mechanization.

Astronauts↗
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↗
PubMedDate not supplied

[The ultrasonic location of gas bubbles in the human bloodstream during work in a spacesuit].

The results of testing a procedure of ultrasonic location of the gas bubbles (GB) in man during space suit operations to simulate an extravehicular activity (EVA) are presented. Doppler echotachocardiograph "Rhythm" operating at ultrasonic frequency of 1.76 mHz was used as a GB detector. The device "Rhythm" integrated with a special flat transducer of 23 mm in diameter and 4 mm in width was positioned on the subject chest above the pulmonary artery projection. During 4-6 hour human operations while wearing pressurized (276-290 mm Hg) space suit, in 7 of 12 tests performed a stable and qualitative signal of the arterial blood flow in the lungs was recorded. In case of an unstable signal, in order that its quality be improved the posture of test subject was changed and the signal was recorded during a short-term expired breath-holding. Cardiac GB formation was noted during 6 tests in 2 subjects. The first GBs appeared at the 30th, 33rd, 70th, 111th, 114th and 180th minute after producing an operating reduced pressure in space suit. The time of GB detection on the average was 89.7 min. The maximum intensity of GB signal was 3-4 scores on Spencer's scale, but altitude decompression sickness symptoms did not develop in the test subjects. The risk of developing the altitude decompression sickness as opposed to the results of control experiments without use of space suit is discussed.

Adult↗
PubMed1998

[The influence of space loading suits on interhemispheric asymmetry of the brain in infantile spastic cerebral palsy].

The paper presents the study concerning influence of somatosensory stimulation (single wearing of either space loading costume "PENGUIN" or its modification--"ADELY" costume) on the individual profile of interhemispheral cerebral assymmetry (IPIHCA) in patients with spastic form of infantile cerebral paralysis (ICP). The computer stabilograph analyzed motor arms' asymmetry, sensory asymmetry of visual hemiareas, asymmetry of the position of centre of gravity. It is shown that peculiarities of the realization of the standing position either with visual control or without it both in healthy individuals and in patients depended on initial IPIHCA. Initial stability was higher in healthy individuals than in patients, besides in healthy persons it was higher in right-handers while in patients--in left-handers. There was possibility of changes of both IPIHCA and stability during keeping up vertical position even during single somatosensory stimulation. For elaboration of new criteria of the estimation of the efficiency of treatment in patients with CNS damages, including ICP, it is necessary to take into consideration different influence of somatosensory stimulation on IPIHC in right-handers and left-handers.

Adolescent↗
PubMed1997

Identification and status of design improvements to the NASA Shuttle EMU for International Space Station application.

To meet the significant increase in EVA demand to support assembly and operations of the International Space Station (ISS), NASA and industry have improved the current Shuttle Extravehicular Mobility Unit (EMU), or "space suit", configuration to meet the unique and specific requirements of an orbital-based system. The current Shuttle EMU was designed to be maintained and serviced on the ground between frequent Shuttle flights. ISS will require the EMUs to meet increased EVAs out of the Shuttle Orbiter and to remain on orbit for up to 180 days without need for regular return to Earth for scheduled maintenance or refurbishment. Ongoing Shuttle EMU improvements have increased reliability, operational life and performance while minimizing ground and on-orbit maintenance cost and expendable inventory. Modifications to both the anthropomorphic mobility elements of the Space Suit Assembly (SSA) as well as to the Primary Life Support System (PLSS) are identified and discussed. This paper also addresses the status of on-going Shuttle EMU improvements and summarizes the approach for increasing interoperability of the U.S. and Russian space suits to be utilized aboard the ISS.

Environment, Controlled↗
PubMed1998

[Analysis of decompression safety during extravehicular activity of astronauts in the light of probability theory].

Objectives of the study were comparative assessment of the risk of decompression sickness (DCS) in human subjects during shirt-sleeve simulation of extravehicular activity (EVA) following Russian and U.S. protocols, and analysis of causes of the difference between real and simulated EVA decompression safety. To this end, DCS risk during exposure to a sing-step decompression was estimated with an original method. According to the method, DCS incidence is determined by distribution of nucleation efficacy index (z) in the worst body tissues and its critical values (zm) as a function of initial nitrogen tension in these tissues and final ambient pressure post decompression. Gaussian distribution of z values was calculated basing on results of the DCS risk evaluation on the U.S. EVA protocol in an unsuited chamber test with various pre-breath procedures (Conkin et al., 1987). Half-time of nitrogen washout from the worst tissues was presumed to be 480 min. Calculated DCS risk during short-sleeve EVA simulation by the Russian and U.S. protocols with identical physical loading made up 19.2% and 23.4%, respectively. Effects of the working spacesuit pressure, spacesuit rigidity, metabolic rates during operations in EVA space suit, transcutaneous nitrogen exchange in the oxygen atmosphere of space suit, microgravity, analgesics, short compression due to spacesuit leak tests on the eye of EVA are discussed. Data of the study illustrate and advocate for high decompression safety of current Russian and U.S. EVA protocols.

Astronauts↗
PubMed1995

The feasibility of Doppler monitoring during EVA.

During extravehicular activities (EVA) outside the spacecraft, astronauts have to work under reduced pressure in a space suit. This pressure reduction induces the risk of decompression sickness (DCS) by the formation of gas bubbles from excess nitrogen dissolved in the organism by breathing air at normal pressure. Under laboratory conditions the gas bubbles moving in the blood stream can be detected by the non-invasive ultrasonic Doppler method. By early detection of excessive bubble formation the development of DCS symptoms may be prevented by early application of preventative measures. The method could also be useful when applied in the space suit in order to compare the results of laboratory tests with operational results, because there is a discrepancy according to the DCS risk of laboratory experiments and actual EVA missions, where no symptoms have been reported yet. A prototype Doppler sensor has been developed and implemented in the Russian Orlan suit. To investigate the feasibility of this method under simulated space conditions, the equipment has been used in a series of 12 thermovacuum chamber tests with suited subjects, where intravenous bubble formation was compared to unsuited control experiments. In more than 50% of the suited tests good Doppler recordings could be achieved. In some cases with unsatisfying results the signal could be improved by breathholding. Although the results do not yet allow any conclusion about a possible difference between suited and unsuited subjects due to the small number of tests performed, the method proved its feasibility for use in EVA suits and should be further developed to enhance the safety of EVA procedures.

Aerospace Medicine↗
PubMed2004

[A simulation facility for low temperature water surface environment].

OBJECTIVE: To simulate the water environment during floating status after astronauts returned and splashed down on the sea because of space capsule emergency in the launching stage. METHOD: Environmental temperature in the laboratory and water-temperature in the tank were auto-controlled individually according to heat charge calculation. To meet the need of maintaining the uniformity of water-temperature, the structure of the water circulation pipeline was specially designed to increase thread-conflux and laminar flow effect. RESULT: It was proved that the experimental system satisfied the requirements for medical research and evaluation by its high precision and uniformity which even exceeded the design requirements. After acceptance, its performance was further proved in the field experiment of "the medical evaluation of the soak and cold resisting garment." CONCLUSION: The equipment provides satisfactory experimental condition for medical evaluation of the space suit used in the "Shenzhou" space capsule and simulated the low-temperature water environment for studies of human reaction in the floating status and medical evaluation of relative products in the area of aerospace.

Aerospace Medicine↗
PubMed2003

Mechanical counter pressure on the arm counteracts adverse effects of hypobaric exposures.

INTRODUCTION: Current space suits have limited movement due to gas pressurization during exposure to the vacuum of space. Alternatively, if pressure is applied by an elastic garment vs. pneumatic garment to produce mechanical counter pressure (MCP), several advantages are possible. In this study, we investigate local microcirculatory and other effects produced with and without a prototype MCP glove and sleeve during exposure to varying levels of vacuum. METHODS: The entire arms of eight male volunteers were studied at normal ambient pressure and during 5 min exposures to -50, -100, and -150 mm Hg with and without the MCP glove and sleeve. Pressure distribution, skin microvascular flow, and temperature were measured. RESULTS: The MCP glove and sleeve generated over 200 mm Hg on the middle finger, dorsum of the hand, and the wrist. However, pressure was significantly lower on the forearm and the upper arm. Without the glove and sleeve, only two of eight subjects tolerated -100 mm Hg. Also, no subject tolerated -150 mm Hg. However, subjects tolerated all vacuum pressures wearing the glove and sleeve. Skin microvascular flow and temperature remained within control values with the glove and sleeve at a chamber pressure of -150 mm Hg. DISCUSSION: The MCP glove and sleeve counteracts adverse effects of vacuum exposures due to lower pressure differentials. Pressure levels over the hand and wrist are similar to those of the current U.S. space suit glove and sleeve, but additional development is required to increase MCP over the forearm and upper arm.

Adult↗
PubMed1973

Biomechanics of locomotion in subgravity.

The speed of walking or running on the moon as compared with earth is appreciably reduced, in spite of mechanisms of compensation taking place such a forward leaning of the body and an increase of the horizontal component of the push of the foot on the ground. However on the moon the same speed of locomotion as on earth can be reached by shifting to a different mechanism of locomotion, i. e. progression by jumps, which becomes possible on the moon because of the reduction of the body weight. The energy cost of locomotion is certainly less on the moon than on earth, about 1/6. Were the subject not restrained by the space suit, progression by jumps at 20 km hr-1 on the moon would cost no more than 10 ml kg-1 min-1 of oxygen, the same as walking on earth at 6 km hr-1. Maximal acceleration of the body as in sprinting, or deceleration as in stopping, attains much higher values on earth than on the moon. While sprinting on earth may involve the maximal muscular power, sprinting or progressing at the highest speed on the moon involves only a fraction of the maximal power, mainly because of the reduced maximal frequency of the steps (or jumps). The maximal height of the jump on both feet on the moon could attain 4 m in the unrestricted subject. An analysis is wanted on the restriction of the movements brought about by the space suit and on the energy cost of progression.

Biomechanical Phenomena↗
PubMed1973

Some psychological and engineering aspects of the extravehicular activity of astronauts.

One of the main in-flight problems being fulfilled by astronauts is the preparation for and realization of egress into open space for the purpose of different kinds of extravehicular activity, such as, the performance of scientific experiments, repairing and dismantling operations etc. The astronaut's activity outside the space vehicle is the most difficult item of the space flight programme, which is complicated by a number of space factors affecting a man, viz. dynamic weightlessness, work in a space suit under conditions of excessive pressure, difficulties of space orientation etc. The peculiarities mentioned require special training of the cosmonaut. The physical training involves a series of exercises forming the body-control habits necessary for work in a state of weightlessness. In a new kind of training use is made of equipment simulating the state of weightlessness. From analysis of the available data and the results of my own investigations during ground training and the Soyuz 4 and 5 flights one can establish the following peculiarities of the astronaut's extravehicular activity: (1) Operator response lag in the planned algorithm; (ii) systematic appearance of some stereotype errors in the mounting and dismantling of the outer equipment and in scientific-technical experiments; (iii) a high degree of emotional strain and 30-35% decrease in in-flight working capacity of the astronaut compared with the ground training data; (iv) a positive influence of space adaptation on the cosmonaut and the efficiency of his work in open space; (v) the necessity for further engineering and psychological analysis of the astronaut's activity under conditions of the long space flight of the multi-purpose orbital station. One of the main reasons for the above peculiarities is the violation of the control-coordination functions of the astronaut in the course of the dynamical operations. The paper analyses the extravehicular activity of the astronaut and presents some recommendations for its more efficient realization. Proposals are given concerning the complex engineering, psychological and technical investigations to be made during in-flight egress.

Aerospace Medicine↗