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At least 685 records · Page 38Linked to original sources
PubMed1995

Decision analysis as a life support technology assessment capability.

Applied research and technology development is often characterized by uncertainty, risk, and significant delays before tangible returns are obtained. Decision making regarding which technologies to advance and what resources to devote to them is a challenging but essential task, especially in a resource-constrained environment. In the application of life support technology to future manned space flight, new technology concepts typically are characterized by rough approximations of technology performance, uncertain future flight program needs, and a complex, time-intensive process to develop technology to a flight-ready status. Decision analysis is a quantitative, logic-based discipline that imposes formalism and structure to complex problems confronting a decision maker. It also accounts for the limits of knowledge available at the time a decision is needed. The utility of decision analysis to life support technology R&D was evaluated by applying it to two case studies. The methodology was found to provide useful insight for making technology development resource allocation decisions.

Costs and Cost Analysis↗
PubMed2005

Countermeasure for space flight effects on immune system: nutritional nucleotides.

Microgravity and its environment have adverse effects on the immune system. Abnormal immune responses observed in microgravity may pose serious consequences, especially for the recent directions of NASA for long-term space missions to Moon, Mars and deep Space exploration. The study of space flight immunology is limited due to relative inaccessibility, difficulty of performing experiments in space, and inadequate provisions in this area in the United States and Russian space programs (Taylor 1993). Microgravity and stress experienced during space flights results in immune system aberration (Taylor 1993). In ground-based mouse models for some of the microgravity effects on the human body, hindlimb unloading (HU) has been reported to cause abnormal cell proliferation and cytokine production (Armstrong et al., 1993, Chapes et al. 1993). In this report, we document that a nutritional nucleotide supplementation as studied in ground-based microgravity analogs, has potential to serve as a countermeasure for the immune dysfunction observed in space travel.

Animals↗
PubMed1998

The International Space Life Sciences Working Group.

The International Space Life Sciences Working Group (ISLSWG) is made up of representatives from five space agencies: the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), the Canadian Space Agency (CSA), the Centre National d'Etudes Spatiale (CNES), the Deutsches Zentrum fur Luft- und Raumfahrt (DLR, formerly the Deutsche Agentur fur Raumfahrtangelegenheiten or DARA), and the National Space Development Agency of Japan (NASDA). The group met for the first time in 1989, and since that time has developed a Strategic Plan and has taken concrete steps to implement this plan. The result is a closely coordinated international program of Space Life Sciences which will enable optimal utilization of space flight opportunities.

Biological Science Disciplines↗
PubMed1986

Assessing fatigue.

Despite impressive advances in aircraft technology over the past several decades and an overall decline in the airline accident rate since the introduction of turbine-powered aircraft, flight crew performance problems continue to dominate air transport accident statistics. Researchers have offered many hypotheses to explain this finding, and interest in pilot fatigue has stimulated a large volume of laboratory research. Much of this work, however, is difficult to generalize and to apply to the real world of flight operations, and researchers disagree about the extent and operational significance of fatigue-related reductions in pilot performance. As a result, in 1980 Congress asked the National Aeronautics and Space Administration to undertake a comprehensive research program to assess whether fatigue-related problems are prevalent in long- and short-haul flying. The two major goals of this project are: (1) to assess the psychophysiological effects on pilot performance of flying various types of flight and duty cycles, and (2) to determine the operational significance to flight safety and efficiency of flying these flight and duty cycles.

Aerospace Medicine↗
PubMed1989

Subcritical and supercritical water oxidation of CELSS model wastes.

Controlled-Ecological-Life-Support-System (CELSS) model wastes were wet-oxidized at temperatures from 250 to 500 degrees C, i.e., below and above the critical point of water (374 degrees C and 218 kg/cm2 or 21.4 MPa). A solution of ammonium hydroxide and acetic acid and a slurry of human urine, feces, and wipes were used as model wastes. Almost all of the organic matter in the model wastes was oxidized in the temperature range from 400 to 500 degrees C, i.e., above the critical conditions for water. In contrast, only a small portion of the organic matter was oxidized at subcritical conditions. Although the extent of nitrogen oxidation to nitrous oxide (N2O) and/or nitrogen gas (N2) increased with reaction temperature, most of the nitrogen was retained in solution as ammonia near 400 degrees C. This important finding suggests that most of the nitrogen in the waste feed can be retained in solution as ammonia during oxidation at low supercritical temperatures and be subsequently used as a nitrogen source for plants in a CELSS while at the same time organic matter is almost completely oxidized to carbon dioxide and water. It was also found in this study the Hastelloy C-276 alloy reactor corroded during waste oxidation. The rate of corrosion was lower above than below the critical temperature for water.

Acetates↗
PubMed1989

Planetary protection policy overview and application to future missions.

The 1967 treaty on the peaceful uses of outer space reflected both concerns associated with the unknown nature of the space environment and the desire of the world scientific community to preserve the pristine nature of celestial objects until such times as they could be studied in an effective manner. Since 1967, NASA has issued policy directives that have adopted the guidelines of COSPAR for protecting the planets from contamination by Earth organisms and for protecting the Earth from the unknown. This paper presents the current status of planetary protection (quarantine) policy within NASA, and a prospectus on how planetary protection and back contamination issues might be addressed in relation to future missions envisioned for development by NASA either independently, or in cooperation with the space agencies of other nations.

Containment of Biohazards↗
PubMed1992

Planetary Protection Policy (U.S.A.).

Through existing treaty obligations of the United States, NASA is committed to exploring space while avoiding biological contamination of the planets, and to the protection of the Earth against harm from materials returned from space. Because of the similarities between Mars and Earth, plans for the exploration of Mars evoke discussions of these Planetary Protection issues. US Planetary Protection Policy will be focused on the preservation of these goals in an arena that will change with the growth of scientific knowledge about the martian environment. Early opportunities to gain the appropriate data will be used to guide later policy implementation. Because human presence on Mars will result in the end of Earth's separation from the martian environment, it is expected that precursor robotic missions will address critical planetary protection concerns before humans arrive.

Containment of Biohazards↗
PubMed1990

How effectively does a clinostat mimic the ultrastructural effects of microgravity on plant cells?

Columella cells of seedlings of Zea mays L. cv. Bear Hybrid grown in the microgravity of orbital flight allocate significantly larger relative-volumes to hyaloplasm and lipid bodies, and significantly smaller relative-volumes to dictyosomes, plastids, and starch than do columella cells of seedlings grown at 1 g. The ultrastructure of columella cells of seedlings grown at 1 g and on a rotating clinostat is not significantly different. However, the ultrastructure of cells exposed to these treatments differs significantly from that of seedlings grown in microgravity. These results indicate that the actions of a rotating clinostat do not mimic the ultrastructural effects of microgravity in columella cells of Z. mays.

Cell Compartmentation↗
PubMed1991

Conventional and innovative land-based technologies for waste combustion.

This paper is an overview of various land-based technologies for safely treating waste materials. Covered are both the older, proven devices, such as conventional incinerators, as well as some of the new or novel technologies which thus far have found limited application. It is hoped that this paper can provide some degree of guidance to NASA in their search for appropriate systems for waste treatment, disposal, and/or recycling in space mission programs.

Hazardous Waste↗
PubMed1997

Physical examination during space flight.

OBJECTIVE: To develop techniques for conducting a physical examination in microgravity and to describe and document the physiologic changes noted with use of a modified basic physical examination. DESIGN: On the basis of data gathered from physical examinations on KC-135 flights, three physical variables were assessed serially in astronauts during two shuttle missions (of 8- and 10-day duration, respectively). Preflight, in-flight, and postflight examinations were conducted by trained physician-astronauts or flight surgeons, who used this modified examination. MATERIAL AND METHODS: Five male and two female crewmembers participated in the "hands-on" physical examination of all physiologic systems except the genitourinary system. Level of edema, intensity of bowel sounds, and peripheral reflexes were assessed and graded. RESULTS: This investigation identified unique elements of a physical examination performed during space flight that will assist in the development of standard methods for conducting examinations of astronauts in weightlessness. In addition, demonstrable changes induced by microgravity were noted in most physiologic systems examined. CONCLUSION: The data support the hypothesis that the microgravity examination differs from that conducted on earth or in a 1g environment. In addition, alterations in the physiologic response can be detected with use of hands-on technique. These data are invaluable in the development of optimal medical care for humans in space.

Auscultation↗
PubMed1991

Lower body negative pressure to provide load bearing in space.

Presently, exercise protocols and equipment for spaceflight are unresolved, although recent calculations suggest that all exercise in space to date has lacked sufficient loads to maintain preflight musculoskeletal mass. We hypothesized that lower body negative pressure (LBNP) produces a footward force equal to the product of the pressure differential and body cross-sectional area at the waist seal. Twelve male volunteers weighing 67.6-86.9 kg were sealed at the superior iliac crest in upright and supine LBNP chambers. Neither configuration included a saddle, so that the force due to LBNP was transmitted to the feet of our subjects. Each subject was exposed to 10 mm Hg increments of LBNP up to 70 mm Hg (standing) or to 50-100 mm Hg (supine), depending upon individual tolerance. Static reaction force was measured at each LBNP level for approximately 1-2 min. An additional static force approximately equivalent to 1% Earth body weight was generated against the feet by each mm Hg of LBNP either during upright standing or supine posture. Furthermore, the forces measured during LBNP agreed well with forces calculated from the cross-sectional areas of our subjects' waists. These results indicate that exercise in microgravity against 100 mm Hg LBNP could produce static and inertial forces similar in magnitude to those occurring on Earth. This gravity-independent technique may help maintain the musculoskeletal and cardiovascular systems of crewmembers during prolonged exposure to microgravity.

Body Weight↗
PubMed1992

Development of countermeasures for medical problems encountered in space flight.

By the turn of this century, long-duration space missions, either in low Earth orbit or for got early planetary missions, will become commonplace. From the physiological standpoint, exposure to the weightless environment results in changes in body function, some of which are adaptive in nature and some of which can be life threatening. Important issues such as environmental health, radiation protection, physical deconditioning, and bone and muscle loss are of concern to life scientists and mission designers. Physical conditioning techniques such as exercise are not sufficient to protect future space travellers. A review of past experience with piloted missions has shown that gradual breakdown in bone and muscle tissue, together with fluid losses, despite a vigorous exercise regimen can ultimately lead to increased evidence of renal stones, musculoskeletal injuries, and bone fractures. Biological effects of radiation can, over long periods of time increase the risk of cancer development. Today, a vigorous program of study on the means to provide a complex exercise regimen to the antigravity muscles and skeleton is under study. Additional evaluation of artificial gravity as a mechanism to counteract bone and muscle deconditioning and cardiovascular asthenia is under study. New radiation methods are being developed. This paper will deal with the results of these studies.

Aerospace Medicine↗
PubMed1988

Assessment of the efficacy of medical countermeasures in space flight.

Changes in body fluids, electrolytes, and muscle mass are manifestations of adaptation to space flight and readaptation to the 1-g environment. The purposes of this paper are to review the current knowledge of biomedical responses to short- and long-duration space missions and to assess the efficacy of countermeasures to 1-g conditioning. Exercise protocols, fluid hydration, dietary and potential pharmacologic measures are evaluated, and directions for future research activities are recommended.

Adaptation, Physiological↗
PubMed1991

The physiology of spacecraft and space suit atmosphere selection.

The majority of the environmental factors which comprise the spacecraft and space suit environments can be controlled at "Earth normal" values, at optimum values, or at other values decided upon by spacecraft designers. Factors which are considered in arriving at control values and control ranges of these parameters include physiological, engineering, operational cost, and safety considerations. Several of the physiological considerations, including hypoxia and hyperoxia, hypercapnia, temperature regulation, and decompression sickness are identified and their impact on spacecraft and space suit atmosphere selection are considered. The past experience in controlling these parameters in U.S. and Soviet spacecraft and space suits and the associated physiological responses are reviewed. Current areas of physiological investigation relating to environmental factors in spacecraft are discussed, particularly decompression sickness which can occur as a result of change in pressure from Earth to spacecraft or spacecraft to space suit. Physiological considerations for long-term lunar or Martian missions will have different impacts on atmosphere selection and may result in the selection of atmospheres different than those currently in use.

Atmospheric Pressure↗
PubMed1992

Space habitat contaminant growth models.

This paper outlines the need for and role of Contaminant Growth Models (CGM) in designing space habitats and space mission operations. The tremendous complexity of the contamination problem and the current lack of data suggests that a "layered" approach to CGM development and utilization be made in conjunction with medical/toxicological research and risk assessments. Two space habitat contaminant examples: thermodegradation and hydrazine, are utilized to show how such a model might be useful in analyzing the environment of a space habitat. The examples also depict how NASA's interdisciplinary Center for Space Environmental Health (CSEH) will combine medical/toxicological research results with engineering environmental system design tools to set standards and help in the design, prediction, monitoring and safe control of space habitats. Since the CSEH project is just beginning, the contents of the paper are descriptive of the goal and the approach being taken, rather than conclusive in nature.

Ammonia↗
PubMed1989

Sources and processing of CELSS wastes.

The production rate and solid content of waste streams found in a life support system for a space habitat (in which plants are grown for food) are discussed. Two recycling scenarios, derived from qualitative considerations as opposed to quantitative mass and energy balances, tradeoff studies, etc., are presented; they reflect differing emphases on and responses to the waste stream formation rates and their composition, as well as indicate the required products from waste treatment that are needed in a life support system. The data presented demonstrate the magnitude of the challenge to developing a life support system for a space habitat requiring a high degree of closure.

Air Pollutants↗