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571.
In November 2000, the National Aeronautics and Space Administration (NASA) and its partners in the International Space Station (ISS) ushered in a new era of space flight: permanent human presence in low-Earth orbit. As the culmination of the last four decades of human space flight activities. the ISS focuses our attention on what we have learned to date. and what still must be learned before we can embark on future exploration endeavors. Space medicine has been a primary part of our past success in human space flight, and will continue to play a critical role in future ventures. To prepare for the day when crews may leave low-Earth orbit for long-duration exploratory missions, space medicine practitioners must develop a thorough understanding of the effects of microgravity on the human body, as well as ways to limit or prevent them. In order to gain a complete understanding and create the tools and technologies needed to enable successful exploration. space medicine will become even more of a highly collaborative discipline. Future missions will require the partnership of physicians, biomedical scientists, engineers, and mission planners. This paper will examine the future of space medicine as it relates to human space exploration: what is necessary to keep a crew alive in space, how we do it today, how we will accomplish this in the future, and how the National Aeronautics and Space Administration (NASA) plans to achieve future goals. 相似文献
572.
V. Formisano V.I. Moroz H. Hirsch P. Orleanski G. Michel J. Lopez-Moreno E. Amata G. Bellucci G. Piccioni G. Chionchio A. Carusi A. Coradini P. Cerroni M.T. Capria F. Capaccioni A. Adriani M. Vitterbini F. Angrilli G. Bianchini B. Saggin S. Fonti E. Bussoletti D. Mancini L. Colangeli A. Grigoriev B. Moshkin V. Gnedykh I.A. Matsygorin D. Patsaev Yu.V. Nikolsky D.V. Titov L.V. Zasova I. Khatuntsev A. Kiselev G. Arnold H. Driesher M.I. Blecka R. Rodrigo J. Rodriguez-Gomez 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(12):61-64
Thin films containing a mixture of aliphatic (glycine) and aromatic (tryptophan or tyrosine) amino acids were exposed to a vacuum ultraviolet radiation (VUV) with wavelenghts 100–200 nm. Dipeptides (glycyl-tryptophan and glycyl-tyrosine) were synthesized in these conditions. We compared the actions of VUV and γ-radiation. Polymerization is an essential step in prebiological evolution and we have shown that this stage probably occured over an early Solar system history. 相似文献
573.
G D Badhwar P M O'Neill 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):749-757
As the human exploration of space has received new attention in the United States, studies find that exposure to space radiation could adversely impact the mission design. Galactic Cosmic Radiation (GCR), with its very wide range of charges and energies, is particularly important for a mission to Mars, because it imposes a stiff mass penalty for spacecraft shielding. Dose equivalent versus shielding thickness calculations, show a rapid initial drop in exposure with thickness, but an asymptotic behavior at a higher shielding thickness. Uncertainties in the radiobiology are largely unknown. For a fixed radiation risk, this leads to large uncertain ties in shielding thickness for small uncertainties in estimated dose. In this paper we investigate the application of steady-state, spherically-symmetric diffusion-convection theory of solar modulation to individual measurements of differential energy spectra from 1954 to 1989 in order to estimate the diffusion coefficient, kappa (r,t), as a function of time. We have correlated the diffusion coefficient to the Climax neutron monitor rates and show that, if the diffusion coefficient can be separated into independent functions of space and time: kappa (-r,t)=K(t)kappa 0 beta P kappa 1(r), where beta is the particle velocity and P the rigidity, then (i) The time dependent quantity 1/K(t), which is proportional to the deceleration potential, phi(r,t), is linearly related to the Climax neutron monitor counting rate. (ii) The coefficients obtained from hydrogen or helium intensity measurements are the same. (iii) There are different correlation functions for odd and even solar cycles. (iv) The correlation function for the Climax neutron monitor counting rate for given time, t, can be used to estimate mean deceleration parameter phi(t) to within +/- 15% with 90% confidence. We have shown that kappa(r,t) determined from hydrogen and/or helium data, can be used to fit the oxygen and iron differential energy spectra with a root mean square error of about +/- 10%, and essentially independent of the particle charge or energy. We have also examined the ion chamber and 14C measurements which allow the analysis to be extended from the year 1906 to 1990. Using this model we have defined reference GCR spectra at solar minimum and solar maximum. These can be used for space exploration studies and provide a quantitative estimate of the error in dose due to changes in GCR intensities. 相似文献
574.
K. Kudela V. N. Lutsenko D. G. Sibeck M. Slivka T. V. Gretchko E. T. Sarris 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(12):2849-2854
Time period from October 1996 until January 1998 was checked on high energy resolution DOK2 energetic particle instrument measurements on Interball-1 and Interball-2 for the ion (> 20 keV) dispersive events (EDIS) with the exclusion of Interball-1 orbit parts in the tail. A variety of energy dispersive events, both in ion and electron spectra with different duration is found in the auroral regions, in the outer magnetosphere and near the cusp. While EDIS were observed in all sectors of MLT, the best conditions for their observation were in the afternoon local time. The characteristics of dispersive events observed by DOK2 are consistent with their explanation by the gradient-curvature drift of particles from the injection point(s) in the night local time sector given in Lutsenko at al., 2000a, b. 相似文献
575.
The Indian Space Program is described. The main objectives of the program are to provide operation space services to the nation, especially in the fields of communications and remote sensing, and to use modern space technology for the benefit of the Indian people. Some applications of the Indian Space Program are remote sensing, imagery, communications, broadcasting, and surveys of natural resources for water, crop, forest, land, minerals, and ocean. The emphasis is on the development and operation of indigenous satellites and launch vehicles for providing these space services 相似文献
576.
577.
Zhu Jiang Abimael F D Loula Laboratório Nacional de Computaco Científica MCT Av Getúlio Vargas Petrópolis RJ Brazil 《南京航空航天大学学报(英文版)》2001,18(Z1)
INTRODUCTIONThe stationary incompressible Navier- Stokesequations in the primitive variables( velocity uand pressure p)- vΔu + u . u + p =f . u =0u =g inΩinΩonΓ( 1 )whereΩ is a set of R2 ,Γ its boundary,v thekinematic viscosity of the fluid,f a field of givenbody forces,and g a given field defined onΓ sa-tisfying the global conservation property∫Γg . n =0 ( 2 )n denotes the unit outer normal vector toΓ.The vorticity- velocity system of Eq.( 1 ) ,byintroducing the vorticityω… 相似文献
578.
Scoles D.L. Hayden J.W. Pickett D.F. Jr. Rao G.M. 《Aerospace and Electronic Systems Magazine, IEEE》1996,11(7):27-30
A nickel cadmium cell system which utilizes a polypropylene separator impregnated with polybenzimadazole, and which shows promise of providing an aerospace battery with performance equivalent to Super NiCd, and yet is more cost effective, is described. Background information, cell construction information, detailed test program information and data, and status of qualification are given 相似文献
579.
D L Mykles 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,17(6-7):201-204
Atrophy of skeletal muscles is a serious problem in a microgravity environment. It is hypothesized that the unloading of postural muscles, which no longer must resist gravity force, causes an accelerated breakdown of contractile proteins, resulting in a reduction in muscle mass and strength. A crustacean model using the land crab, Gecarcinus lateralis, to assess the effects of spaceflight on protein metabolism is presented. The model is compared to a developmentally-regulated atrophy in which a premolt reduction in muscle mass allows the withdrawal of the large claws at molt. The biochemical mechanisms underlying protein breakdown involves both Ca(2+)-dependent and multicatalytic proteolytic enzymes. Crustacean claw muscle can be used to determine the interactions between shortening and unloading at the molecular level. 相似文献
580.
Bhanu B. Das S. Roberts B. Duncan D. 《IEEE transactions on aerospace and electronic systems》1996,32(3):875-897
An airborne vehicle such as a rotorcraft must avoid obstacles like antennas, towers, poles, fences, tree branches, and wires strung across the flight path. Automatic detection of the obstacles and generation of appropriate guidance and control actions for the vehicle to avoid these obstacles would facilitate autonomous navigation. The requirements of an obstacle detection system for rotorcraft in low-altitude Nap-of-the-Earth (NOE) flight based on various rotorcraft motion constraints is analyzed here in detail. It is argued that an automated obstacle detection system for the rotorcraft scenario should include both passive and active sensors to be effective. Consequently, it introduces a maximally passive system which involves the use of passive sensors (TV, FLIR) as well as the selective use of an active (laser) sensor. The passive component is concerned with estimating range using optical flow-based motion analysis and binocular stereo. The optical flow-based motion analysis that is combined with on-board inertial navigation system (INS) to compute ranges to visible scene points is described. Experimental results obtained using land vehicle data illustrate the particular approach to motion analysis 相似文献