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311.
K Dose A Bieger-Dose R Dillmann M Gill O Kerz A Klein C Stridde 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(12):51-60
The response of spores of Bacillus subtilis, cells of Deinococcus radiodurans and conidia of Aspergillus ochraceus to actual and simulated space conditions (UV in combination with long-term exposure to extremely dry conditions, including vacuum) has been studied: The following effects have been analyzed: decrease of viability, occurrence of DNA double strand breaks, formation of DNA-protein cross-links and DNA-DNA cross-links. All organisms show an increased sensitivity to UV light in extreme dryness (dry argon or vacuum) compared to an irradiation in aqueous suspension. The UV irradiation leads in all cases to a variety of DNA lesions. Very conspicuous is the occurrence of double strand breaks. Most of these double strand breaks are produced by incomplete repair of other lesions, especially base damages. The increase in DNA lesions can be correlated to the loss in viability. The specific response of the chromosomal DNA to UV irradiation in extreme dryness, however, varies from species to species and depends on the state of dehydration. The formation of DNA double strand breaks and DNA-protein cross-links prevails in the case of B. subtilis spores. In cells of Deinococcus radiodurans DNA-DNA cross-links often predominate, in conidia of Aspergillus ochraceus double strand breaks. The results obtained by direct exposure to space conditions (EURECA mission and D2 mission) largely agree with the laboratory data. 相似文献
312.
Editorial comment 总被引:1,自引:0,他引:1
313.
M A Schneegurt B Arieli S S Nielsen P R Trumbo L A Sherman 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(4-5):177-180
Controlled ecological life support systems (CELSS) have been proposed to make long-duration manned space flights more cost-effective. Higher plants will presumably provide food and a breathable atmosphere for the crew. It has been suggested that imbalances between the CO2/O2 gas exchange ratios of the heterotrophic and autotrophic components of the system will inevitably lead to an unstable system, and the loss of O2 from the atmosphere. Ratio imbalances may be corrected by including a second autotroph with an appropriate CO2/O2 gas exchange ratio. Cyanothece sp. ATCC 51142 is a large unicellular N2-fixing cyanobacterium, exhibiting high growth rates under diverse physiological conditions. A rat-feeding study showed the biomass to be edible. Furthermore, it may have a CO2/O2 gas exchange ratio that theoretically can compensate for ratio imbalances. It is suggested that Cyanothece spp. could fulfill several roles in a CELSS: supplementing atmosphere recycling, generating fixed N from the air, providing a balanced protein supplement, and protecting a CELSS in case of catastrophic crop failure. 相似文献
314.
Yu. I. Yermolaev A. A. Petrukovich L. M. Zelenyi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(12):2695-2700
We use ion distribution measurements with CORALL instrument on-board the INTERBALL/Tail spacecraft to study plasma flows in the mid-tail (−9> X> −27 RE) plasma sheet. Three velocity components computed every 2 minutes exhibit two types of velocity variations: Earthward bursty bulk flows (BBFs) and random flow fluctuations. Their properties are in a good agreement with the observations of the ISEE-2 spacecraft (Borovsky et al., 1997). The INTERBALL/Tail spacecraft configuration favors measurements of Vz component, in contrast to previous experiments in which only Vx and Vy were measured reliably. In the outer part of the plasma sheet Vy and Vz fluctuations were close to each other (variances σ(Vy) and σ(Vz) were about 160 and 110 km/s, respectively), but in the inner part at the dusk flank amplitude of Vy fluctuations increased and was 2 times higher than that of Vz component. This asymmetry of fluctuations should be taken into account during modern theoretical analysis and simulations. 相似文献
315.
P.S. Babcock D.M. Auslander R.C. Spear 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):263-270
Reliability of closed life support systems will depend on their ability to continue supplying the crew's needs in the face of perturbations and equipment failures. These dynamic considerations interact with the basic static (equilibrium) design through the sizing of storages, the specification of excess capacities in processors, and the choice of system initial state (total mass in the system). This paper uses a very simple system flow model to examine the possibilities for system failures even when there is sufficient storage to buffer the immediate effects of the perturbation. Two control schemes are shown which have different dynamic consequences in response to component failures. 相似文献
316.
317.
V. I. Moroz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(12):113-121
There is important progress now in the identifications and measurements of primary (parent) molecules in the inner coma of Comet Halley. H2O, CO2 and CO are definitely in the list, CH and some complicate organic molecules are suspected. Gas production rate for water vapor is QH2O 1030 s−1. The bulk of data doesn't contradict to the Whipple model of nucleus (with clathrate modification). Pronounced spatial structure of gaseous flow in the coma was observed, but in general measured properties of neutral gas in the coma of Comet Halley are not very different from predicted. Situation for dust is different. In situ dust measurements show that size spectrum and optical properties of particles in coma are substantively declining from predicted on the base of groundbased photometry. However there are discrepancies between Vega and Giotto dust counter data. Dust in the inner coma didn't prevent the succesful imaging of nucleus by TV on Vega 1 and 2. 相似文献
318.
B V Worgul W Krebs J P Koniarek 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1989,9(10):315-323
Efforts to assess radiation risk in space have been complicated by the considerable unknowns regarding the biological effects of the heavy ion component (HZE particles) of the cosmic rays. The attention has focused primarily on the assignation of a quality factor (Q) which would take into account the greater effectiveness of heavy ions vis-a-vis other forms of ionizing radiation. If however, as the so-called "Microlesion Theory" allows, the passage of HZE particles through living tissue produces unique biological damage, the traditional use of Q becomes meaningless. Therefore, it is critical to determine if microlesions, in fact, do exist. While the concept does not necessarily require detectable morphological damage, "tunnel-lesions" or holes in ocular tissues have been cited as evidence of microlesions. These data, however, are open to reinterpretation. On-going light, scanning and transmission electron microscopic studies of the corneas, lenses and retinas of rat eyes exposed to 450 MeV/amu 56Fe ions thus far have not revealed tunnel-lesion damage. The morphological effects of the heavy ions have been found to be qualitatively similar to the changes following other kinds of ionizing radiation. 相似文献
319.
R. Jager J. Heise J. J. M. in ''t Zand A. C. Brinkman 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):315-318
SAX is an Italian X-ray satellite with a Dutch contribution that will be placed in orbit in 1994. The prime scientific object of SAX is to cover an energy bandwidth that ranges from 0.1 keV up to 200 keV. Among other instruments, SAX will consist of two X-ray Wide Field Cameras built by the Space Research Organisation Netherlands at Utrecht. The WFCs are based on the coded mask principle, the reconstruction of the image takes place on ground. The field of view is 20 degrees square full width at half maximum (FWHM), the angular resolution 5 arcminutes (FWHM) and the energy band ranges from 1.8 to 30 keV with a resolution of 18% at 6 keV. The sensitive area is 200 cm2 at 6 keV. The mask pattern is based on a pseudo random array with 255 × 257 elements of 1 mm2, 50% of which are transparent. 相似文献
320.
R. L. Arnoldy L. J. Cahill Jr P. M. Kintner T. E. Moore C. J. Pollock 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(12):1-7
Data from ARCS rocket ion beam injection experiments will be primarily discussed in this paper. There are three results from this series of active experiments that are of particular interest in space plasma physics. These are the transverse acceleration of ambient ions in the large beam volume, the scattering of beam ions near the release payload, and the possible acceleration of electrons very close to the plasma generator which produce intense high frequency waves. The ability of 100 ma ion beam injections into the upper E and F regions of the ionosphere to produce these phenomena appear to be related solely to the process by which the plasma release payload and the ion beam are neutralized. Since the electrons in the plasma release do not convect with the plasma ions, the neutralization of both the payload and beam must be accomplished by large field-aligned currents (milliamperes/square meter) which are very unstable to wave growth of various modes. Future work will concentrate on the wave production and wave-particle interactions that produce the plasma/energetic particle effects discussed in this paper and which have direct application to natural phenomena in the upper ionosphere and magnetosphere. 相似文献