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61.
I Vernós M Carratalá J González-Jurado J R Valverde M Calleja A Domingo J Vinós M Cervera R Marco 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1989,9(11):137-146
Gravity and radiation are undoubtedly the two major environmental factors altered in space. Gravity is a weak force, which creates a permanent potential field acting on the mass of biological systems and their cellular components, strongly reduced in space flights. Developmental systems, particularly at very early stages, provide the larger cellular compartments known, where the effects of alterations in the size of the gravity vector on living organisms can be more effectively tested. The insects, one of the more highly evolved classes of animals in which early development occurs in a syncytial embryo, are systems particularly well suited to test these effects and the specific developmental mechanisms affected. Furthermore, they share some basic features such as small size, short life cycles, relatively high radio-resistance, etc. and show a diversity of developmental strategies and tempos advantageous in experiments of this type in space. Drosophila melanogaster, the current biological paradigm to study development, with so much genetic and evolutionary background available, is clearly the reference organism for these studies. The current evidence on the effects of the physical parameters altered in space flights on insect development indicate a surprising correlation between effects seen on the fast developing and relatively small Drosophila embryo and the more slowly developing and large Carausius morosus system. In relation to the issue of the importance of developmental and environmental constraints in biological evolution, still the missing link in current evolutionary thinking, insects and space facilities for long-term experiments could provide useful experimental settings where to critically assess how development and evolution may be interconnected. Finally, it has to be pointed out that since there are experimental data indicating a possible synergism between microgravity and space radiation, possible effects of space radiation should be taken into account in the planning and evaluation of experiments designed to test the potential role of microgravity on biological developmental and evolution. 相似文献
62.
J Oró T Mills A Lazcano 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(3):81-90
The notion that comets supplied the primitive Earth with the requisite chemical species for the process of chemical evolution, which is widely held to have led to the origin of life on Earth, has now gained considerable intellectual momentum since its first formulation in 1961. In fact, in the fall of 1991, the University of Wisconsin-Eau Claire hosted a well attended scientific meeting devoted solely to the discussion of this topic, entitled Comets and the Origin and Evolution of Life [see Special Issue of Origins of Life, P.J. Thomas (ed), vol. 21(5-6)]. As a result of the above meeting, the recently completed COSPAR/World Space Congress Symposium on Extraterrestrial Organic Chemistry and the Origins of Life, and numerous independent reports, the role of comets in the Earth's biogenesis has been thoroughly addressed in the literature. At this time, in light of a few recent findings, we present here a concise review of this topic together with a brief discussion of the possible role of cometary material in the origin of life elsewhere in the Universe. 相似文献
63.
A. Rimóczi-Paál 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(6):329-332
For the investigation of radiative properties of clouds using satellite images an objective parameter is required which is independent of conditions of illumination and of recorders. We found a new parameter - the relative brightness - which seems to serve this purpose. Using the relative brightness the daily amount of surface global radiation can be determined easily by linear regression with sufficient accuracy from METEOSAT images. Period between November 1981 and July 1983 was studied and our results are not worse than the ones using more complicated methods. 相似文献
64.
65.
This is a slightly edited version of the IAA's recently published interdisciplinary and international study on managing the traffic—of all manifestations—in outer space. The study examines the requirements and prospects for managing space traffic in the future and provides a thorough analysis of the status of ways and means of doing so, as well as a comprehensive to-do list for organizations like COPUOS and ICAO. 相似文献
66.
McKay CP Friedmann EI Gómez-Silva B Cáceres-Villanueva L Andersen DT Landheim R 《Astrobiology》2003,3(2):393-406
The Atacama along the Pacific Coast of Chile and Peru is one of the driest and possibly oldest deserts in the world. It represents an extreme habitat for life on Earth and is an analog for life in dry conditions on Mars. We report on four years (September 1994-October 1998) of climate and moisture data from the extreme arid region of the Atacama. Our data are focused on understanding moisture sources and their role in creating suitable environments for photosynthetic microorganisms in the desert surface. The average air temperature was 16.5 degrees C and 16.6 degrees C in 1995 and 1996, respectively. The maximum air temperature recorded was 37.9 degrees C, and the minimum was -5.7 degrees C. Annual average sunlight was 336 and 335 W m(-2) in 1995 and 1996, respectively. Winds averaged a few meters per second, with strong f?hn winds coming from the west exceeding 12 m s(-1). During our 4 years of observation there was only one significant rain event of 2.3 mm, which occurred near midnight local time. We suggest that this event was a rainout of a heavy fog. It is of interest that the strong El Ni?o of 1997-1998 brought heavy rainfall to the deserts of Peru, but did not bring significant rain to the central Atacama in Chile. Dew occurred at our station frequently following high nighttime relative humidity, but is not a significant source of moisture in the soil or under stones. Groundwater also does not contribute to surface moisture. Only the one rain event of 2.3 mm resulted in liquid water in the soil and beneath stones for a total of only 65-85 h over 4 years. The paucity of liquid water under stones is consistent with the apparent absence of hypolithic (under-stone) cyanobacteria, the only known primary producers in such extreme deserts. 相似文献
67.
Chemical evolution of primitive solar system bodies. 总被引:1,自引:0,他引:1
J Oró T Mills 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1989,9(2):105-120
In this paper we summarize some of the most salient observations made recently on the organic molecules and other compounds of the biogenic elements present in the interstellar medium and in the primitive bodies of the solar system. They include the discovery of the first phosphorus molecular species in dense interstellar clouds, the presence of complex organic ions in the dust and gas phase of Halley's coma, the finding of unusual, probably presolar, deuterium-hydrogen ratios in the amino acids of carbonaceous chondrites, and new developments on the chemical evolution of Titan, the primitive Earth, and early Mars. Some of the outstanding problems concerning the synthesis of organic molecules on different cosmic bodies are also discussed from an exobiological perspective. 相似文献
68.
H. Kunow M.A. Lee L.A. Fisk R.J. Forsyth B. Heber T.S. Horbury E. Keppler J. Kóta Y.-Q. Lou R.B. McKibben C. Paizis M.S. Potgieter E.C. Roelof T.R. Sanderson G.M. Simnett R. Von Steiger B.T. Tsurutani R.F. Wimmer-Schweingruber J.R. Jokipii 《Space Science Reviews》1999,89(1-2):221-268
Ulysses observed a stable strong CIR from early 1992 through 1994 during its first journey into the southern hemisphere. After
the rapid latitude scan in early 1995, Ulysses observed a weaker CIR from early 1996 to mid-1997 in the northern hemisphere
as it traveled back to the ecliptic at the orbit of Jupiter. These two CIRs are the observational basis of the investigation
into the latitudinal structure of CIRs. The first CIR was caused by an extension of the northern coronal hole into the southern
hemisphere during declining solar activity, whereas the second CIR near solar minimum activity was caused by small warps in
the streamer belt. The latitudinal structure is described through the presentation of three 26-day periods during the southern
CIR. The first at ∼24°S shows the full plasma interaction region including fast and slow wind streams, the compressed shocked
flows with embedded stream interface and heliospheric current sheet (HCS), and the forward and reverse shocks with associated
accelerated ions and electrons. The second at 40°S exhibits only the reverse shock, accelerated particles, and the 26-day
modulation of cosmic rays. The third at 60°S shows only the accelerated particles and modulated cosmic rays. The possible
mechanisms for the access of the accelerated particles and the CIR-modulated cosmic rays to high latitudes above the plasma
interaction region are presented. They include direct magnetic field connection across latitude due to stochastic field line
weaving or to systematic weaving caused by solar differential rotation combined with non-radial expansion of the fast wind.
Another possible mechanism is particle diffusion across the average magnetic field, which includes stochastic field line weaving.
A constraint on connection to a distant portion of the CIR is energy loss in the solar wind, which is substantial for the
relatively slow-moving accelerated ions. Finally, the weaker northern CIR is compared with the southern CIR. It is weak because
the inclination of the streamer belt and HCS decreased as Ulysses traveled to lower latitudes so that the spacecraft remained
at about the maximum latitudinal extent of the HCS.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
69.
Silvia Martínez-Núñez Peter Kretschmar Enrico Bozzo Lidia M. Oskinova Joachim Puls Lara Sidoli Jon Olof Sundqvist Pere Blay Maurizio Falanga Felix Fürst Angel Gímenez-García Ingo Kreykenbohm Matthias Kühnel Andreas Sander José Miguel Torrejón Jörn Wilms 《Space Science Reviews》2017,212(1-2):59-150
Massive stars, at least \(\sim10\) times more massive than the Sun, have two key properties that make them the main drivers of evolution of star clusters, galaxies, and the Universe as a whole. On the one hand, the outer layers of massive stars are so hot that they produce most of the ionizing ultraviolet radiation of galaxies; in fact, the first massive stars helped to re-ionize the Universe after its Dark Ages. Another important property of massive stars are the strong stellar winds and outflows they produce. This mass loss, and finally the explosion of a massive star as a supernova or a gamma-ray burst, provide a significant input of mechanical and radiative energy into the interstellar space. These two properties together make massive stars one of the most important cosmic engines: they trigger the star formation and enrich the interstellar medium with heavy elements, that ultimately leads to formation of Earth-like rocky planets and the development of complex life. The study of massive star winds is thus a truly multidisciplinary field and has a wide impact on different areas of astronomy.In recent years observational and theoretical evidences have been growing that these winds are not smooth and homogeneous as previously assumed, but rather populated by dense “clumps”. The presence of these structures dramatically affects the mass loss rates derived from the study of stellar winds. Clump properties in isolated stars are nowadays inferred mostly through indirect methods (i.e., spectroscopic observations of line profiles in various wavelength regimes, and their analysis based on tailored, inhomogeneous wind models). The limited characterization of the clump physical properties (mass, size) obtained so far have led to large uncertainties in the mass loss rates from massive stars. Such uncertainties limit our understanding of the role of massive star winds in galactic and cosmic evolution.Supergiant high mass X-ray binaries (SgXBs) are among the brightest X-ray sources in the sky. A large number of them consist of a neutron star accreting from the wind of a massive companion and producing a powerful X-ray source. The characteristics of the stellar wind together with the complex interactions between the compact object and the donor star determine the observed X-ray output from all these systems. Consequently, the use of SgXBs for studies of massive stars is only possible when the physics of the stellar winds, the compact objects, and accretion mechanisms are combined together and confronted with observations.This detailed review summarises the current knowledge on the theory and observations of winds from massive stars, as well as on observations and accretion processes in wind-fed high mass X-ray binaries. The aim is to combine in the near future all available theoretical diagnostics and observational measurements to achieve a unified picture of massive star winds in isolated objects and in binary systems. 相似文献
70.
M. Scholer G. Mann S. Chalov M.I. Desai L.A. Fisk J.R. Jokipii R. Kallenbach E. Keppler J. Kóta H. Kunow M.A. Lee T.R. Sanderson G.M. Simnett 《Space Science Reviews》1999,89(1-2):369-399
On the basis of the observational picture established in the report of Mason, von Steiger et al. (1999) the status of theoretical models on origin, injection, and acceleration of particles associated with Corotating Interaction
Regions (CIRs) is reviewed. This includes diffusive or first-order Fermi acceleration at oblique shocks, adiabatic deceleration
in the solar wind, stochastic acceleration in Alfvén waves and oblique propagating magnetosonic waves, and shock surfing as
possible injection mechanism to discriminate pickup ions from solar wind ions.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献