共查询到20条相似文献,搜索用时 0 毫秒
1.
The GPS satellite data are used to study the dynamics of the ionospheric total electron content (TEC) over Central Europe in the summer season from June 23 to September 30, 1996. The TEC variations within the range of periods typical of the planetary waves were found to be nearly synchronous with the neutral wind variations in the mesosphere and with the variations in the occurrence of ionospheric sporadic layers. The observed TEC variations were interpreted as the result of penetration of energy carried by nonstationary Rossby waves to the upper atmospheric altitudes. 相似文献
2.
The increasing robotic exploration of Mars and eventual human exploration and settlement of that planet threatens to have a significant environmental impact on scientifically important sites and sites of natural beauty in the form of contamination with micro-organisms and spacecraft parts. By definition, the sites that we might wish to preserve are likely to be those to which robots and humans will be sent. An interventionist step to protect pristine regions of Mars with the formation of a Planetary Park system is proposed. Possible locations for the first seven Planetary Parks are suggested. Landing of unmanned craft in these parks would be forbidden. Although global dust storms can carry microorganisms across the planetary surface, the regulations suggested for these parks will allow for the maximum level of preservation. We also suggest that the Planetary Park system could be applied to the Moon. 相似文献
3.
4.
5.
Among of the highlights of the 20th century were flights of spacecraft to other bodies of the Solar System. This paper describes briefly the missions attempted, their goals, and fate. Information is presented in five tables on the missions launched, their goals, mission designations, dates, discoveries when successful, and what happened if they failed. More detailed explanations are given in the accompanying text. It is shown how this enterprise developed and evolved step by step from a politically driven competition to intense scientific investigations and international cooperation. Initially, only the USA and USSR sent missions to the Moon and planets. Europe and Japan joined later. The USSR carried out significant research in Solar System exploration until the end of the 1980s. The Russian Federation no longer supports robotic planetary exploration for economic reasons, and it remains to be seen whether the invaluable Russian experience in planetary space flight will be lost. Collaboration between Russian and other national space agencies may be a solution. 相似文献
6.
星球巡视器任务规划技术发展综述 总被引:1,自引:0,他引:1
首先阐述了星球巡视器任务规划的定义、内容和特点,并分别从任务规划算法、全局路径规划算法、局部路径规划算法三个层面对国内外星球巡视器任务规划技术的研究现状进行了分析和评述。在任务规划层面,当前研究主要集中在基于资源调度的方法和基于路径的方法;在全局路径规划层面,介绍了路径图法、单元分解法等几何模型构建算法以及A*类算法等图搜索算法;在局部路径规划层面,介绍了人工势场法、Bug类算法、启发式动态重规划算法、基于地形评估的算法等几类常用算法。最后,对星球巡视器任务规划技术的未来发展方向进行了展望。 相似文献
7.
Charles S. Cockell 《Space Policy》2005,21(4):287-292
Planetary protection policies designed to reduce the cross-transfer of life on spacecraft from one planet to another can either be formulated from the pragmatic instrumental needs of scientific exploration, or from ethical principles. I address planetary protection concerns by starting from a normative ethical framework for the treatment of microorganisms. This argues that they have intrinsic value at the level of the individual through to the level of the community, but at the individual level this ethic can only be theoretical. This approach yields a solution to the problem of the inevitable contamination of Mars by human explorers and suggests that in some instances the local contamination of other planets may be acceptable. An exception would be where this contamination would cause destruction of microbial ecosystems. Within the framework of such an ethic, the term ‘planetary protection’ may be normatively too narrow and ‘planetary preservation’ may better describe the activity of controlling cross-inoculation of planets. I discuss an example of a contamination event that might be ethically acceptable within the framework of ‘preservation’, but would be regarded as unacceptable under current planetary ‘protection’ guidelines. 相似文献
8.
9.
B. I. Rabinovich 《Cosmic Research》2007,45(5):393-407
This paper continues the series of papers [1–5] and generalizes the previous results to a proto-ring of magnetized plasma whose density decreases in the radial direction. The problem of quantization of the sector and orbital velocities, and of the radii and periods of revolution of elite plasma rings is considered. A new concept of super-elite rings is introduced. Their isomorphism with the orbits of the planets and planetary satellites in the Solar System is proved. This isomorphism also extends to the orbits of electrons in the Bohr’s model of the hydrogen atom. 相似文献
10.
Yasuhiko Aihara 《Acta Astronautica》1984,11(6):313-317
Gasdynamic behavior is supposed to play an important role in the phenomena involved in gaseous stars like Saturn. From this viewpoint the gasdynamic motion in Saturn under the influence of gravity field is analyzed and the results are compared with the data of Saturn observations by Voyager I. The distortions of gravity field are regarded as small disturbance due to the rotation of spherical gaseous stars in view of Saturn having a small oblateness and as a result it is found that a periodic change in gravity potential happens concentrated on the equatorial plane. It is recognized that the positions of Saturn's rings and satellites generally correspond to the wells of the gravity potential. Approximations and speculations for velocity distribution and specific-heat ratio which have to be made in the analysis fortunately seem to have no significant influence on the results of the analysis.Good coincidence between the analysis in this paper and the observation data suggests an effective applicability of gasdynamics to the space science. 相似文献
11.
The process of formation of a particles cloud (space debris) during breakdown of the Earth’s Artificial Satellite (EAS) is considered. A system of equations of motion is derived, and its analytical solution in the linear approximation for circular orbits is presented. The distinction between this solution and an exact numerical solution is indicated. The cases of satellite breakdown at the apogee and perigee on an elliptic orbit are also considered, and some characteristics of these processes are compared.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 4, 2005, pp. 269–273.Original Russian Text Copyright © 2005 by Gorelov, Zarubkin. 相似文献
12.
A system of two space bases housing missiles for an efficient Planetary Defense of the Earth from asteroids and comets was firstly proposed by this author in 2002. It was then shown that the five Lagrangian points of the Earth–Moon system lead naturally to only two unmistakable locations of these two space bases within the sphere of influence of the Earth. These locations are the two Lagrangian points L1 (in between the Earth and the Moon) and L3 (in the direction opposite to the Moon from the Earth). In fact, placing missiles based at L1 and L3 would enable the missiles to deflect the trajectory of incoming asteroids by hitting them orthogonally to their impact trajectory toward the Earth, thus maximizing the deflection at best. It was also shown that confocal conics are the only class of missile trajectories fulfilling this “best orthogonal deflection” requirement.The mathematical theory developed by the author in the years 2002–2004 was just the beginning of a more expanded research program about the Planetary Defense. In fact, while those papers developed the formal Keplerian theory of the Optimal Planetary Defense achievable from the Earth–Moon Lagrangian points L1 and L3, this paper is devoted to the proof of a simple “(small) asteroid deflection law” relating directly the following variables to each other:
- (1) the speed of the arriving asteroid with respect to the Earth (known from the astrometric observations);
- (2) the asteroid's size and density (also supposed to be known from astronomical observations of various types);
- (3) the “security radius” of the Earth, that is, the minimal sphere around the Earth outside which we must force the asteroid to fly if we want to be safe on Earth. Typically, we assume the security radius to equal about 10,000 km from the Earth center, but this number might be changed by more refined analyses, especially in the case of “rubble pile” asteroids;
- (4) the distance from the Earth of the two Lagrangian points L1 and L3 where the defense missiles are to be housed;
- (5) the deflecting missile's data, namely its mass and especially its “extra-boost”, that is, the extra-energy by which the missile must hit the asteroid to achieve the requested minimal deflection outside the security radius around the Earth.
- (1) In the vicinity of the Earth, the hyperbola of the arriving asteroid is nearly the same as its own asymptote, namely, the asteroid's hyperbola is very much like a straight line. We call this approximation the line/circle approximation. Although “rough” compared to the ordinary Keplerian theory, this approximation simplifies the mathematical problem to such an extent that two simple, final equations can be derived.
- (2) The confocal missile trajectory, orthogonal to this straight line, ceases then to be an ellipse to become just a circle centered at the Earth. This fact also simplifies things greatly. Our results are thus to be regarded as a good engineering approximation, valid for a preliminary astronautical design of the missiles and bases at L1 and L3.
- (1) taking into account many perturbation forces of all kinds acting on both the asteroids and missiles shot from L1 and L3;
- (2) adding more (non-optimal) trajectories of missiles shot from either the Lagrangian points L4 and L5 of the Earth–Moon system or from the surface of the Moon itself;
- (3) encompassing the full range of missiles currently available to the USA (and possibly other countries) so as to really see “which missiles could divert which asteroids”, even just within the very simplified scheme proposed in this paper.
13.
The problem of optimization of the interplanetary flight Earth–Mars–Earth is formulated with restrictions on the total duration of this mission and with taking the ellipticity and noncoplanarity of planetary orbits into account. An iteration scheme for solving the problem is developed, which is based on applying a sequence of flight models with increasing complexity. An approach to choosing the points of mating the planetocentric and heliocentric trajectory segments is suggested. The influence of the errors of method of the model on the results of optimization is estimated. Software tools are developed, and full computer start-to-finish simulation of the flight is carried out with graphic representation of the trajectory segments. 相似文献
14.
We have been studying the survival rates of some species of terrestrial unicellular and multicellular organism (viruses, bacteria, yeasts, fungi, algae, etc.) under simulated interstellar conditions, in connection with planetary quarantine. The interstellar environment in the solar system has been simulated by low temperature, high vacuum (77 K, 4 x 10(-8) torr), and proton irradiation from a Van de Graaff generator. After exposure to a barrage of protons corresponding to about 250 years of irradiation in solar space, tobacco mosaic virus, Bacillus subtilis spores, Staphylococcus aureus, Micrococcus flavus, Aspergillus niger spores, and Clostridium mangenoti spores showed survival rates of 82, 45, 74, 13, 28, and 25%, respectively. 相似文献
15.
16.
B. N. Korchuganov G. G. Dol'nikov M. V. Gerasimov O. F. Prilutskii R. Rider G. Waenke T. Economou 《Cosmic Research》2004,42(1):19-22
A theoretical and experimental feasibility study of possible determination of the hydrogen and deuterium concentrations in the surface layers of planetary bodies is presented. The method under study is the recoil proton and deuteron spectrometry of forward scattering in the course of elastic interaction of alpha particles with the nuclei of hydrogen isotopes. The spectra of recoil protons and deuterons were recorded using a prototype model of a hydrogen spectrometer, and these spectra were used to determine the hydrogen concentrations in the samples of different compositions. 相似文献
17.
This paper deals with a system simulating a steady electromagnetic plasma thruster with an azimuthal electron drift. An adequate model of the mixture plasma and condensed particles due to erosion is formulated to study the problem of acceleration. 相似文献
18.
This is a theoretical study of the nonequilibrium motion of charged particles in an electric field of solitons. We show that the self-consistent electric field of ion-acoustic and electron-acoustic solitons is characterized by one-way transfer of charged particles at a distance of several Debye radii. The dependence of relevant local currents on the amplitude of solitons is determined. We consider the practically important case of a moving cascade consisting of many solitons and show that the induced currents have a significant constant component. The kinetic energy acquired by charged particles in the soliton field is calculated. The temporal resolution required for the recording of soliton-induced currents is estimated. The calculations presented here can be used to interpret the results of experiments conducted to study solitons in the space plasma. 相似文献
19.
20.
A dispersion equation is derived for small disturbances of the magnetohydrodynamic type in optically transparent plasma with cosmic abundance of elements. The electron heat conductivity along the magnetic field and proton heat conductivity across the field are taken into account. It is shown that entropy waves increase exponentially in wide ranges of temperatures and densities of the cosmic plasma. Manifestations of instability of the entropy waves in the cosmic plasma are discussed. 相似文献