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151.
A. A. Baranov A. F. B. de Prado V. Yu. Razumny Anatoly A. BaranovJr. 《Cosmic Research》2011,49(3):269-279
Four types of optimal solutions are demonstrated to exist for transfers (time of flight is not fixed) between close near-circular
coplanar orbits. One solution is realized with the help of fixed orientation of the propulsion system (PS) along a transversal
in the orbital coordinate system. Another is reached at fixed orientation of the PS in the inertial coordinate system. The
third and fourth types of solutions change the PS orientation in the process of executing the maneuver. Regions of existence
are established for all types of solutions, and algorithms for determination of parameters of these maneuvers are suggested.
The algorithms were used to calculate parameters of the maneuvers of transfer from a launching orbit to a working Sun-synchronous
orbit, and to calculate the maneuvers of supporting the parameters of such an orbit in a specified range. 相似文献
152.
Vytenis M. Vasyliūnas 《Space Science Reviews》2011,158(1):91-118
Many widely used methods for describing and understanding the magnetosphere are based on balance conditions for quasi-static
equilibrium (this is particularly true of the classical theory of magnetosphere/ionosphere coupling, which in addition presupposes
the equilibrium to be stable); they may therefore be of limited applicability for dealing with time-variable phenomena as
well as for determining cause-effect relations. The large-scale variability of the magnetosphere can be produced both by changing
external (solar-wind) conditions and by non-equilibrium internal dynamics. Its developments are governed by the basic equations
of physics, especially Maxwell’s equations combined with the unique constraints of large-scale plasma; the requirement of
charge quasi-neutrality constrains the electric field to be determined by plasma dynamics (generalized Ohm’s law) and the
electric current to match the existing curl of the magnetic field. The structure and dynamics of the ionosphere/magnetosphere/solar-wind
system can then be described in terms of three interrelated processes: (1) stress equilibrium and disequilibrium, (2) magnetic
flux transport, (3) energy conversion and dissipation. This provides a framework for a unified formulation of settled as well
as of controversial issues concerning, e.g., magnetospheric substorms and magnetic storms. 相似文献
153.
154.
Yuichiro Ezoe Tomoki Kimura Satoshi Kasahara Atsushi Yamazaki Kazuhisa Mitsuda Masaki Fujimoto Yoshizumi Miyoshi Graziella Branduardi-Raymont Kumi Ishikawa Ikuyuki Mitsuishi Tomohiro Ogawa Takuya Kakiuchi Takaya Ohashi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
For the future Japanese exploration mission of the Jupiter’s magnetosphere (JMO: Jupiter Magnetospheric Orbiter), a unique instrument named JUXTA (Jupiter X-ray Telescope Array) is being developed. It aims at the first in-situ measurement of X-ray emission associated with Jupiter and its neighborhood. Recent observations with Earth-orbiting satellites have revealed various X-ray emission from the Jupiter system. X-ray sources include Jupiter’s aurorae, disk emission, inner radiation belts, the Galilean satellites and the Io plasma torus. X-ray imaging spectroscopy can be a new probe to reveal rotationally driven activities, particle acceleration and Jupiter–satellite binary system. JUXTA is composed of an ultra-light weight X-ray telescope based on micromachining technology and a radiation-hard semiconductor pixel detector. It covers 0.3–2 keV with the energy resolution of <100 eV at 0.6 keV. Because of proximity to Jupiter (∼30 Jovian radii at periapsis), the image resolution of <5 arcmin and the on-axis effective area of >3 cm2 at 0.6 keV allow extremely high photon statistics and high resolution observations. 相似文献
155.
M. Van Der Klis 《Space Science Reviews》1993,62(1-2):173-202
The observational information on X-ray binaries that was collected with the 80 cm2 auxiliary X-ray detector onboard the COS-B gamma-ray satellite is reviewed. The results illustrate that in the study of X-ray binaries observations of long duration are extremely effective, even when using a small instrument. 相似文献
156.
157.
David H. Rodgers Patricia M. Beauchamp Laurence A. Soderblom Robert H. Brown Gun-Shing Chen Meemong Lee Bill R. Sandel David A. Thomas Robert T. Benoit Roger V. Yelle 《Space Science Reviews》2007,129(4):309-326
MICAS is an integrated multi-channel instrument that includes an ultraviolet imaging spectrometer (80–185 nm), two high-resolution
visible imagers (10–20 μrad/pixel, 400–900 nm), and a short-wavelength infrared imaging spectrometer (1250–2600 nm). The wavelength ranges were chosen
to maximize the science data that could be collected using existing semiconductor technologies and avoiding the need for multi-octave
spectrometers. It was flown on DS1 to validate technologies derived from the development of PICS (Planetary Imaging Camera
Spectrometer). These technologies provided a novel systems approach enabling the miniaturization and integration of four instruments
into one entity, spanning a wavelength range from the UV to IR, and from ambient to cryogenic temperatures with optical performance
at a fraction of a wavelength. The specific technologies incorporated were: a built-in fly-by sequence; lightweight and ultra-stable,
monolithic silicon-carbide construction, which enabled room-temperature alignment for cryogenic (85–140 K) performance, and
provided superb optical performance and immunity to thermal distortion; diffraction-limited, shared optics operating from
80 to 2600 nm; advanced detector technologies for the UV, visible and short-wavelength IR; high-performance thermal radiators
coupled directly to the short-wave infrared (SWIR) detector optical bench, providing an instrument with a mass less than 10
kg, instrument power less than 10 W, and total instrument cost of less than ten million dollars. The design allows the wavelength
range to be extended by at least an octave at the short wavelength end and to ∼50 microns at the long wavelength end. Testing
of the completed instrument demonstrated excellent optical performance down to 77 K, which would enable a greatly reduced
background for longer wavelength detectors. During the Deep Space 1 Mission, MICAS successfully collected images and spectra
for asteroid 9969 Braille, Mars, and comet 19/P Borrelly. The Borrelly encounter was a scientific hallmark providing the first
clear, high resolution images and excellent, short-wavelength infrared spectra of the surface of an active comet’s nucleus. 相似文献
158.
本文将Bar-Kana等人的模型参考自适应控制法(MRAC)用于柔性结构的自适应控制中,原方法要求系统的输入维数等于输出维数。对于柔性的大型空间结构(LSS),观测量的数目往往大于输入量的数目。本文采用组合LSS各观测点的信号,形成综合输出矢量Y_P,以满足自适应控制系统中,用较少的控制输入达到控制LSS结构中较多观测点的要求。为了克服跟踪误差,本文建议用最优返馈增益阵作为输出阵C_P,并采用LQR理论以求C_P。 本文将大型空间结构的实例简化成离散模型,进行模拟计算,计算结果说明系统有较好的跟踪特性,当LSS的柔度变化较大时,系统具有跟踪的鲁棒性。 相似文献
159.
José F. Valdés-Galicia 《Space Science Reviews》1993,62(1-2):67-93
It is the purpose of this review to summarize and discuss recent research done in the field of particle propagation in the heliosphere. Several lines of approach have been followed to treat this problem. As a starting point the different forms of the transport equation are discussed. Quasi-Linear Theory (QLT) relates the power contained in fluctuations of the Interplanetary Magnetic Field (IMF) to the transport coefficients of energetic particles, an outline of the basic results of this theory is presented followed by a discussion of subsequent corrections made to the original formulation with an emphasis in recent developments where the effects of wave polarization, its propagation respect to the solar wind and the dissipation of power at large frequencies have been taken into account. The numerical approach using test particle trajectory integrations to obtain transport coefficients based on in situ satellite measureents is also discussed. It is well known that the determination of the particles mean free path for solar particle events by alternative methods leads to conflicting results, corrections made to original QLT are attempts to bridge the gap. Determination of the transport parameters from different lines of approach in a comparative basis have been done recently by calculating power spectra of IMF measured at the time solar particles were detected on the same spaceprobe, and performing numerical simulations with equivalent IMF data. Some of the results of such studies point to the solution of the conflicting determinations of the mean free path which has existed for nearly 30 years. An assesment of the present situation in this respect is given. Numerical determinations of transport parameters in the outer heliosphere are also reviewed and its consequences for solar modulation of galactic cosmic rays discussed. Space Science Reviews 62: Printed in Belgium. 相似文献
160.
Hideo Hanada Takahiro Iwata Qinghui Liu Fuyuhiko Kikuchi Koji Matsumoto Sander Goossens Yuji Harada Kazuyoshi Asari Toshiaki Ishikawa Yoshiaki Ishihara Hirotomo Noda Seiitsu Tsuruta Natalia Petrova Nobuyuki Kawano Sho Sasaki Kaori Sato Noriyuki Namiki Yusuke Kono Kenzaburo Iwadate Osamu Kameya Katsunori M. Shibata Yoshiaki Tamura Shunichi Kamata Yukihiro Yahagi Wataru Masui Koji Tanaka Hironori Maejima Xiaoyu Hong Jinsong Ping Xian Shi Qian Huang Yusufu Aili Simon Ellingsen Wolfgang Schlüter 《Space Science Reviews》2010,154(1-4):123-144
The Japanese lunar explorer SELENE (Kaguya), which was launched on September 14th, 2007, was the target of VLBI observations over the period November 2007 to June 2009. These observations were made in order to improve the lunar gravity field model, in particular the lower degree coefficients and the model near the limb. Differential VLBI Radio sources, called VRAD instruments, were on-board the subsatellites, Rstar (Okina) and Vstar (Ouna), and the radio signals were observed by the Japanese VERA (VLBI Exploration of Radio Astrometry) network, and an international VLBI network. Multi-frequency and same-beam VLBI techniques were utilized and were essential aspects of the successful observing program. Multi-frequency VLBI was employed in order to improve the accuracy of the orbit determination obtained from the phase delay from the narrow-band satellite signals, while the same-beam VLBI method was used to resolve the cycle ambiguity which is inherent in the multi-frequency VLBI method. The observations were made at three S-band frequencies (2212, 2218 and 2287 MHz), and one X-band frequency (8456 MHz). We have succeeded in correlating the recorded signals from Okina/Ouna, and we obtained phase delays with an accuracy of several pico-seconds at S-band. 相似文献