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291.
Yoon Kyung Seo Dong Young Rew Georg Kirchner Eunseo Park Mansoo Choi Sung Yeol Yu Jiwoong Heo Cheong Youn 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
For the development of a telescope that is capable of precisely tracking satellites and high-speed operation such as satellite laser ranging, a special method of telescope operation is required. This study aims to propose a new telescope operation method and system configuration for the independent development of a mount and an operation system which includes the host computer. Considering that the tracking of a satellite is performed in real time, communication and synchronization between the two independent subsystems are important. Therefore, this study applied the concept of time synchronization, which is used in various fields of industry, to the communication between the command computer and the mount. In this case, communication delays do not need to be considered in general, and it is possible to cope with data loss. Above all, when the mount is replaced in the future, only the general communication interface needs to be modified, and thus, it is not limited by replacement in terms of the overall system management. The performance of the telescope operation method developed in this study was verified by applying the method to the first mobile SLR system in Korea. This study is significant in that it proposed a new operation method and system configuration, to which the concept of time synchronization was applied, for the observation system that requires an optical telescope. 相似文献
292.
The Jupiter Energetic Particle Detector Instrument (JEDI) Investigation for the Juno Mission 总被引:1,自引:0,他引:1
B. H. Mauk D. K. Haggerty S. E. Jaskulek C. E. Schlemm L. E. Brown S. A. Cooper R. S. Gurnee C. M. Hammock J. R. Hayes G. C. Ho J. C. Hutcheson A. D. Jacques S. Kerem C. K. Kim D. G. Mitchell K. S. Nelson C. P. Paranicas N. Paschalidis E. Rossano M. R. Stokes 《Space Science Reviews》2017,213(1-4):289-346
The Jupiter Energetic Particle Detector Instruments (JEDI) on the Juno Jupiter polar-orbiting, atmosphere-skimming, mission to Jupiter will coordinate with the several other space physics instruments on the Juno spacecraft to characterize and understand the space environment of Jupiter’s polar regions, and specifically to understand the generation of Jupiter’s powerful aurora. JEDI comprises 3 nearly-identical instruments and measures at minimum the energy, angle, and ion composition distributions of ions with energies from H:20 keV and O: 50 keV to >1 MeV, and the energy and angle distribution of electrons from <40 to >500 keV. Each JEDI instrument uses microchannel plates (MCP) and thin foils to measure the times of flight (TOF) of incoming ions and the pulse height associated with the interaction of ions with the foils, and it uses solid state detectors (SSD’s) to measure the total energy (E) of both the ions and the electrons. The MCP anodes and the SSD arrays are configured to determine the directions of arrivals of the incoming charged particles. The instruments also use fast triple coincidence and optimum shielding to suppress penetrating background radiation and incoming UV foreground. Here we describe the science objectives of JEDI, the science and measurement requirements, the challenges that the JEDI team had in meeting these requirements, the design and operation of the JEDI instruments, their calibrated performances, the JEDI inflight and ground operations, and the initial measurements of the JEDI instruments in interplanetary space following the Juno launch on 5 August 2011. Juno will begin its prime science operations, comprising 32 orbits with dimensions 1.1×40 RJ, in mid-2016. 相似文献
293.
T. M. Ho N. Thomas D. C. Boice C. Kollein L. A. Soderblom 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(12):2583-2589
Images obtained by the Miniature Integrated Camera and Imaging Spectrometer (MICAS) experiment onboard the Deep Space 1 spacecraft which encountered comet 19P/Borrelly on September 22nd 2001 show a dust coma dominated by jets. In particular a major collimated dust jet on the sunward side of the nucleus was observed. Our approach to analyse these features is to integrate the observed intensity in concentric envelopes around the nucleus. The same procedures has been used on the Halley Multicolour Camera images of comet 1P/Halley acquired on March 14th 1986. We are able to show that at Borrelly the dust brightness dependence as a function of radial distance is different to that of Halley. At large distances both comets show constant values as the size of the concentric envelopes increases (as one would expect for force free radial outflow). For Halley the integral decreases as one gets closer to the nucleus. Borrelly shows opposite behaviour. The main cause for Halley's intensity distribution is either high optical thickness or particle fragmentation. For Borrelly, we have constructed a simple model of the brightness distribution near the nucleus. This indicates that the influence of deviations from point source geometry is insufficient to explain the observed steepening of the intensity profile close to the nucleus. Dust acceleration or fragmentation into submicron particles appear to be required. We also estimate the dust production rate of Borrelly with respect to Halley and compare their dust to gas ratios. 相似文献
294.
The Upgraded CARISMA Magnetometer Array in the THEMIS Era 总被引:1,自引:0,他引:1
I. R. Mann D. K. Milling I. J. Rae L. G. Ozeke A. Kale Z. C. Kale K. R. Murphy A. Parent M. Usanova D. M. Pahud E.-A. Lee V. Amalraj D. D. Wallis V. Angelopoulos K.-H. Glassmeier C. T. Russell H.-U. Auster H. J. Singer 《Space Science Reviews》2008,141(1-4):413-451
This review describes the infrastructure and capabilities of the expanded and upgraded Canadian Array for Realtime InvestigationS of Magnetic Activity (CARISMA) magnetometer array in the era of the THEMIS mission. Formerly operated as the Canadian Auroral Network for the OPEN Program Unified Study (CANOPUS) magnetometer array until 2003, CARISMA capabilities have been extended with the deployment of additional fluxgate magnetometer stations (to a total of 28), the upgrading of the fluxgate magnetometer cadence to a standard data product of 1 sample/s (raw sampled 8 samples/s data stream available on request), and the deployment of a new network of 8 pairs of induction coils (100 samples per second). CARISMA data, GPS-timed and backed up at remote field stations, is collected using Very Small Aperture Terminal (VSAT) satellite internet in real-time providing a real-time monitor for magnetic activity on a continent-wide scale. Operating under the magnetic footprint of the THEMIS probes, data from 5 CARISMA stations at 29–30 samples/s also forms part of the formal THEMIS ground-based observatory (GBO) data-stream. In addition to technical details, in this review we also outline some of the scientific capabilities of the CARISMA array for addressing all three of the scientific objectives of the THEMIS mission, namely: 1. Onset and evolution of the macroscale substorm instability, 2. Production of storm-time MeV electrons, and 3. Control of the solar wind-magnetosphere coupling by the bow shock, magnetosheath, and magnetopause. We further discuss some of the compelling questions related to these three THEMIS mission science objectives which can be addressed with CARISMA. 相似文献
295.
Kyeong Ja Kim Joo-Hee Lee Haingja Seo Gwanghyeok Ju Sang-Ryool Lee Gi-Hyuk Choi Eun-Sup Sim Tai Sik Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Korea is planning a series of lunar space programs in 2020 starting with a lunar orbiter and a lander with a rover. Compared to other countries, Korea has a relatively brief history in space and planetary sciences. With the expected Korean missions on the near-term horizon and the relatively few Korean planetary scientists, Korea Institute of Geoscience and Mineral Resources (KIGAM) has established a new planetary research group focusing on development of prospective lunar instruments, analysis of the publicly available planetary data of the Moon, organizing nationwide planetary workshops, and initiating planetary educational programs with academic institutions. Korea has also initiated its own rocket development program, which could acquire a rocket-launch capability toward the Korean lunar mission. For the prospective Korea’s lunar science program, feasibility studies for some candidate science payloads have been started since 2010 for an orbiter and a lander. The concept design of each candidate instrument has been accomplished in 2012. It is expected that the development of science payloads may start by 2014 as Phase A. Not only developing hardware required for the lunar mission but also educational activities for young students are high priorities for Korea. The new plan of the Korean lunar mission can be successfully accomplished with international cooperative outreach programs in conjunction with internationally accessible planetary data system (PDS). This paper introduces the KIGAM’s international cooperative planetary research and educational programs and also summarizes other nationwide new developments for Korean lunar research projects at Kyung Hee University and Hanyang University. 相似文献
296.
提出根据载客量、航程、巡航速度和高度即可初步确定斜置飞翼超声速旅客机气动外形参数的方法.讨论了对称面弦长的选取范围,确定了展弦比、起飞翼载荷与展长的关系,提出了展弦比、起飞翼载荷的选取原则,并推导了油箱展向长度和客舱展向长度迭代公式.为了研究技术要求对斜置飞翼超声速旅客机气动外形参数的影响,对载客量250~550、航程6500~10000 km、升阻比11~12内若干设计点进行了研究分析.结果表明,所设计的飞翼存在一起飞重量阈值,当起飞重量小于该阈值时机翼面积由展弦比下限确定,当起飞重量大于此阈值时机翼面积由起飞翼载荷上限确定;提高巡航升阻比可减小由起飞翼载荷上限确定的机翼面积. 相似文献
297.
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
298.
C. Carr E. Cupido C. G. Y. Lee A. Balogh T. Beek J. L. Burch C. N. Dunford A. I. Eriksson R. Gill K. H. Glassmeier R. Goldstein D. Lagoutte R. Lundin K. Lundin B. Lybekk J. L. Michau G. Musmann H. Nilsson C. Pollock I. Richter J. G. Trotignon 《Space Science Reviews》2007,128(1-4):629-647
The Rosetta Plasma Consortium (RPC) will make in-situ measurements of the plasma environment of comet 67P/Churyumov-Gerasimenko.
The consortium will provide the complementary data sets necessary for an understanding of the plasma processes in the inner
coma, and the structure and evolution of the coma with the increasing cometary activity. Five sensors have been selected to
achieve this: the Ion and Electron Sensor (IES), the Ion Composition Analyser (ICA), the Langmuir Probe (LAP), the Mutual
Impedance Probe (MIP) and the Magnetometer (MAG). The sensors interface to the spacecraft through the Plasma Interface Unit
(PIU). The consortium approach allows for scientific, technical and operational coordination, and makes optimum use of the
available mass and power resources. 相似文献
299.
Micro-Doppler effect in radar: phenomenon, model, and simulation study 总被引:51,自引:0,他引:51
Chen V.C. Li F. Ho S.-S. Wechsler H. 《IEEE transactions on aerospace and electronic systems》2006,42(1):2-21
When, in addition to the constant Doppler frequency shift induced by the bulk motion of a radar target, the target or any structure on the target undergoes micro-motion dynamics, such as mechanical vibrations or rotations, the micro-motion dynamics induce Doppler modulations on the returned signal, referred to as the micro-Doppler effect. We introduce the micro-Doppler phenomenon in radar, develop a model of Doppler modulations, derive formulas of micro-Doppler induced by targets with vibration, rotation, tumbling and coning motions, and verify them by simulation studies, analyze time-varying micro-Doppler features using high-resolution time-frequency transforms, and demonstrate the micro-Doppler effect observed in real radar data. 相似文献
300.