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排序方式: 共有294条查询结果,搜索用时 281 毫秒
121.
G. Randall Gladstone Steven C. Persyn John S. Eterno Brandon C. Walther David C. Slater Michael W. Davis Maarten H. Versteeg Kristian B. Persson Michael K. Young Gregory J. Dirks Anthony O. Sawka Jessica Tumlinson Henry Sykes John Beshears Cherie L. Rhoad James P. Cravens Gregory S. Winters Robert A. Klar Walter Lockhart Benjamin M. Piepgrass Thomas K. Greathouse Bradley J. Trantham Philip M. Wilcox Matthew W. Jackson Oswald H. W. Siegmund John V. Vallerga Rick Raffanti Adrian Martin J.-C. Gérard Denis C. Grodent Bertrand Bonfond Benoit Marquet François Denis 《Space Science Reviews》2017,213(1-4):447-473
The ultraviolet spectrograph instrument on the Juno mission (Juno-UVS) is a long-slit imaging spectrograph designed to observe and characterize Jupiter’s far-ultraviolet (FUV) auroral emissions. These observations will be coordinated and correlated with those from Juno’s other remote sensing instruments and used to place in situ measurements made by Juno’s particles and fields instruments into a global context, relating the local data with events occurring in more distant regions of Jupiter’s magnetosphere. Juno-UVS is based on a series of imaging FUV spectrographs currently in flight—the two Alice instruments on the Rosetta and New Horizons missions, and the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter mission. However, Juno-UVS has several important modifications, including (1) a scan mirror (for targeting specific auroral features), (2) extensive shielding (for mitigation of electronics and data quality degradation by energetic particles), and (3) a cross delay line microchannel plate detector (for both faster photon counting and improved spatial resolution). This paper describes the science objectives, design, and initial performance of the Juno-UVS. 相似文献
122.
Jianguo Yan Zhen Zhong Fei Li James M. Dohm Jinsong Ping Jianfeng Cao Xie Li 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We analyzed the 150 × 150 lunar gravity field models, LP150Q, GLGM-3 and SGM150, using the power spectrum on the lunar nearside and farside, the lunar global and localized gravity/topography admittance and correlation, and Chang’E-2 precision orbit determination to investigate which model is a more effective tool to estimate geophysical parameters and determine the lunar satellite precision orbit. Results indicate that all gravity field models can be used to estimate the lunar geophysical parameters of the nearside of the Moon. However, SGM150 is better in such computation of the farside. Additionally, SGM150 is shown to be the most useful model for determining the lunar satellite orbit. 相似文献
123.
The “classic” anomalous cosmic ray (ACR) component originates as interstellar neutral atoms that drift into the heliosphere, become ionized and picked up by the solar wind, and carried to the outer heliosphere where the pickup ions are accelerated to hundreds of MeV, presumably at the solar wind termination shock. These interstellar ACRs are predominantly singly charged, although higher charge states are present and become dominant above ~350 MeV. Their isotopic composition is like that of the solar system and unlike that of the source of galactic cosmic rays. A comparison of their energy spectra with the estimated flux of pickup ions flowing into the termination shock reveals a mass-dependent acceleration efficiency that favors heavier ions. There is also a heliospheric ACR component as evidenced by “minor” ACR ions, such as Na, Mg, S, and Si that appear to be singly-ionized ions from a source likely in the outer heliosphere. 相似文献
124.
Committee on Space Policy H.Guyford Stever Laurence J. Adams Consultant Retired President William A. Anders Senior Executive Vice President Arden L. Bement Jr Vice President Joseph V. Charyk Chairman of the Board Retired Chairman CEO Richard N. Cooper Robert S. Cooper President Edward E. David Jr President John M. Logsdon Director Jeremiah P. Ostriker Director Samuel C. Phillips Retired General Elmer B. Staats Edward C. Stone Jr Vice President 《Space Policy》1989,5(3)
125.
A proposal for an international satellite monitoring agency (ISMA) to verify arms control agreements was first made by France in 1978, and has been received enthusiastically, although not by the superpowers. The technologies available for verification are proliferating, and many countries feel they can make a useful contribution. The authors examine the impact an ISMA would actually have on international security and arms control, and propose several alternative avenues for international participation in verification. 相似文献
126.
We use energy spectra of anomalous cosmic rays (ACRs) measured with the Cosmic Ray instrument on the Voyager 1 and 2 spacecraft during the period 1994/157-313 to determine several parameters of interest to heliospheric studies. We estimate that the strength of the solar wind termination shock is 2.42 (–0.08, +0.04). We determine the composition of ACRs by estimating their differential energy spectra at the shock and find the following abundance ratios: H/He = 5.6 (–0.5, +0.6), C/He = 0.00048 ± 0.00011, N/He = 0.011 ± 0.001, O/He = 0.075 ± 0.006, and Ne/He = 0.0050 ± 0.0004. We correlate our observations with those of pickup ions to deduce that the long-term ionization rate of neutral nitrogen at 1 AU is 8.3 × 10–7 s–1 and that the charge-exchange cross section for neutral N and solar wind protons is 1.0 × 10–15 cm2 at 1.1 keV. We estimate that the neutral C/He ratio in the outer heliosphere is 1.8(–0.7, +0.9) × 10–5. We also find that heavy ions are preferentially injected into the acceleration process at the termination shock. 相似文献
127.
Gordon Chin Scott Brylow Marc Foote James Garvin Justin Kasper John Keller Maxim Litvak Igor Mitrofanov David Paige Keith Raney Mark Robinson Anton Sanin David Smith Harlan Spence Paul Spudis S. Alan Stern Maria Zuber 《Space Science Reviews》2007,129(4):391-419
NASA’s Lunar Precursor Robotic Program (LPRP), formulated in response to the President’s Vision for Space Exploration, will
execute a series of robotic missions that will pave the way for eventual permanent human presence on the Moon. The Lunar Reconnaissance
Orbiter (LRO) is first in this series of LPRP missions, and plans to launch in October of 2008 for at least one year of operation.
LRO will employ six individual instruments to produce accurate maps and high-resolution images of future landing sites, to
assess potential lunar resources, and to characterize the radiation environment. LRO will also test the feasibility of one
advanced technology demonstration package. The LRO payload includes: Lunar Orbiter Laser Altimeter (LOLA) which will determine
the global topography of the lunar surface at high resolution, measure landing site slopes, surface roughness, and search
for possible polar surface ice in shadowed regions, Lunar Reconnaissance Orbiter Camera (LROC) which will acquire targeted
narrow angle images of the lunar surface capable of resolving meter-scale features to support landing site selection, as well
as wide-angle images to characterize polar illumination conditions and to identify potential resources, Lunar Exploration
Neutron Detector (LEND) which will map the flux of neutrons from the lunar surface to search for evidence of water ice, and
will provide space radiation environment measurements that may be useful for future human exploration, Diviner Lunar Radiometer
Experiment (DLRE) which will chart the temperature of the entire lunar surface at approximately 300 meter horizontal resolution
to identify cold-traps and potential ice deposits, Lyman-Alpha Mapping Project (LAMP) which will map the entire lunar surface
in the far ultraviolet. LAMP will search for surface ice and frost in the polar regions and provide images of permanently
shadowed regions illuminated only by starlight. Cosmic Ray Telescope for the Effects of Radiation (CRaTER), which will investigate
the effect of galactic cosmic rays on tissue-equivalent plastics as a constraint on models of biological response to background
space radiation. The technology demonstration is an advanced radar (mini-RF) that will demonstrate X- and S-band radar imaging
and interferometry using light weight synthetic aperture radar. This paper will give an introduction to each of these instruments
and an overview of their objectives. 相似文献
128.
Donald L. Hampton James W. Baer Martin A. Huisjen Chris C. Varner Alan Delamere Dennis D. Wellnitz Michael F. A’Hearn Kenneth P. Klaasen 《Space Science Reviews》2005,117(1-2):43-93
A suite of three optical instruments has been developed to observe Comet 9P/Tempel 1, the impact of a dedicated impactor spacecraft,
and the resulting crater formation for the Deep Impact mission. The high-resolution instrument (HRI) consists of an f/35 telescope with 10.5 m focal length, and a combined filtered CCD camera and IR spectrometer. The medium-resolution instrument
(MRI) consists of an f/17.5 telescope with a 2.1 m focal length feeding a filtered CCD camera. The HRI and MRI are mounted on an instrument platform
on the flyby spacecraft, along with the spacecraft star trackers and inertial reference unit. The third instrument is a simple
unfiltered CCD camera with the same telescope as MRI, mounted within the impactor spacecraft. All three instruments use a
Fairchild split-frame-transfer CCD with 1,024× 1,024 active pixels. The IR spectrometer is a two-prism (CaF2 and ZnSe) imaging spectrometer imaged on a Rockwell HAWAII-1R HgCdTe MWIR array. The CCDs and IR FPA are read out and digitized
to 14 bits by a set of dedicated instrument electronics, one set per instrument. Each electronics box is controlled by a radiation-hard
TSC695F microprocessor. Software running on the microprocessor executes imaging commands from a sequence engine on the spacecraft.
Commands and telemetry are transmitted via a MIL-STD-1553 interface, while image data are transmitted to the spacecraft via a low-voltage differential signaling (LVDS) interface standard. The instruments are used as the science instruments and are
used for the optical navigation of both spacecraft. This paper presents an overview of the instrument suite designs, functionality,
calibration and operational considerations. 相似文献
129.
The performance of discriminator detection of wide-band PCM/FM is investigated. Formulas are derived that allow one to predict system performance with the effects of both predetection and postdetection filtering accounted for. In particular, for a postdetection equivalent noise bandwidthbit time product b0T=2, it is shown that best results are obtained with a modulation index ?=0.6. Furthermore, it is shown that performance to within 1.5 dB of theoretical can be obtained. 相似文献
130.
de Jager C. Hartle James B. Drawin H. W. Giovanelli R. G. Freudenthal Hans Wittenberg H. Tobias Cornelius A. Van Der Laan H. Smit J. A. 《Space Science Reviews》1974,15(5):741-746
Space Science Reviews - 相似文献