排序方式: 共有38条查询结果,搜索用时 15 毫秒
21.
Maria T. Zuber Oded Aharonson Jonathan M. Aurnou Andrew F. Cheng Steven A. Hauck II Moritz H. Heimpel Gregory A. Neumann Stanton J. Peale Roger J. Phillips David E. Smith Sean C. Solomon Sabine Stanley 《Space Science Reviews》2007,131(1-4):105-132
Current geophysical knowledge of the planet Mercury is based upon observations from ground-based astronomy and flybys of the
Mariner 10 spacecraft, along with theoretical and computational studies. Mercury has the highest uncompressed density of the
terrestrial planets and by implication has a metallic core with a radius approximately 75% of the planetary radius. Mercury’s
spin rate is stably locked at 1.5 times the orbital mean motion. Capture into this state is the natural result of tidal evolution
if this is the only dissipative process affecting the spin, but the capture probability is enhanced if Mercury’s core were
molten at the time of capture. The discovery of Mercury’s magnetic field by Mariner 10 suggests the possibility that the core
is partially molten to the present, a result that is surprising given the planet’s size and a surface crater density indicative
of early cessation of significant volcanic activity. A present-day liquid outer core within Mercury would require either a
core sulfur content of at least several weight percent or an unusual history of heat loss from the planet’s core and silicate
fraction. A crustal remanent contribution to Mercury’s observed magnetic field cannot be ruled out on the basis of current
knowledge. Measurements from the MESSENGER orbiter, in combination with continued ground-based observations, hold the promise
of setting on a firmer basis our understanding of the structure and evolution of Mercury’s interior and the relationship of
that evolution to the planet’s geological history. 相似文献
22.
Suess S. T. Phillips J. L. McComas D. J. Goldstein B. E. Neugebauer M. Nerney S. 《Space Science Reviews》1998,83(1-2):75-86
The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses. 相似文献
23.
D. A. Gurnett A. M. Persoon R. F. Randall D. L. Odem S. L. Remington T. F. Averkamp M. M. Debower G. B. Hospodarsky R. L. Huff D. L. Kirchner M. A. Mitchell B. T. Pham J. R. Phillips W. J. Schintler P. Sheyko D. R. Tomash 《Space Science Reviews》1995,71(1-4):597-622
The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop antenna and a triaxial magnetic search coil antenna are used to detect magnetic fields. Signals from these antennas are processed by five receiver systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pair of sweep frequency receivers. Compared to previous plasma wave instruments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simultaneously capture signals from six orthogonal electric and magnetic field sensors, and (3) a digital wideband receiver with up to 8-bit resolution and sample rates as high as 249k samples s–1. 相似文献
24.
J. T. Gosling S. J. Bame D. J. Mccomas J. L. Phillips A. Balogh K. T. Strong 《Space Science Reviews》1995,72(1-2):133-136
Nine coronal mass ejections (CMEs) have been detected in the solar wind by the Ulysses plasma experiment between 31° and 61° South. One of these events, which was also a magnetic cloud, was directly associated with an event observed by the soft X-ray telescope on Yohkoh in which large magnetic loops formed in the solar corona directly beneath Ulysses. This association suggests that the flux rope topology of the magnetic cloud resulted from reconnection between the legs of neighboring magnetic loops within the rising CME. The average CME speed (740 km s–1) at these latitudes was comparable to that of the normal solar wind there and is much greater than average CME speeds observed either in the solar wind in the ecliptic plane or in the corona close to the Sun. We suggest that the same basic acceleration process applies to both slow CMEs and the normal solar wind at any latitude. 相似文献
25.
L. Fletcher B. R. Dennis H. S. Hudson S. Krucker K. Phillips A. Veronig M. Battaglia L. Bone A. Caspi Q. Chen P. Gallagher P. T. Grigis H. Ji W. Liu R. O. Milligan M. Temmer 《Space Science Reviews》2011,159(1-4):19-106
We present an overview of solar flares and associated phenomena, drawing upon a wide range of observational data primarily from the RHESSI era. Following an introductory discussion and overview of the status of observational capabilities, the article is split into topical sections which deal with different areas of flare phenomena (footpoints and ribbons, coronal sources, relationship to coronal mass ejections) and their interconnections. We also discuss flare soft X-ray spectroscopy and the energetics of the process. The emphasis is to describe the observations from multiple points of view, while bearing in mind the models that link them to each other and to theory. The present theoretical and observational understanding of solar flares is far from complete, so we conclude with a brief discussion of models, and a list of missing but important observations. 相似文献
26.
The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP 总被引:2,自引:0,他引:2
C. A. Kletzing W. S. Kurth M. Acuna R. J. MacDowall R. B. Torbert T. Averkamp D. Bodet S. R. Bounds M. Chutter J. Connerney D. Crawford J. S. Dolan R. Dvorsky G. B. Hospodarsky J. Howard V. Jordanova R. A. Johnson D. L. Kirchner B. Mokrzycki G. Needell J. Odom D. Mark R. Pfaff Jr. J. R. Phillips C. W. Piker S. L. Remington D. Rowland O. Santolik R. Schnurr D. Sheppard C. W. Smith R. M. Thorne J. Tyler 《Space Science Reviews》2013,179(1-4):127-181
The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation Belt Storm Probes (now named the Van Allen Probes) mission provides key wave and very low frequency magnetic field measurements to understand radiation belt acceleration, loss, and transport. The key science objectives and the contribution that EMFISIS makes to providing measurements as well as theory and modeling are described. The key components of the instruments suite, both electronics and sensors, including key functional parameters, calibration, and performance, demonstrate that EMFISIS provides the needed measurements for the science of the RBSP mission. The EMFISIS operational modes and data products, along with online availability and data tools provide the radiation belt science community with one the most complete sets of data ever collected. 相似文献
27.
A. H. Manson C. E. Meek M. Massebeuf J. L. Fellous W. G. Elford R. A. Vincent R. L. Craig A. Phillips R. G. Roper G. J. Fraser M. J. Smith S. Avery B. B. Balsley R. R. Clark S. Kato T.Tsuda R. Schminder D. Kuerschner 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1990,10(12):267-315
28.
B. E. Goldstein M. Neugebauer J. T. Gosling S. J. Bame J. L. Phillips D. J. Mccomas A. Balogh 《Space Science Reviews》1995,72(1-2):113-116
We report observations of radial and latitudinal gradients of Ulysses plasma parameters. The solar wind velocity increased rapidly with latitude from 0° to 35°, then remained approximately constant at higher latitudes. Solar wind density decreased rapidly from 0° to 35° of latitude, and also was approximately constant beyond that latitude. The mass flux similarly decreased away from the equator (but less than the density), whereas the momentum flux was relatively constant. The radial gradient of the entropy at high latitude indicated a value for the polytrope index of about 1.72 (close to adiabatic); the in-ecliptic estimates of radial gradients for temperature and entropy may be biased by temporal variation. A striking increase in the alpha particle-proton velocity difference with latitude is found. 相似文献
29.
Earl E. Scime Samuel J. Bame John L. Phillips Andre Balogh 《Space Science Reviews》1995,72(1-2):105-108
Ulysses measurements of the solar wind electron heat flux as a function of heliographic latitude are presented. The latitudinal in the electron heat flux presented have been normalized by the radial gradient in the electron heat flux obtained during the in-ecliptic phase of the Ulysses mission (qe R–3.0). We find no significant variation in electron heat flux with latitude. 相似文献
30.
J.G. Luhmann J.L. Phillips C.T. Russell 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(12):101-106
The dayside ionospheric magnetic field of Venus has been modelled from two different points of view. The Cloutier et al. electrodynamic model makes specific predictions about the behavior of the global magnetic field configuration that can be compared with those expected from the alternate diffusion/convection model. Although the diffusion/convection model is currently only one-dimensional, it is found that it is consistent with the observations in several areas where the 3-dimensional electrodynamic model is not. 相似文献