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11.
Kobayashi Masanori Shibata Hiromi Nogami Ken’ichi Fujii Masayuki Hasegawa Sunao Hirabayashi Masatoshi Hirai Takayuki Iwai Takeo Kimura Hiroshi Miyachi Takashi Nakamura Maki Ohashi Hideo Sasaki Sho Takechi Seiji Yano Hajime Krüger Harald Lohse Ann-Kathrin Srama Ralf Strub Peter Grün Eberhard 《Space Science Reviews》2020,216(8):1-49
Space Science Reviews - In this chapter, we review the contribution of space missions to the determination of the elemental and isotopic composition of Earth, Moon and the terrestrial planets, with... 相似文献
12.
Rumi Nakamura 《Space Science Reviews》2006,124(1-4):91-101
Consequences of the solar wind input observed as large scale magnetotail dynamics during substorms are reviewed, highlighting
results from statistical studies as well as global magnetosphere/ionosphere observations. Among the different solar wind input
parameters, the most essential one to initiate reconnection relatively close to the Earth is a southward IMF or a solar wind
dawn-to-dusk electric field. Larger substorms are associated with such reconnection events closer to the Earth and the magnetotail
can accumulate larger amounts of energy before its onset. Yet, how and to what extent the magnetotail configuration before
substorm onset differs for different solar wind driver is still to be understood. A strong solar wind dawn-to-dusk electric
field is, however, only a necessary condition for a strong substorm, but not a sufficient one. That is, there are intervals
when the solar wind input is processed in the magnetotail without the usual substorm cycle, suggesting different modes of
flux transport. Furthermore, recent global observations suggest that the magnetotail response during the substorm expansion
phase can be also controlled by plasma sheet density, which is coupled to the solar wind on larger time-scales than the substorm
cycle. To explain the substorm dynamics it is therefore important to understand the different modes of energy, momentum, and
mass transport within the magnetosphere as a consequence of different types of solar wind-magnetosphere interaction with different
time-scales that control the overall magnetotail configuration, in addition to the internal current sheet instabilities leading
to large scale tail current sheet dissipation. 相似文献
13.
The dynamics of the current sheet is one of the most essential elements in magnetotail physics. Particularly, thin current
sheets, which we define here as those with a thickness of less than several ion inertia lengths, are known to play an important
role in the energy conversion process in the magnetotail. With its capability of multi-point observation, Cluster succeeded
to obtain the current density continuously and therefore identify structures of thin current sheets. We discuss characteristics
of the thin current sheets by showing their temporal evolution and the spatial structures based on several Cluster observations. 相似文献
14.
During the last several years significant progress has been made in understanding MHD turbulence in the Earth’s plasma sheet.
Due to the statistically transitory properties of fluctuations, finite size and boundary effects, however, issues of fundamental
importance remain unresolved. Here we concentrate on such intrinsic features of plasma sheet turbulence as its origin and
dynamical nature. In particular, we investigate bursty bulk flow driven multi-scale transfer of energy towards the dissipation
scale, and provide evidence for the presence of non-linear interactions. We show that, in contrast with previous results,
Alfvénic fluctuations together with 2D eddy interactions may appear as important constituents of turbulence in the plasma
sheet. 相似文献
15.
S. V. Apatenkov T. M. Sugak V. A. Sergeev M. A. Shukhtina R. Nakamura W. Baumjohann P. Daly 《Cosmic Research》2009,47(1):22-28
Injections of energetic electrons with a dispersion over energies were observed during the February 23, 2004 (at about 03:20 UT) substorm onboard the Cluster satellites in the vicinity of perigee near the midnight meridian. The delays in the particle observation caused by the energy dependence of the magnetic drift velocities made it possible to determine the position and time of the beginning of the drift, tracing the trajectories of the leading center of particles back in time in the magnetospheric model. The comparisons of the measurements of four satellites allowed us to determine the radial propagation of the injection front with a velocity of 100–150 km/s at a distance of 7–9 R E. The comparison with a few previous measurements shows a substantial slowing down of injections as they approached the Earth, and this confirms the prospects of this method for more detailed study of propagation of plasma injection into the inner magnetosphere. 相似文献
16.
Mono Shimizu Katsuya Itoh Hitoshi SatoTadayuki FujiiKen-ichi Okamoto Shigehiko TakaokaKotaro ShiinaYoshihiro Nakamura 《Acta Astronautica》1999,44(7-12):345-351
One potentially attractive propulsion concept offering significant payload gains for orbit transfer from LEO to higher orbits, station keeping and attitude control of spacecraft is thermal propulsion using light gas (typically hydrogen) as propellant and various kinds of heat energy. Solar Thermal Propulsion (STP) is a typical thermal propulsion with high Isp (500 – 1,000 s) in an appropriate thrust magnitude range and provides possibly much less space pollution than conventional chemical propulsion.
This paper presents the test results of a 30 mm dia. (medium-sized) windowless type of single crystal Mo thruster for orbit transfer of 50 kg class microsatellites. The cavity dia. is 20 mm, double the size of the previous model, and can apply to a primary solar reflector of up to 3.5 m dia., which is the maximum size containable in the H-II rocket fairing without segmentation. The performed mission analyses indicate that this size of STP is suitable to orbit transfer of 50 kg class microsatellites, such as LEO to GEO, or only multiple apogee kicks from GTO to GEO or deep space missions. 相似文献
17.
The THEMIS Fluxgate Magnetometer 总被引:2,自引:0,他引:2
H. U. Auster K. H. Glassmeier W. Magnes O. Aydogar W. Baumjohann D. Constantinescu D. Fischer K. H. Fornacon E. Georgescu P. Harvey O. Hillenmaier R. Kroth M. Ludlam Y. Narita R. Nakamura K. Okrafka F. Plaschke I. Richter H. Schwarzl B. Stoll A. Valavanoglou M. Wiedemann 《Space Science Reviews》2008,141(1-4):235-264
18.
Masanori Matsushita Toshihiro Chujo Jun Matsumoto Osamu Mori Rikio Yokota Hiroyuki Toyota Yasutaka Satou Nobukatsu Okuizumi Hideki Kato Tetsuya Nakamura Yuichi Shibata Tatsuro Nakao Kazuyuki Mori Sanae Fujii Yuki Takao Yuki Kubo Yuya Miyamoto Yuichiro Nada Yudai Kimishima 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(9):2899-2911
This paper reports on the manufacturing and evaluation of a solar power sail membrane prototype for the OKEANOS project. The in-house prototype was built by the Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency. Mechanical and electrical evaluation tests were conducted. The membrane, thin-film solar cells, reflectivity control devices were good condition after the manufacturing and handling. The improvements in the manufacturing process and design were found. The manufacturing process and design were fundamentally established. After the prototype, improvement plans for the manufacturing process and design were tried. We have a prospect of manufacturing the flight model sail and continue to the development. 相似文献
19.
Yuko Ishizaki Hideoki Fukuoka Hidetaka Tanaka Tatsuro Ishizaki Yuri Fujii Yuko Hattori-Uchida Minako Nakamura Kaoru Ohkawa Hodaka Kobayashi Shoichiro Taniuchi Kazunari Kaneko 《Acta Astronautica》2009,64(9-10):864-868
Microgravity due to prolonged bed rest may cause changes in cerebral circulation, which is related to brain function. We evaluate the effect of simulated microgravity due to a 6° head-down tilt bed rest experiment on executive function among 12 healthy young men. Four kinds of psychoneurological tests—the table tapping test, the trail making test, the pointing test and losing at rock–paper–scissors—were performed on the baseline and on day 16 of the experiment. There was no significant difference in the results between the baseline and day 16 on all tests, which indicated that executive function was not impaired by the 16-day 6° head-down tilting bed rest. However, we cannot conclude that microgravity did not affect executive function because of the possible contribution of the following factors: (1) the timing of tests, (2) the learning effect, or (3) changes in psychophysiology that were too small to affect higher brain function. 相似文献
20.
T. Sato K. Niita V. A. Shurshakov E. N. Yarmanova I. V. Nikolaev H. Iwase L. Sihver D. Mancusi A. Endo N. Matsuda Y. Iwamoto H. Nakashima Y. Sakamoto H. Yasuda M. Takada T. Nakamura 《Cosmic Research》2011,49(4):319-324
The dose reduction rates brought about by the installation of additional water shielding in a spacecraft are calculated in the paper using the particles and heavy ion transport code system PHITS, which can deal with transport of all kinds of hadrons and heavy ions with energies up to 100 GeV/n in three-dimensional phase spaces. In the PHITS simulation, an imaginary spacecraft was irradiated isotropically by cosmic rays with charges up to 28 and energies up to 100 GeV/n, and the dose reduction rates due to water shielding were evaluated for 5 types of doses: the dose equivalents obtained from the LET and linear energy spectra, the dose equivalents to skin and red bone marrow, and the effective dose equivalent. The results of the simulation indicate that the dose reduction rates differ according to the type of dose evaluated. For example, 5 g/cm2 water shielding reduces the effective dose equivalent and the LET dose equivalent by approximately 14% and 32%, respectively. Such degrees of dose reduction can be regarded to make water shielding worth the efforts required to install it. 相似文献