排序方式: 共有195条查询结果,搜索用时 984 毫秒
71.
H. Nieuwenhuijzen F. P. Israel C. Slottje L. B. F. M. Waters J. Kleczek K. Werner M. Barylak Patricia Whitelock Ľ Kresák G. Meynet K. A. van der Hucht D. Stickland 《Space Science Reviews》1992,61(3-4):393-417
The general significance of streamers of the solar corona is discussed in the frame of our knowledge of the solar wind phenomenon and the large-scale solar magnetic structure. Thermodynamical and geometric parameters of streamers observed and measured at total solar eclipses are reviewed. Both the low part (in the form of a helmet with a cusp) and the external part (in the form of a stalk extended at many solar radii) are considered. The modelling of streamers starts with the analysis of effects produced by the solar wind flow on a magnetic structure. Facts and arguments are presented in favor of a model with a current sheet and reconnection processes going on along the axis of the streamer, especially in the non-collisional part of the radially extended streamer. Further development of the Pneuman and Kopp (1971) model is discussed, including difficulties occurring in the interpretation of a stationary solution. An empirical model satisfying observations is presented. Future researchs on streamers were discussed with emphasis on observations to be done with the space-borne coronagraphs on the SOHO spacecraft. 相似文献
72.
We report on our recent progress in modeling non-LTE atmospheres of O-stars including blanketing by lines from the iron group elements. The numerical method to account for the huge number of atomic levels and line transitions is presented. Results of exploratory model calculations examining the effects on the temperature structure, the hydrogen and helium line profiles and UV/EUV fluxes are discussed. 相似文献
73.
74.
M. A. Barstow F. Wesemael J. B. Holberg K. Werner D. A. H. Buckley R. S. Stobie G. Fontaine S. R. Rosen S. Demers R. Lamontagne M. J. Irwin P. Bergeron S. O. Kepler S. Vennes 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1993,13(12):281-285
We report the discovery of two hot white dwarfs which have the lowest line-of-sight neutral hydrogen column densities yet measured. The stars were found independently by the ROSAT EUV, Montreal-Cambridge-Tololo, and Edinburgh-Cape surveys. Follow-up observations made using the Voyager 2 ultraviolet spectrometer reveal strong continua shortward of the 912Å Lyman limit from which we deduce that the neutral hydrogen column densities are 1.3 × 1017 and 2.0 × 1017 atoms cm−2. 相似文献
75.
This chapter gives a brief review on the theory of gamma-ray bursts (GRBs), including the models of multi-messengers (e.g., prompt multiwavelength electromagnetic emissions, high-energy neutrinos, ultra-high-energy cosmic rays, and gravitational waves) and central engines (in particular, mergers of binary neutron stars for short GRBs). For detailed reviews, please see (Piran in Phys. Rep. 314:575, 1999; Rev. Mod. Phys. 76:1143, 2004; Mészáros in Annu. Rev. Astron. Astrophys. 40:137, 2002; Rep. Prog. Phys. 69:2259, 2006; Zhang and Mészáros in Int. J. Mod. Phys. A 19:2385, 2004; Zhang in Chin. J. Astron. Astrophys. 7:1, 2007; Nakar in Phys. Rep. 442:166, 2007; Kumar and Zhang in Phys. Rep. 561:1, 2015). 相似文献
76.
Werner R. Balogh Hans J. Haubold 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,43(12):1847-1853
The United Nations Programme on Space Applications, implemented by the United Nations Office for Outer Space Affairs, promotes the benefits of space-based solutions for sustainable economic and social development. The Programme assists Member States of the United Nations to establish indigenous capacities for the use of space technology and its applications. In the past the Programme has primarily been focusing on the use of space applications and on basic space science activities. However, in recent years there has been a strong interest in a growing number of space-using countries to build space technology capacities, for example, the ability to develop and operate small satellites. In reaction to this development, the United Nations in cooperation with the International Academy of Astronautics has been organizing annual workshops on small satellites in the service of developing countries. Space technology related issues have also been addressed as part of various other activities of the Programme on Space Applications. Building on these experiences, the Office for Outer Space Affairs is now considering the launch of a new initiative, preliminarily titled the United Nations Basic Space Technology Initiative (UNBSTI), to promote basic space technology development. The initiative would be implemented in the framework of the Programme on Space Applications and its aim would be to help building sustainable capacities for basic space technology education and development, thereby advancing the operational use of space technology and its applications. 相似文献
77.
InSight Mars Lander Robotics Instrument Deployment System 总被引:1,自引:0,他引:1
A. Trebi-Ollennu Won Kim Khaled Ali Omair Khan Cristina Sorice Philip Bailey Jeffrey Umland Robert Bonitz Constance Ciarleglio Jennifer Knight Nicolas Haddad Kerry Klein Scott Nowak Daniel Klein Nicholas Onufer Kenneth Glazebrook Brad Kobeissi Enrique Baez Felix Sarkissian Menooa Badalian Hallie Abarca Robert G. Deen Jeng Yen Steven Myint Justin Maki Ali Pourangi Jonathan Grinblat Brian Bone Noah Warner Jaime Singer Joan Ervin Justin Lin 《Space Science Reviews》2018,214(5):93
The InSight Mars Lander is equipped with an Instrument Deployment System (IDS) and science payload with accompanying auxiliary peripherals mounted on the Lander. The InSight science payload includes a seismometer (SEIS) and Wind and Thermal Shield (WTS), heat flow probe (Heat Flow and Physical Properties Package, HP3) and a precision tracking system (RISE) to measure the size and state of the core, mantle and crust of Mars. The InSight flight system is a close copy of the Mars Phoenix Lander and comprises a Lander, cruise stage, heatshield and backshell. The IDS comprises an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, motor controller, arm-mounted Instrument Deployment Camera (IDC), lander-mounted Instrument Context Camera (ICC), and control software. IDS is responsible for the first precision robotic instrument placement and release of SEIS and HP3 on a planetary surface that will enable scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. This paper describes the design and operations of the Instrument Deployment Systems (IDS), a critical subsystem of the InSight Mars Lander necessary to achieve the primary scientific goals of the mission including robotic arm geology and physical properties (soil mechanics) investigations at the Landing site. In addition, we present test results of flight IDS Verification and Validation activities including thermal characterization and InSight 2017 Assembly, Test, and Launch Operations (ATLO), Deployment Scenario Test at Lockheed Martin, Denver, where all the flight payloads were successfully deployed with a balloon gravity offload fixture to compensate for Mars to Earth gravity. 相似文献
78.
Farzad Kamalabadi Jianqi Qin Brian J. Harding Dimitrios Iliou Jonathan J. Makela R. R. Meier Scott L. England Harald U. Frey Stephen B. Mende Thomas J. Immel 《Space Science Reviews》2018,214(4):70
The Ionospheric Connection Explorer (ICON) Far Ultraviolet (FUV) imager, ICON FUV, will measure altitude profiles of OI 135.6 nm emissions to infer nighttime ionospheric parameters. Accurate estimation of the ionospheric state requires the development of a comprehensive radiative transfer model from first principles to quantify the effects of physical processes on the production and transport of the 135.6 nm photons in the ionosphere including the mutual neutralization contribution as well as the effect of resonant scattering by atomic oxygen and pure absorption by oxygen molecules. This forward model is then used in conjunction with a constrained optimization algorithm to invert the anticipated ICON FUV line-of-sight integrated measurements. In this paper, we describe the connection between ICON FUV measurements and the nighttime ionosphere, along with the approach to inverting the measured emission profiles to derive the associated O+ profiles from 150–450 km in the nighttime ionosphere that directly reflect the electron density in the F-region of the ionosphere. 相似文献
79.
There have been many significant advances in understanding magnetic field reconnection as a result of improved space measurements
and two-dimensional computer simulations. While reviews of recent work have tended to focus on symmetric reconnection on ion
and larger spatial scales, the present review will focus on asymmetric reconnection and on electron scale physics involving
the reconnection site, parallel electric fields, and electron acceleration. 相似文献
80.
The information on the project being developed in Brazil for a flight to binary or triple near-Earth asteroid is presented.
The project plans to launch a spacecraft into an orbit around the asteroid and to study the asteroid and its satellite within
six months. Main attention is concentrated on the analysis of trajectories of flight to asteroids with both impulsive and
low thrust in the period 2013-2020. For comparison, the characteristics of flights to the (45) Eugenia triple asteroid of
the Main Belt are also given. 相似文献