排序方式: 共有34条查询结果,搜索用时 46 毫秒
1.
Stephen W. Bougher Pierre-Louis Blelly Michael Combi Jane L. Fox Ingo Mueller-Wodarg Aaron Ridley Raymond G. Roble 《Space Science Reviews》2008,139(1-4):107-141
Numerical modeling tools can be used for a number of reasons yielding many benefits in their application to planetary upper atmosphere and ionosphere environments. These tools are commonly used to predict upper atmosphere and ionosphere characteristics and to interpret measurements once they are obtained. Additional applications of these tools include conducting diagnostic balance studies, converting raw measurements into useful physical parameters, and comparing features and processes of different planetary atmospheres. This chapter focuses upon various classes of upper atmosphere and ionosphere numerical modeling tools, the equations solved and key assumptions made, specified inputs and tunable parameters, their common applications, and finally their notable strengths and weaknesses. Examples of these model classes and their specific applications to individual planetary environments will be described. 相似文献
2.
Many competent sources have been predicting an increasing shortage of graduate engineers to perform needed research and development work in the United States. Consequently, many industrialists, educators, and government officials have been advocating an increased enrollment of students in the engineering curriculum in college in a greater effort to produce more engineers. This paper examines the assumptions behind the projected manpower shortage, and proposes some rather unique and occasionally radical alternatives to the solution of a manpower deficit. The paper, and the solutions, may produce violent controversy, but at least the material is not the usual dull rehash so often seen of late. 相似文献
3.
Carole Jordan 《Space Science Reviews》1972,13(4-6):595-605
Conclusions During the past three years there have been significant extensions of the solar data available. Over most of the solar spectrum between 1 – 2200 the new or improved observations have led to interesting problems in line identifications. The identifications have in turn led to new methods of determining the physical conditions in the solar atmosphere, eg electron density determinations from the Hei like ion intercombination line to forbidden line ratio (Gabriel and Jordan, 1969b). The majority of the strong lines have now been identified, either by theoretical considerations or from the extensive laboratory data which have recently become available. However, weak lines may also aid the understanding of the chromosphere and corona and work on the identifications of all remaining features observed must continue. 相似文献
4.
The multifaceted Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR) was successfully flown twice in 1994 aboard the Shuttle Endeavour as part of an international imaging radar mission. The United States SIR-C operated at L- and C-band, each with multiple polarization, utilizing an active phased array antenna. The German/Italian X-SAR operated at X-band with a single polarization. SIR-C and X-SAR operated synchronously to collect data over common sites. Data were collected for repeat-track interferometric processing at all three frequencies. A total of 143 hours (93 terabits) of SAR data were digitally recorded on tape over the two flights for subsequent processing in the U.S., Germany, and Italy. This advanced multifrequency/multipolarization system has produced a rich radar data set for Earth scientific investigation and demonstration of spaceborne radar remote sensing capabilities 相似文献
5.
David Mimoun Naomi Murdoch Philippe Lognonné Kenneth Hurst William T. Pike Jane Hurley Tanguy Nébut William B. Banerdt SEIS Team 《Space Science Reviews》2017,211(1-4):383-428
The SEIS (Seismic Experiment for Interior Structures) instrument on board the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. The InSight noise model is a key tool for the InSight mission and SEIS instrument requirement setup. It will also be used for future operation planning. This paper presents the analyses made to build a model of the Martian seismic noise as measured by the SEIS seismometer, around the seismic bandwidth of the instrument (from 0.01 Hz to 1 Hz). It includes the instrument self-noise, but also the environment parameters that impact the measurements. We present the general approach for the model determination, the environment assumptions, and we analyze the major and minor contributors to the noise model. 相似文献
7.
C. Jordan 《Space Science Reviews》1981,29(4):363-365
A brief summary is given of observations which will be required to investigate further the structure and energy balance of active regions.Proceedings of the Conference Solar Physics from Space, held at the Swiss Federal Institute of Technology Zurich (ETHZ), 11–14 November 1980. 相似文献
8.
The Mars Program Plan includes an integrated and coordinated set of future candidate missions and investigations that meet fundamental science objectives of NASA and the Mars Exploration Program (MEP). At the time this paper was written, these possible future missions are planned in a manner consistent with a projected budget profile for the Mars Program in the next decade (2007-2016). As with all future missions, the funding profile depends on a number of factors that include the exact cost of each mission as well as potential changes to the overall NASA budget. In the current version of the Mars Program Plan, the Astrobiology Field Laboratory (AFL) exists as a candidate project to determine whether there were (or are) habitable zones and life, and how the development of these zones may be related to the overall evolution of the planet. The AFL concept is a surface exploration mission equipped with a major in situ laboratory capable of making significant advancements toward the Mars Program's life-related scientific goals and the overarching Vision for Space Exploration. We have developed several concepts for the AFL that fit within known budget and engineering constraints projected for the 2016 and 2018 Mars mission launch opportunities. The AFL mission architecture proposed here assumes maximum heritage from the 2009 Mars Science Laboratory (MSL). Candidate payload elements for this concept were identified from a set of recommendations put forth by the Astrobiology Field Laboratory Science Steering Group (AFL SSG) in 2004, for the express purpose of identifying overall rover mass and power requirements for such a mission. The conceptual payload includes a Precision Sample Handling and Processing System that would replace and augment the functionality and capabilities provided by the Sample Acquisition Sample Processing and Handling system that is currently part of the 2009 MSL platform. 相似文献
9.
Jordan Maxwell Hanspeter Schaub 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(11):3478-3488
The feasibility of using electrostatic forces to stabilize a close-proximity leader-follower formation is investigated. The leader craft is equipped with a set of affixed spheres whose charge is modulated to hold the charged follower craft along a proscribed trajectory to its nominal leader-relative position. This charge structure and the follower craft are constrained to remain in the plasma wake generated behind all LEO craft because the more-dense ambient plasma outside the wake prevents object charging and electric field propagation. Once the formation is achieved, a controlled electric field is generated by the leader to counter relative accelerations from perturbations like differential drag and solar radiation pressure, holding the follow near its nominal position. Two controllers are derived for the system described, incorporating Coulomb accelerations and linearized gravity and drag accelerations. Simulations are run under unmodeled perturbations and sensor noise for different scenarios, demonstrating the challenges and benefits associated with electrostatic actuation. 相似文献
10.