Mars Global Surveyor Measurements of the Martian Solar Wind Interaction

The solar wind at Mars interacts with the extended atmosphere and small-scale crustal magnetic fields. This interaction shares elements with a variety of solar system bodies, and has direct bearing on studies of the long-term evolution of the Martian atmosphere, the structure of the upper atmosphere, and fundamental plasma processes. The magnetometer (MAG) and electron reflectometer (ER) on Mars Global Surveyor (MGS) continue to make many contributions toward understanding the plasma environment, thanks in large part to a spacecraft orbit that had low periapsis, had good coverage of the interaction region, and has been long-lived in its mapping orbit. The crustal magnetic fields discovered using MGS data perturb plasma boundaries on timescales associated with Mars' rotation and enable a complex magnetic field topology near the planet. Every portion of the plasma environment has been sampled by MGS, confirming previous measurements and making new discoveries in each region. The entire system is highly variable, and responds to changes in solar EUV flux, upstream pressure, IMF direction, and the orientation of Mars with respect to the Sun and solar wind flow. New insights from MGS should come from future analysis of new and existing data, as well as multi-spacecraft observations.     

Modeling of the Magnetospheric Response to the Dynamic Solar Wind

We discuss quasi-static and dynamic models of the magnetotail response to perturbations imposed by the solar wind, focusing particularly on the formation of thin current sheets, their structure and breakup.     

The Strength and Structure of the Coronal Magnetic Field

I discuss a method for determining the strength and spatial structure of the coronal magnetic field by observations of the Faraday rotation of a radio galaxy which is in conjunction with the Sun. Given a knowledge of the plasma density in the outer corona, and the magnetic field sector structure (both independently available), the strength of the coronal field can be determined, as well as the magnitude of spatial variations on scales of 1000 km to several solar radii. Such knowledge is crucial for testing computational models of the solar corona, which are prominently featured in this meeting. Results are presented from observations with the Very Large Array radio telescope of the radio galaxy 3C228 on August 16, 2003, when the line of sight to the source was at heliocentic distances of 7.1−6.2R _⊙. The observations are consistent with a coronal magnetic field which is proportional to the inverse square of the distance in the range 6 ≤ r ≤ 10R _⊙, and has a value of 39 mG at 6.2R _⊙. The Faraday rotation is uniform across the source, indicating an absence of strong plasma inhomogeneity on spatial scales up to 35,000 km.     

SR107-ZK白漆在轨飞行性能退化分析

根据北斗一号卫星天线在轨的实际飞行温度,反推出了SR107-ZK白漆的太阳吸收比αs退化曲线,并根据该曲线外推,得到了8年寿命末期的太阳吸收比αs,预测了卫星寿命末期天线反射面的最高温度。     

夹芯的典型参数对夹层板受迫振动影响分析

根据伽辽金法,用Matlab/Simulink软件对推导的经典板假设理论、一阶剪切理论蜂窝夹层板运动方程进行了数值仿真。简单算例的计算结果表明两者基本一致。基于一阶剪切理论讨论了蜂窝夹芯泊松比对蜂窝夹层板低阶频率的影响。发现当泊松比接近1时对频率响应有显著的影响。     

Solar Energetic Particle Composition, Energy Spectra, and Space Weather

Recent progress in measuring the composition and energy spectra of solar energetic particles (SEPs) accelerated by CME-driven shocks is reviewed, including a comparison of the observed charge-to-mass dependence of breaks in SEP spectra with model predictions. Also discussed is a comparison of SEP and CME kinetic energies in seventeen large SEP events, and estimates of the SEP radiation dose that astronauts would be subject to once they venture outside the protective cover of Earth’s magnetosphere.     

Solar Radio Bursts with Drifting Stripes in Emission and Absorption

This review covers fairly comprehensively experimental and theoretical research on the fine structure of types zebra pattern (ZP) and fiber bursts (FB) in solar type II + IV radio bursts. The basic attention is given to the latest experimental data. A comparative analysis of several recent solar type IV radio outbursts with these fine structure in dynamical radio spectra is carried out using available ground-based and satellite data (Yohkoh, SOHO, TRACE, RHESSI). New data on microwave zebra structures and fiber bursts testifies that they are analogous to similar structures observed at meter wavelengths. The discovery of the superfine structure, in the form of millisecond spikes is the most significant new effect in the cm range. All basic theoretical models of the zebra pattern and fiber bursts are discussed critically. Two main models are studied for their interpretation: (i) interactions between electrostatic plasma waves and whistlers, (ii) radio emission at double plasma resonance (DPR). The relative significance of several possible mechanisms remains uncertain.     

Observation of Transition Region Fine Structures with Soho/Sumer

We present a preliminary analysis of two quiet Sun transition region areas observed with the SOHO/SUMER spectrometer, using lines from oxygen, nitrogen and silicon. The average quiet Sun physical parameters are studied as a function of line intensity. Systematic variations of line position and width with increasing intensity are found. A large number of small-scale active points have been observed, and preliminary analysis of the physical properties and dynamics of these active features is presented. A jet-like structure, found in an active point, is also investigated and its velocity along the line of sight determined. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Solar Wind and the Sun in the Past

Exposure to the solar wind can have significant long term consequences for planetary atmospheres, especially for planets such as Mars that are not protected by global magnetospheres. Estimating the effects of solar wind exposure requires knowledge of the history of the solar wind. Much of what we know about the Sun’s past behavior is based on inferences from observations of young solar-like stars. Stellar analogs of the weak solar wind cannot be detected directly, but the interaction regions between these winds and the interstellar medium have been detected and used to estimate wind properties. I here review these observations, with emphasis on what they suggest about the history of the solar wind.     

On the Radial Evolution of Alfvénic Turbulence in the Solar Wind

The observations at different solar distances and latitudes, collected in the past three decades, and the results obtained from more and more sophisticated numerical simulations allowed us to reach a good understanding on many aspects of the complex phenomenon of solar wind turbulence. Moreover, new interesting insights in the theory of turbulence have been obtained, in the past decade, from the point of view that considers a turbulent flow as a complex system, where chaotic behavior and well-established scaling laws coexist. This review aims to provide a quick overview on the state of art in this research field with particular focus on local generation mechanisms.