Solar System Magnetospheres

This article proposes a short review of our present knowledge of solar system magnetospheres, with the purpose of placing the study of Saturn’s magnetosphere in the context of a comparative approach. We describe the diversity of solar system magnetospheres and the underlying causes of this diversity: nature and magnetization state of the planetary obstacle, presence or not of a dense atmosphere, rotation state of the planet, existence of a system of satellites, rings and neutral gas populations in orbit around the planet. We follow the “russian doll” hierarchy of solar system magnetospheres to briefly describe the different objects of this family: the heliosphere, which is the Sun’s magnetosphere; the “elementary” magnetospheres of the inner planets, Earth and Mercury; the “complex” magnetospheres of the giant planets, dominated by planetary rotation and the presence of interacting objects within their magnetospheric cavities, some of which, like Ganymede, Io or Titan, produce small intrinsic or induced magnetospheres inside the large one.We finally describe the main original features of Saturn’s magnetosphere as we see them after the Voyager fly-bys and before the arrival of Cassini at Saturn, and list some of the key questions which Cassini will have to address during its four-year orbital tour.     

An in situ laser induced breakdown spectroscope (LIBS) for Chandrayaan-2 rover: Ablation kinetics and emissivity estimations

A miniaturized in situ laser induced breakdown spectroscope-LIBS is one of the two lunar rover payloads to be flown in India’s next lunar mission Chandrayaan-2, with an objective to carry-out a precise qualitative and quantitative elemental analyses of lunar regolith at the proximity of the landing region. As per the imposed mission constraints and the executed design optimization studies, a compact and light-weight LIBS prototype model is developed at our premises. This paper mainly concerns with the estimation of theoretical aspects; especially on evaluation of elemental ablation parameters and signal-to-noise ratio (SNR) calculations for the designed instrument. Theoretical estimations and simulations yielded an incident laser power density of the order of 5 × 10¹⁰ W/cm² on the target surface at a defined lens-to-surface distance (LTSD) of 200 mm and revealed an SNR > 100 for most of the elements under consideration. This paper also addresses the impact of LTSD variation on detection capability. The estimation of plasma-temperatures was carried out utilizing the emission spectra obtained under high vacuum environments employing the LIBS laboratory model. Experimental investigations and the performed theoretical estimations asserted the successful operation of the configured LIBS instrument for in situ elemental analyses on lunar surface.     

高超声速飞行器表面气动热和粘性摩擦力计算

本文给出了高超声速飞行器表面摩阻和传热系数 (斯坦顿数 )的计算结果。采用两种方法平面切面法亦即二维边界层近似法和工程方法计算了飞行器高超声速绕流的粘性效应 ,并对两种方法的计算结果作了仔细的比较。由文可见 ,对于在稠密大气层内 ,沿轨道运行头速度恒定的高超声速有翼飞行器 ,能够用本文所采用的两种方法计算其表面摩阻和热载荷。此二法可成功地应用于绕复杂形状物体的流动参数计算。     

Extreme deviations of landing parameters for heavy aircraft

We estimate the statistic characteristics and extreme deviations of the state vector components for the Ilyushin Il 96–300 systems at automatic landing.     

Computer-aided design of blank forging production facilities for aircraft engine compressor blades

The computer-aided design (CAD) system is specified for the preproduction engineering of the aircraft engine compressor blades. This system is characterized by a high quality of designing the finishing cutoff and reducing dies. It is shown that a high level of unification and integration in CAD permits the time of designing the punch tool sets to be significantly reduced.     

Study of isotropic shell survivability by the analytical method

Shells with a through-thickness macrocrack are considered. The algorithms for determining the specific radius r _c in the crack-tip vicinity, the limiting load p _c (the attainment of which makes the crack unstable), and the direction of macrocrack growth θ _c are presented. We study the carrying capacity of a lengthy circular cylindrical shell under the internal pressure and with an arbitrarily oriented macrocrack.     

Structural regularities of stress-strain state variations in a hardened surface of turbine blade roots at service conditions

Some results obtained in the course of structural investigations with the use of the methods of scanning electron microscopy and X-ray structure analysis of operating temperature influence upon dynamics of the hardened state relaxation in the turbine blade roots are discribed. Also considered are the data on determining the residual surface stresses by Davidenkov’s method and that of the X-ray diffractometry.     

A Study of Vibrations of Space Station Structure Elements on the Basis of Video Information

Cosmic Research - The results of the Sreda–MKS space experiment showed that visual data on the vibrations of the ISS structural elements allow one to acquire quantitative characteristics of...     

The Galaxy Cluster Mass Scale and Its Impact on Cosmological Constraints from the Cluster Population

Space Science Reviews - The QB50 mission is a satellite constellation designed to carry out measurements at between 200–380 km altitude in the ionosphere. The multi-needle Langmuir probe...     

X-rays from the first massive black holes

X-ray studies of high-redshift (z > 4) active galaxies have advanced substantially over the past few years, largely due to results from the new generation of X-ray observatories. As of this writing X-ray emission has been detected from nearly 60 high-redshift active galaxies. This paper reviews the observational results and their implications for models of the first massive black holes, and it discusses future prospects for the field.