Angle-Independent Doppler Velocity Measurement

When the angle between the target heading and the range vector is not known a priori, a Doppler velocity radar must estimate them simultaneously by utilizing a longer section of the track. The conventional least squares iterative solution is compared with a new explicit alogorithm which utilizes range-rate derivatives. It is shown that the explicit algorithm is biased but is less sensitive to noise. The bias, however, can be estimated and removed. Hence, the computationally simpler explicit velocity estimation method yields better performance. An analytical closed form expression for the resulting mean square estimation error and simulation results are given.     

Atmospheric Escape and Evolution of Terrestrial Planets and Satellites

The origin and evolution of Venus’, Earth’s, Mars’ and Titan’s atmospheres are discussed from the time when the active young Sun arrived at the Zero-Age-Main-Sequence. We show that the high EUV flux of the young Sun, depending on the thermospheric composition, the amount of IR-coolers and the mass and size of the planet, could have been responsible that hydrostatic equilibrium was not always maintained and hydrodynamic flow and expansion of the upper atmosphere resulting in adiabatic cooling of the exobase temperature could develop. Furthermore, thermal and various nonthermal atmospheric escape processes influenced the evolution and isotope fractionation of the atmospheres and water inventories of the terrestrial planets and Saturn’s large satellite Titan efficiently.     

光纤陀螺标度因数及零偏温度误差补偿研究

首先分析了光纤陀螺产生温度误差的机理,在此基础上分别指出标度因数与零偏的误差补偿模型,提出了一种利用一组数据同时补偿标度因数及零偏的方法,直接表示输入与标度因数零偏补偿后的关系。最后通过实验验证了该方法不仅能够有效地补偿陀螺的温度误差,且其补偿精度优于原单独补偿的方法,同时该方法仅需一次温度实验,节省实验成本,具有较大的现实意义。     

Cosmic Rays and Earth – A Summary

Cosmic rays provide a diagnostic tool to analyze processes in interplanetary space and at the Sun. Cosmic rays also directly affect the terrestrial environment and serve as indicators of solar variability and non anthropogenic climatic changes on Earth at present and in the distant past. After the invention of the neutron monitor by John A. Simpson in 1948, an international network of cosmic ray detectors developed in a cooperative effort to examine temporal and spatial variations in our space environment. The resulting datasets represent the longest continuous, high time resolution series of particle radiation measurement in space science. At present, the neutron monitor network is complemented by spacecraft instrumentation to study solar-terrestrial correlated phenomena. This revised version was published online in August 2006 with corrections to the Cover Date.     

A Problem of choosing an optimal number of information unmanned aerial vehicles

Using formalism of the queueing theory, we propose two-objective models for optimizing the number of unmanned aerial vehicles (UAV) designed for remote monitoring (reconnaissance) of certain regions. A model that takes into account the UAV failure in performing a flight mission is considered. The numerical method and examples of solving problems stated are presented.     

Interstellar Mapping and Acceleration Probe (IMAP): A New NASA Mission

The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. While seemingly disparate, these are intimately coupled because particles accelerated in the inner heliosphere play critical roles in the outer heliospheric interaction. Selected by NASA in 2018, IMAP is planned to launch in 2024. The IMAP spacecraft is a simple sun-pointed spinner in orbit about the Sun-Earth L1 point. IMAP’s ten instruments provide a complete and synergistic set of observations to simultaneously dissect the particle injection and acceleration processes at 1 AU while remotely probing the global heliospheric interaction and its response to particle populations generated by these processes. In situ at 1 AU, IMAP provides detailed observations of solar wind electrons and ions; suprathermal, pickup, and energetic ions; and the interplanetary magnetic field. For the outer heliosphere interaction, IMAP provides advanced global observations of the remote plasma and energetic ions over a broad energy range via energetic neutral atom imaging, and precise observations of interstellar neutral atoms penetrating the heliosphere. Complementary observations of interstellar dust and the ultraviolet glow of interstellar neutrals further deepen the physical understanding from IMAP. IMAP also continuously broadcasts vital real-time space weather observations. Finally, IMAP engages the broader Heliophysics community through a variety of innovative opportunities. This paper summarizes the IMAP mission at the start of Phase A development.