High-accuracy same-beam VLBI observations using Shanghai and Urumqi telescopes

The same-beam VLBI observations of Rstar and Vstar, which were two small satellites of Japanese lunar mission, SELENE, were successfully performed by using Shanghai and Urumqi 25-m telescopes. When the separation angle between Rstar and Vstar was less than 0.1 deg, the differential phase delay of the X-band signals between Rstar and Vstar on Shanghai-Urumqi baseline was obtained with a very small error of 0.15 mm rms, which was reduced by 1-2 order compared with the former VLBI results. When the separation angle was less than 0.56 deg, the differential phase delay of the S-band signals was also obtained with a very small error of several mm rms. The orbit determination for Rstar and Vstar was performed, and the accuracy was improved to a level of several meters by using VLBI and Doppler data. The high-accuracy same-beam differential VLBI technique is very useful in orbit determination for a spacecraft, and will be used in orbit determination for Mars missions of China Yinghuo-1 and Russia Phobos-grunt.

基于带状弹簧的空间望远镜精密展开技术进展

采用带状弹簧构造的可折叠多杆并联结构对卡塞格林型望远镜的次镜进行支撑，并结合在轨调节，可以实现口径<1m的可展开空间望远镜。描述了基于带状弹簧的可展开空间望远镜的结构特点，介绍了近年来发表的四杆支撑、八杆支撑、三杆支撑和六杆支撑等4种基于带状弹簧的空间望远镜精密展开技术的研究进展。建议针对带状弹簧空间望远镜的精密展开技术，应进一步开展结构动力学建模、结构优化以及误差的光电测量和校正等方面的研究。此外，在模拟微重力环境下展开实验也有助于推动展开动力学和展开精度的研究，而非对称展开结构将是今后该项技术的研究方向之一。认为开展基于带状弹簧的空间望远镜精密展开技术的研究将促进基于微小卫星平台的高分辨率遥感成像和自由空间光通信技术的发展。

Superluminal radio source PKS 0420-014

The very long baseline interferometry result of a superluminal radio source PKS 0420-014 at 5 GHz with Shanghai (China), Urumqi (China), Note (Italy), and HartRAO (South Africa) telescopes is presented. Proper motions of the relativistic jet components in the source are calculated. Based on the Self-Compton emission in a uniform spherical model, the beaming parameters of the source are estimated. The results show that PKS 0420-014 has a high Doppler factor of 9.3, a Lorentz factor of 6.5, and a small angle of 5.5 degrees to the line of sight.

Radar interferometer measurements of space debris using the Evpatoria RT-70 transmitter

The ability of the Evpatoria RT-70 radar complex to perform research on space debris was investigated in four trial experiments during 2001-2003. The echo-signals of 25 objects at geostationary, highly elliptical and medium-altitude orbits were recorded on magnetic tapes at radio telescopes in Russia, Italy, China and Poland. The multi-antenna system configuration gives potential to supplement the classic radar data with precise angular observations using the technique of Very Long Baseline Interferometry. The first stage of such processing was fulfilled by the correlator in N. Novgorod, Russia. The cross-correlation of transmitted and received signals was obtained for the 11 objects on the Evpatoria-Bear Lakes, Evpatoria-Urumqi and Evpatoria-Noto baselines. This activity also promoted developing the optical observations of geostationary objects, conducted for the improvement of the radar target ephemerides. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

96 MEV能量下~(16)O + ~(94)Ni反应机制研究

The pro sectile-like fragments of ~(16)O + ~(64)Ni Reaction (Elab = 96 MeV) were measured by using ionization chamber telescopes. The countour plots of d~36/dndEdz in TKE-θ plane angular distribution integrating over different TKE window. The z-distribution and angular distributions of different fragments from He to O were obtained. The main mechanisms dominating in this reaction were discussed