视场内导航星分布的预测

给出理想情况下视场内导航星分布模型的基础上,根据敏感器的星等门限和测量精度,进一步实现了存在星等误差情况下导航星分布的预测,使得该模型更为接近真实的情况.实验表明,采用该模型获得的分布与用MonteCarlo方法获得的统计分布极为接近,证明了该模型的正确性和有效性,从而得到了一种事先对视场内导航星分布作出较为准确估计的新的方法.     

An Improved Double r-iteration IOD Method for GEO UCTs Based on SBSS System

The purpose of initial orbit determination, especially in the case of angles-only data for observation, is to obtain an initial estimate that is close enough to the true orbit to enable subsequent precision orbit determination processing to be successful. However, the classical angles-only initial orbit determination methods cannot deal with the observation data whose Earth-central angle is larger than 360°. In this paper, an improved double r-iteration initial orbit determination method to deal with the above case is presented to monitor geosynchronous Earth orbit objects for a spacebased surveillance system. Simulation results indicate that the improved double r-iteration method is feasible, and the accuracy of the obtained initial orbit meets the requirements of re-acquiring the object.     

Strategic Priority Program on Space Science

In 1957, the launch of the first artificial satellite ushered in a new era for modern space science.The past 50 years' developments in China's space science have witnessed many major missions, and substantial progress has been achieved in space science study, exploration technology as well as experiment technology. Strategic Priority Program on Space Science was officially started in 2011. Through both self-developed space science missions and those with international cooperation,it is expected that the innovative breakthroughs will be realized, leapfrog development of related high-tech will be achieved to establish the important strategic status of space science in national development. To sum up, the implementation of the Strategic Priority Program on Space Science will definitely promote the rapid development of China's space science endeavor, making contributions to China's development and the progress of human civilization.     

基于畸变影响的动态星模拟器星点位置修正方法

介绍了动态星模拟器工作原理及星点位置误差计算方法,提出一种基于星模拟器自身光学系统畸变影响的星点位置修正方法,根据星点位置修正原理,建立修正模型并推导出相应公式. 通过对动态星模拟器光学系统进行分析,在畸变曲线基础上利用Matlab拟合得出光学系统视场与星点位置修正量的关系曲线,通过确定星点位置修正临界视场并选取适当修正范围,根据公式对星点位置进行修正以满足星模拟器的设计指标,利用该修正方法能够有效降低对动态星模拟器光学系统畸变设计的要求,为动态星模拟器误差修正提供有效方法.     

星载光学敏感器受天体干扰的可能性分析

各种用途的星载光学敏感器均可能受到日、月、地等天体进入敏感区所形成的干扰.对光轴固定于星体的星敏感器,以及光轴在空间中保持方位不变的天文望远镜两类星载光学敏感器,根据敏感锥面和天体锥面之间的空间位置关系,导出了天体干扰的发生条件,给出了预测干扰发生时间的实用计算公式.     

Observation of the double sodium layer over Haikou,China by Lidar

A Double Sodium Layer (DSL) structure was observed during the night of August 22, 2011 over Haikou, China (20°N, 110°E) by Na lidar. This DSL comprised a typical sodium layer at altitudes of 80~105km and a higher sodium layer at altitudes of 105~115km in about 0.5 h. A wavelength of 589nm dye laser pumped by a Nd: YAG laser was used to make the measurement. The backscattered fluorescence photons from the sodium layer were collected by a telescope with a primary mirror of 1000mm in diameter. The sodium density of these layers during the nighttime observation in the Mesosphere and Lower-Thermosphere (MLT) was studied.     

GOCE star tracker attitude quaternion calibration and combination

We analyse the inter-boresight angles (IBA) measured by the star trackers on board the GOCE satellite and find that they exhibit small offsets of 7–9″ with respect to the ones calculated from the rotation of the star tracker reference frames to the satellite reference frame. Further, we find small variations in the offsets with a peak-to-peak amplitude of up to 8″, which correlate with variations of the star trackers’ temperatures. Motivated by these findings, we present a method for combining the attitude quaternions measured by two or more star trackers that includes an estimation of relative attitude offsets between star trackers as a linear function of temperature. The method was used to correct and combine the star tracker attitude quaternions within the reprocessing of GOCE data performed in 2018. We demonstrate that the IBA calculated from the corrected star tracker attitude quaternions show no significant offsets with respect to the reference frame information. Finally, we show that neglecting the star tracker attitude offsets in the processing would result in perturbations in the gravity gradients that are visible at frequencies below 2?mHz and have a magnitude of up to 90?mE. The presented method avoids such perturbations to a large extent.     

A triangle voting algorithm based on double feature constraints for star sensors

A novel autonomous star identification algorithm is presented in this study. In the proposed algorithm, each sensor star constructs multi-triangle with its bright neighbor stars and obtains its candidates by triangle voting process, in which the triangle is considered as the basic voting element. In order to accelerate the speed of this algorithm and reduce the required memory for star database, feature extraction is carried out to reduce the dimension of triangles and each triangle is described by its base and height. During the identification period, the voting scheme based on double feature constraints is proposed to implement triangle voting. This scheme guarantees that only the catalog star satisfying two features can vote for the sensor star, which improves the robustness towards false stars. The simulation and real star image test demonstrate that compared with the other two algorithms, the proposed algorithm is more robust towards position noise, magnitude noise and false stars.