CBERS-1卫星红外多光谱扫描仪主光学装置设计

文章介绍了CBERS -1卫星IRMSS主光学装置的设计 ,叙述了光学系统和结构选择、装配调试、像质的稳定性、可靠性问题。该装置在焦面Φ8mm范围内弥散园优于Φ0.010mm ,调制传递函数MTF优于0.91。     

Preparing for space: Increasing technical readiness of low-cost high-performance remote sensing using high-altitude ballooning

Two widely available, small size, weight and power camera systems were flown above 97 % of Earth’s atmosphere and showed utility in single filter vegetation and soil analysis in a space analogue environment. The experiment was conducted as a low-cost verification and test analogue to flying on vastly more expensive low Earth orbit missions. Normalised Difference Vegetation Index (NDVI) was used as the metric by which performance was analysed for ground calibration testing, low and near-space altitude remote sensing. Ground calibration testing with a laboratory-grade spectrometer revealed that both cameras were able to return consistent NDVI results, and high-altitude balloon flight allowed similar data capture from an environment similar to space. Although compressed captured imagery had been processed using gamma correction and pre-image processing, these were able to be corrected provided that access to radiometrically-calibrated data was available. The two hobbyist cameras were shown to return scientifically useful results, demonstrating performance, and additionally their utility for citizen science applications in the near-space environment.     

Examining the effects of anti-space weaponization arguments in the media: Some experimental findings from Canada

This study examines how political activists are framing the space weaponization debate in Canada and whether their arguments can influence public attitudes and perceptions about the issue. Eighty university students from two undergraduate courses were recruited as participants in a quasi-experiment. One class (n = 38) was exposed to the documentary Masters of Space, an episode of the Canadian Broadcasting Corporation's program The Nature of Things, and another class (n = 42) served as the control group. Pre-test and post-test questionnaires were used to measure the effects of viewing anti-weaponization arguments in the media, while also controlling for the influence of prior beliefs and background characteristics of participants. Results suggest that visually depicting the use of satellite technology in society can convince viewers that satellites are important to their way of life, but not necessarily to the defense of North America. Framing missile defense as a ‘space weapon in disguise’ also seemed to raise opposition to Canada's participation in continental missile defense. The findings, meanwhile, indicate that viewers respond strongly to the issue of space debris and that mobilizing support for joint military space projects may best be achieved by emphasizing the usefulness of these projects for locating and tracking such debris. In the end, media exposure seemed to help legitimize anti-weaponization arguments based more on rational self-interests than on idealistic beliefs. These findings can have implications for the way space policies are communicated to the public.     

Integration of GPS and low cost INS for pedestrian navigation aided by building layout

In outdoor environments, GPS is often used for pedestrian navigation by utilizing its signals for position computation, but in indoor or semi-obstructed environments, GPS signals are often unavailable. Therefore, pedestrian navigation for these environments should be realized by the integration of GPS and inertial navigation system （INS）. However, the lowcost INS could induce errors that may result in a large position drift. The problem can be minimized by mounting the sensors on the pedestrian＇s foot, using zero velocity update （ZUPT） method with the standard navigation algorithm to restrict the error growth. However, heading drift still remains despite using ZUPT measurements since the heading error is unobservable. Also, tbot mounted INS suffers from the initialization ambiguity of position and heading from GPS. In this paper, a novel algorithm is developed to mitigate the heading drift problem when using ZUPT. The method uses building lay- out to aid the heading measurement in Kalman filter, and it could also be combined for the initial- ization. The algorithm has been investigated with real field trials using the low cost Microstrain 3DM-GX3-25 inertial sensor, a Leica GS10 GPS receiver and a uBlox EVK-6T GPS receiver. It could be concluded that the proposed method offers a significant improvement in position accuracy for the long period, allowing pedestrian navigation for nearly40 min with mean position error less than 2.8 m. This method also has a considerable effect on the accuracy of the initialization.     

Estimation of the Love and Shida numbers: h2, l2 using SLR data for the low satellites

In this paper we present results for the global elastic parameters: Love number h₂ and Shida number l₂ derived from the analysis of Satellite Laser Ranging (SLR) data. SLR data for the two low satellites STELLA (H = 800 km) and STARLETTE (H = 810 km) observed during 2.5 years from January 3, 2005 until July 1, 2007 with 18 globally distributed ground stations were analyzed. The analysis was done separately for the two satellites. We do a sequential analysis and study the stability and convergence of the estimates as a function of length of the data set used.     

Venus observations from ENVISAT–SCIAMACHY: Measurements and modeling

This work shows the capability of observing Venus with a sensor originally designed for Earth remote sensing. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), onboard ENVISAT, successfully observed visible and near-infrared spectra from the Venusian atmosphere. The Venus spectra were simulated using a line-by-line radiative transfer model. The single scattering approximation was applied in order to consider the effects of an approximately 20 km-thick haze layer above the main cloud deck, which was considered as a reflecting cloud located in the upper atmosphere of the planet. CO₂ absorption lines could be distinguished in both observed and simulated spectra and a good agreement between them was also found.     

高阶带谐摄动下卫星相对运动精确动力学模型

在考虑J 2 项摄动的卫星相对运动精确动力学模型基础上,推导了可以精确到任意阶带谐非球形引力摄动的卫星相对运动精确动力学模型,还给出了一组简洁的基于参考卫星轨道要素（Reference Satellite Variables）的微分方程,能够描述精确到任意阶带谐非球形引力的卫星地球轨道运动。由于在模型推导过程中没有引入任何简化,新推导的结果适用于任意偏心率的地球轨道。     

改进的卫星广播星历参数模型及其算法

考虑导航卫星受地球周期性的摄动力影响,提出了一种改进的导航卫星星历参数模型,给出了模型参数的计算方法和用该模型外推卫星轨道的计算步骤。仿真计算结果表明：该广播星历参数模型外推能力强,可较好地拟合卫星运动轨道。     

An alternative computation of a gravity field model from GOCE

GOCE is the first satellite with a gravitational gradiometer (SGG). This allows to determine a gravity field model with high spatial resolution and high accuracy. Four of the six independent components of the gravitational gradient tensors (GGT) are measured with high accuracy in the so-called measurement band (MB) from 5 to 100 mHz by the GOCE gradiometer. Based on more than 1 year of GOCE measurements, two gravity field models have been derived. Here, we introduce a strategy for spherical harmonic analysis (SHA) from GOCE measurements, with a bandpass filter applied to the SGG data, combined with orbit analysis based on the integral equation approach, and additional constraints (or stabilization) in the polar areas where no observation is available due to the orbit geometry. In addition, we combined the GOCE SGG part with a set of GRACE normal equations. This improves the accuracy of the gravity field in the long-wavelength parts, due to the complementarity of GOCE and GRACE. Comparison with other models and with external data shows that our results are rather close to the GPS-levelling data in well-selected test regions, with an uncertainty of 4–7 cm, for truncation at degree 200.     

船岸网络时延测量误差原因分析

简单介绍了测量船船岸通信网络组成,重点介绍了NTP（网络时间协议）和PTP（精密时间协议）这2种网络时间同步协议。针对改建后的船岸网络时延测量误差进行分析和研究,提出基于TWSTFT（卫星双向时间频率传输）技术模型的网络时延测量方法,测量结果误差小于3ms,满足测控任务实时性要求,为提高测控网的测控精度提供有益参考。