LISA: Heliocentric formation design for the laser interferometer space antenna mission

The LISA (Laser Interferometer Space Antenna) mission has been selected by the European Space Agency’s Science Programme Committee as the third large-class mission of the Cosmic Vision Programme, addressing the science theme of the Gravitational Universe. With a planned launch date in 2034, LISA will be the first ever space-borne Gravitational Wave observatory, relying on laser interferometry between three spacecraft orbiting the Sun in a triangular formation. Airbus is currently leading an industrial Phase A system study on behalf of the European Space Agency. The paper will address the astrodynamics challenges associated with the LISA constellation design, driven by tight requirements on the geometric quality metrics of the near equilateral formation.     

散斑直接检测技术

本文首次提出了用斑点列阵取代无规分布的散斑,以斑点定位对斑点作直接检测的原理和方法。实验结果表明,作为不同于散斑干涉计量和ESPI(Electronic Speckle Patterm Interferometry)技术的一种新方法,以斑点定位作直接检测是完全可行的。     

量块的电脑化测试装置

接触式干涉仪是计量部门测试三等量块的法定仪器。本文介绍了一种基于接触式干涉仪的量块自动测试系统，它以光电探测替代目视估测，免除操作人员的视力疲劳，并能自动处理数据。软件系统以最新的国家检定标准编制，易学好用。     

DISTRIBUTED OPTIC－FIBER FORCE SENSOR BASED ON MODE COUPLING EFFECTS IN HIGH－BIREFRINGENT FIBER

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Numerical simulation of time delay interferometry for a LISA-like mission with the simplification of having only one interferometer

In order to attain the requisite sensitivity for LISA, laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. In a previous paper (Dhurandhar, S.V., Nayak, K.R., Vinet, J.-Y. Time delay interferometry for LISA with one arm dysfunctional. Class. Quantum Grav. 27, 135013, 2010), we have found a large family of second-generation analytic solutions of time delay interferometry with one arm dysfunctional, and we also estimated the laser noise due to residual time-delay semi-analytically from orbit perturbations due to Earth. Since other planets and solar-system bodies also perturb the orbits of LISA spacecraft and affect the time delay interferometry (TDI), we simulate the time delay numerically in this paper for all solutions with the generation number n ? 3. We have worked out a set of 3-year optimized mission orbits of LISA spacecraft starting at January 1, 2021 using the CGC2.7 ephemeris framework. We then use this numerical solution to calculate the residual optical path differences in the second-generation solutions of our previous paper, and compare with the semi-analytic error estimate. The accuracy of this calculation is better than 1 cm (or 30 ps). The maximum path length difference, for all configuration calculated, is below 1 m (3 ns). This is well below the limit under which the laser frequency noise is required to be suppressed. The numerical simulation in this paper can be applied to other space-borne interferometers for gravitational wave detection with the simplification of having only one interferometer.     

移相干涉中移相误差测量与补偿

移相干涉测量中对移相器的移相误差进行测量与补偿是提高该测量方法准确度的有效手段。通过研究移相干涉移相误差对测量结果的影响,提出了测量移相器工作时位移与角度变化的方法,建立了相应的实验测量装置,实现了移相器的位移及角度变化的测量。根据移相器中位移与角度的数学关系完成了移相误差的补偿,修正后的移相效果在移相干涉仪中采用了整周期移相干涉图灰度差值的方法进行了验证。     

Ka数字波束合成-合成孔径雷达顺轨干涉性能分析

顺轨干涉-合成孔径雷达(ATI-SAR)能够利用多普勒信息对宽幅场景径向速度进行测量,然而目前既有的顺轨干涉性能分析主要是针对两组单通道数据实现误差分解,并没有考虑距离向数字波束合成-合成孔径雷达(DBF-SAR)。为实现面向高分宽幅应用的顺轨干涉测速应用,分析在毫米波频段收发天线轻量化、集成化优势下的毫米波距离向多通道合成SAR顺轨干涉系统,评估通道间相位误差、波达角估计误差等因素对干涉相位相干性的影响。结果表明:在一定的弱散射场景下,在Ka频段实现的DBF技术能够利用较少的通道数有效改善测速性能,为后续的多通道顺轨干涉数据分析提供定量化参考。     

北斗GEO卫星CEI相时延解算方法研究

连线端站干涉测量(connected element interferometry，CEI)是高精度测角技术，在中高轨卫星、月球及深空航天器定轨定位中有良好的应用前景。基于CEI技术特点，提出了一种新的测量方法，即在相干测距模式下利用测距音和载波信号作为信号源进行连线端站干涉测量。构建了CEI试验系统对北斗GEO卫星进行观测，利用相干测距模式下的下行信号解算群时延、相时延。利用北斗GEO卫星精密星历计算的时延理论值，对北斗GEO卫星CEI群时延和相时延结果进行评估。结果表明，相干测距模式下CEI群时延和相时延残差均值分别为0.47ns、0.08ns，标准差(3σ)分别4.2ns、0.13ns。该项研究验证了相干测距模式下CEI相时延解算的可行性，可为共位地球同步卫星精密相对定位、月球探测器CEI测量提供技术参考。     

深空测控新技术研究进展

测控系统是航天工程不可或缺的重要组成部分,其导航通信能力在深空探测任务中尤为重要。深空探测任务远距离、长延迟、弱信号、易中断条件下高精度导航测量和高速可靠数据传输始终是深空测控技术需要重点解决的问题。围绕这些问题重点介绍了在天线组阵、再生伪码测距、连接端站干涉测量、相位参考干涉测量和容延迟网络等一系列新技术方面开展的研究工作和部分成果,可以看到,这些成果的应用将丰富深空测控技术手段,在未来更复杂、更遥远的深空探测任务中将会发挥重要作用。