空间引力波探测关键技术预先研究

Gravitational waves detection is a significant scientific research, not only for testing Einstein's General Relativity but also for opening another window to explore the origin and structure of universe. Compared with the ground-based gravitational waves detection, the spaceborne gravitational waves detection aims at detecting low-frequency waves that are generated by more interesting astrophysical phenomena. However, it is an extremely challenging mission, and we have almost no research experience in this field in China. From this aspect, the gravitational waves detection is meaningful and also a strong driving force to push the development of high-end space technologies. This project is focused on the spaceborne gravitational waves detection mission proposed in China that had been discussed for a certain time period, meanwhile, refering to the LISA (Laser Interferometer Space Antenna) project developed by USA and Europe. Based on the research experience and progresses on precision inertial sensor and intersatellite laser ranging achieved by our research group in the past years, we will further explore the technical scheme of spaceborne gravitational waves detection, develop high-precision multi-degree-of-freedom torsion pendulum for research on inertial sensing and its ground-based testing. Moreover, we will develop the key technologies of intersatellite laser ranging, especially for the case of long baseline with ultra-high precision of laser ranging based on current 10m prototype experiment, and corresponding ground-based testing. The final science goal is to build the solid foundation of spaceborne gravitational waves detection mission in China that is expected to be lunched in the future.

引力波探测具有重大科学意义，不仅直接检验爱因斯坦广义相对论，也将提供另一手段和窗口来研究宇宙起源和结构。相对地面引力波探测而言，空间探测频带低，波源多，对应更丰富的天体物理现象，但技术难度大，因此，相对我国引力波探测几乎空白的现状而言，致力于发展空间引力波探测不仅科学意义特别重大，而且势必将导致发展一批高新空间技术。本项目将针对我国科学家最近多次论证提出的空间引力波探测计划，参考欧美合作的空间引力波天线LISA计划的研究进展，在项目组多年来惯性传感器和星间激光测距研究基础上，进一步深入论证空间引力波探测的总体技术方案，同时研制高精度多级扭摆系统开展惯性传感器技术攻关、地面测试和验证工作，在已有10m地面星间激光测距研究平台基础上开展等效距离更远、精度更高的星间激光测距关键技术攻关、地面测试和验证工作。最终，为我国空间引力波探测总体技术方案确定和项目的进一步实施奠定厚实基础。

根据计划书要求，本项目主要面向空间引力波探测任务中亟待解决的若干关键技术展开理论和实验研究–主要包括高精度空间惯性传感器设计及其性能验证、星间距离的激光高精度干涉测量技术。项目已遵照计划书有序推进，各单元技术的进展良好，符合甚至超出计划书要求，本资助支持下取得的进展对于推进我国自主开展的空间引力波探测项目具有重要意义。.本项目针对空间引力波探测任务专门设计了高精度惯性传感器，理论分析了其噪声特性，重点发展了基于扭摆的隔振和性能测试等相关地面验证技术，完成了测量分辨率达到10-14m/s2/Hz1/2@1mHz量级的地面测试系统的研制和测试，传感器电路噪声达到了1.6×10-7pF/ Hz1/2@0.1Hz、检验质量净电荷探测与管理分辨率达到了1.4×10-14 C/Hz1/2@1mHz；设计并建设了星间激光干涉测距地面性能测试验证系统，在该系统上重点实验研究了星载超稳主激光系统、超稳干涉仪光学平台、激光指向控制、高精度相位计，以及弱光锁相等硬件单元，其中激光干涉仪分辨率在0.4Hz频率处达到了1pm/Hz1/2量级，相位计分辨率达到了10-6rad/Hz1/2@0.1Hz，激光指向控制精度达到了2×10-7rad/Hz1/2@0.1Hz；为了研究和验证检验质量表面作为反光镜进行激光干涉测量时两个子系统间的耦合，设计并建设了地面物理仿真系统并进行了实验研究。