ABSTRACT

Zero Doppler centroid imaging is of great significance in synthetic aperture radar interferometry (InSAR). Because the moon’s orbit is elliptical and its orientation cannot be changed artificially, the zero Doppler centroid of lunar-based synthetic aperture radar (LB-SAR) is not steerable and will vary with lunar rotation and SAR system’s position on lunar surface. Therefore, the distribution of zero Doppler centroid of LB-SAR will provide an important reference for observation model design of LB-SAR/InSAR. In this letter, we propose a calculation method of zero Doppler centroid by using the Jet Propulsion Laboratory (JPL)/NASA development ephemeris 430 (DE430), investigate the spatio-temporal distribution of the zero-Doppler line (ZDL). The results show that 1) the position of zero Doppler centroid deviates from the central meridian of a sublunar point from 0° to 45° within a sidereal month, 2) the maximum longitude difference of ZDLs corresponding to different SAR system’s position on lunar surface is about 60 km, and 3) the greatest effect of topography on ZDL estimation is about 1.1 km. The proposed calculation method of ZDL and results analysis are of instructive significance to the site selection and attitude control of lunar-based radar in the design of LB-SAR/InSAR.

摘要

零多普勒质心成像在合成孔径雷达干涉测量（InSAR）中具有重要意义。由于月球的轨道是椭圆形的，并且无法人为改变其方向，因此基于月球的合成孔径雷达（LB-SAR）的零多普勒质心无法操纵，并且会随着月球旋转和SAR系统在月球表面上的位置而变化。因此，LB-SAR的零多普勒质心分布将为LB-SAR / InSAR的观测模型设计提供重要参考。在这封信中，我们提出了一种使用喷气推进实验室（JPL）/ NASA发展星历表430（DE430）的零多普勒质心的计算方法，研究了零多普勒谱线（ZDL）的时空分布。结果表明：1）在恒星月内零多普勒质心的位置偏离月下亚点的中央子午线从0°到45°； 2）对应于不同SAR系统在月球表面位置的ZDL的最大经度差为约60公里，以及3）地形对ZDL估算的最大影响约为1.1公里。提出的ZDL计算方法和结果分析对LB-SAR / InSAR设计中的月球雷达选址和姿态控制具有指导意义。