同波束VLBI技术在深空探测器测定轨中的应用

Applications of Same-Beam VLBI Technology in Orbit Determination of Deep Space Satellites

同波束VLBI技术即用射电望远镜的主波束同时接收两个探测器发送的信号,得到两个探测器信号的相关相位并在探测器间进行差分,去掉电离层、大气及观测装置的绝大部分影响,得到超高精度的差分相时延。差分相时延数据能准确反映两个探测器相对位置及其变化,可用来提高两个探测器的绝对和相对定轨定位精度。对同波束VLBI技术的基本原理及其在国内外深空探测器测定轨中的应用进行综述和展望。比如,我们利用同波束VLBI技术把嫦娥三号巡视器相对定位精度提高至1米,并有望把嫦娥五号轨道器和上升器的定轨精度提高至10米量级,把火星环绕器定轨精度和火星车定位精度提高至数百米等。

Same-beam VLBI technique is to use radio telescope main beam to receive signals from two spacecrafts, and calculate differential correlation phase to get rid of main influence of the ionosphere, atmosphere and devices, obtain high precision differential phase delay. Differential phase delay data accurately reflect relative position of two spacecrafts, which can be used to improve absolute and relative orbit determination precision. In this paper, the basic principle of the same-beam VLBI technique and its applications in orbit determination of deep spacecrafts are summarized. For example, using the same-beam VLBI technique, the relative positioning accuracy of ChangE-3 rover is up to lm, the orbit determination precision should be up to 10m for ChangE-5 returner and orbiter, and the accuracy of orbit determination of a Mars orbiter and a rover position can be up to several hundred meters.