High-Accuracy determination of very long baseline interferometry phase delays and its applications in China's future missions

This paper reviews the methods of same-beam very long baseline interferometry (VLBI) observations and the estimation of high-accuracy phase delay. We report the observation results of the phase delay on the Shanghai-Urumqi baseline, with a measurement error as small as 0.0005m. We also describe the same-beam VLBI observation teechniques for the Chinese Yinghuo-1 and Russian Phobos-Grunt spacecrafts, and a new method to estimate phase delay. Prospective applications in China's future missions are surveyed.