APOD mission status and preliminary results

• Published in: Science China. Earth sciences Vol. 63; no. 2; pp. 257 - 266
• Main Authors: Tang, Geshi, Li, Xie, Cao, Jianfeng, Liu, Shushi, Chen, Guangming, Man, Haijun, Zhang, Xiaomin, Shi, Sihan, Sun, Ji, Li, Yongping, Calabia, Andres
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.02.2020; Springer Nature B.V
• Subjects: Accuracy; Astronomical instruments; Atmospheric density; Chinese space program; Circular orbits; Cubesat; Data assimilation; Data collection; Detection; Earth and Environmental Science; Earth Sciences; Global navigation satellite system; Global positioning systems; GPS; Instruments; Interferometry; Lasers; Mechanical systems; Microelectromechanical systems; Navigation; Navigation satellites; Navigation systems; Navigational satellites; Orbit determination; Products; Research Paper; Satellite laser ranging; Satellite navigation systems; Satellites; Superhigh frequencies; Upper atmosphere; Upper atmosphere variations; Very long base interferometry; Low Earth orbit (LEO); Atmospheric density; Precise orbit determination (POD)
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-018-9362-6

On September 20th, 2015, twenty satellites were successfully deployed into a near-polar circular orbit at 520 km altitude by the Chinese CZ-6 test rocket, which was launched from the TaiYuan Satellite Launch Center. Among these satellites, a set of 4 CubeSats conform the atmospheric density detection and precise orbit determination (APOD) mission, which is projected for atmospheric density estimation from in-situ detection and precise orbit products. The APOD satellites are manufactured by China Spacesat Co. Ltd. and the payload instruments include an atmospheric density detector (ADD), a dual-frequency dual-mode global navigation satellite system (GNSS) receiver (GPS and Beidou), a satellite laser ranging (SLR) reflector, and an S/X-band very long baseline interferometry (VLBI) beacon. In this paper, we compare the GNSS precise orbit products with co-located SLR observations, and the 3D orbit accuracy shows better than 10 cm RMS. These results reveal the great potential of the onboard micro-electro-mechanical system (MEMS) GNSS receiver. After calibrating ADD density estimates with precise orbit products, the accuracy of our density products can reach about 10% with respect to the background density. Density estimates from APOD are of a great importance for scientific studies on upper atmosphere variations and useful for model data assimilation.