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High precision gravity observation is an important tool of seismological research and has played an important role in earthquake prediction in China in recent years. This paper first briefly introduces the development status and classification of gravity observation instruments, then compares the seismic gravity observations and researches for seismic events between China and Japan from the aspects of the scale of the seismic gravity observation network, the gravity data processing process and the interpretation of gravity observation results, and finally systematically analyzes the challenges faced by the gravity observation re⁃ search in China. The aim of this paper is to provide some reference and enlightenment for the follow-up work. [ABSTRACT FROM AUTHOR]

This paper mainly introduces the layout of mobile gravity monitoring network in China, and the gravity measurement data processing and extraction method of gravity precursor information. Mobile gravity monitoring results can reflects the image of dynamic evolution of regional gravity field and its tectonic activity characteristic. Based on a large number of observation data, the relationship between gravity variation and earthquake preparation is studied, and the ideas, ways and methods of earthquake prediction research are explored. The mid-term earthquake risk prediction research is carried out by using gravity observation data, and its results are used for earthquake consultation and annual earthquake trend prediction in time, which provide basises for the prediction of strong earthquakes and the delineation of annual dangerous areas in China. this paper points out the existing problems in mobile gravity monitoring in China, and puts forward the idea and thinking of using time-varying gravity monitoring data to promote seismic prediction research. [ABSTRACT FROM AUTHOR]

Objectives: With the development of deep-space technology of China, the Jupiter exploration program has been added into the schedule. The precise orbit determination (POD) and gravity field recovery play an important role in Jupiter exploration. Methods: This paper focuses on the precise orbit determination of Juno and low degree gravity field recovery of Jupiter. Firstly, the coordinate system and dynamics model of the Jupiter probe are given, and the Juno precision ephemeris of jet propulsion laboratory (JPL) is used for verification. Then, the deep-space Doppler measurement model is presented and the trajectory of Juno is calculated by using the tracking data. Results: The dynamical fitting position difference is on the order of 10 m, and the velocity difference is less than 6 mm/s. The difference with the reference orbit given by JPL is better than 1 kilometer. Conclusions: The simulation data is used to verify the reliability of gravity field solution, and the measured data near 4 perijove points of the Juno is used to calculate the gravity field coefficients of Jupiter, obtaining the gravity field zonal coefficients up to 8 degrees [ABSTRACT FROM AUTHOR]

Objectives: The Chinese Mars probe has been successfully launched and is currently orbiting Mars. This article analyzes several different satellite orbit characteristics in detail to find out the suitable orbits with stable operation characteristics. Methods: This paper uses the MAGREAS （Mars gravity recovery and analysis software/system） independently developed by Wuhan University to analyze the evolution of satellite orbits under different initial orbit heights, different initial orbital inclinations, different initial orbital eccentricities, and different orders of Martian gravitational field models. Then we make orbit predictions for the four situations.Results: The results show that satellite can run for nearly two years without any orbital adjustment. When the initial orbital inclination is 90°, it does not contribute to the running time of the satellite. In the calculation of orbital integration, the Martian gravity field model can be intercepted to 100 degrees without affecting the calculation accuracy.Conclusions: This paper has done a lot of orbit predictions based on different initial orbit elements, and analyzed the evolution characteristics of different satellite orbits. This research can provide a certain reference for China's Mars exploration project. [ABSTRACT FROM AUTHOR]