The key issues of the conjunction of European and Chinese next-generation gravity missions for Earth's gravity field determination

中国、欧洲和美国已经制定了下一代重力任务的具体计划。它们主要基于类似于Grace和Grace-Follow的卫星串联对概念。以前的研究表明，当联合分析双对或多对概念时，单对概念可以取得显著的改进，这主要是因为它们具有更强的减少时间混叠效应的能力。在德国和中国项目合作伙伴的共同努力下，该提议的主要目标是为中国下一代重力任务(如天琴二号)和将由欧空局实施的欧洲NGGM设计一个最佳卫星星座。基于已知的天琴二号任务轨道和仪器性能的关键参数，当将这些任务视为星座时，优化主要是为了优化科学回报。此外，还应考虑到，美国国家航空航天局可能会实施第三对卫星，因此在理想情况下，三对卫星可以在不久的将来并行飞行。应针对这一非常具体的设置进行方法开发，并对重力场应用的附加值进行分析和量化。该项目的成果将为共同开发未来的空间基础设施铺平道路，将支持国际空间机构的飞行任务规划和设计，并将量化这种关于非零增长空间机制的国际合作对若干具有社会意义的地球科学应用的惠益。

Concrete plans for next-generation gravity missions have been established in China, Europe and also US. They are mainly based on satellite in-line pair concepts similar to GRACE and GRACE-Follow On. In previous studies it could be shown that significant improvements over single-pairs can be achieved when jointly analysing double-pair or multi-pair concepts, which is mainly due to their enhanced capabilities to reduce temporal aliasing effects. In a joint and concerted effort of German and Chinese project partners, the main objective of this proposal is to design an optimum satellite constellation of Chinese next-generation gravity missions such as TianQin-2, and a European NGGM to be implemented by ESA. Based on known key parameters of the TianQin-2 mission regarding orbits and instrument performance, the optimization shall mainly be done to optimize the science return when considering these missions as a constellation. Additionally it shall be taken into account, that a third satellite pair might be implemented by NASA, so in the ideal case three satellite pairs could fly in parallel in the near future. Methodology developments tailored to this very concrete set-up shall be performed, and the added value for gravity field applications shall be analyzed and quantified. Results of the project will pave the way towards a joint exploitation of future space infrastructure, will support the mission planning and design of international space agencies, and will quantify the benefit of such an international cooperation on NGGMs for several geoscientific applications with societal relevance.