SUMMARY

The GRACE and GRACE-FO missions have been observing time variations of the Earth's gravity field for more than 15 yr. For a possible successor mission, the need to continue mass change observations have to be balanced with the ambition for monitoring capabilities with an enhanced spatial and temporal resolution that will enable improved scientific results and will serve operational services and applications. Various study groups performed individual simulations to analyse different aspects of possible NGGMs from a scientific and technical point of view. As these studies are not directly comparable due to different assumptions regarding mission design and instrumentation, the goal of this paper is to systematically analyse and quantify the key mission parameters (number of satellite pairs, orbit altitude, sensors) and the impact of various error sources (AO, OT models, post-processing) in a consistent simulation environment. Our study demonstrates that a single-pair mission with laser interferometry in a low orbit with a drag compensation system would be the only possibility within the single-pair options to increase the performance compared to the GRACE/GRACE-FO. Tailored post-processing is not able to achieve the same performance as a double-pair mission without post-processing. Also, such a mission concept does not solve the problems of temporal aliasing due to observation geometry. In contrast, double-pair concepts have the potential to retrieve the full AOHIS signal and in some cases even double the performance to the comparable single-pair scenario. When combining a double-pair with laser interferometry and an improved accelerometer, the sensor noise is, apart from the ocean tide modelling errors, one of the limiting factors. Therefore, the next big step for observing the gravity field globally with a satellite mission can only be taken by launching a double pair mission. With this quantification of key architecture features of a future satellite gravity mission, the study aims to improve the available information to allow for an informed decision making and give an indication of priority for the different mission concepts.

中文翻译：

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一致量化关键任务设计参数对下一代重力任务性能的影响

概要

GRACE和GRACE-FO任务已经观测了地球重力场的时间变化超过15年。对于可能的后续任务，必须继续进行大规模变化观测，同时要兼顾监视能力和增强时空分辨率的野心，以实现更好的科学成果并为运营服务和应用服务。各个研究小组进行了单独的模拟，以从科学和技术的角度分析可能的NGGM的不同方面。由于这些研究由于任务设计和仪器的假设不同而无法直接比较，因此本文的目的是系统地分析和量化关键任务参数（卫星对数，轨道高度，传感器）以及在一致的仿真环境中各种错误源（AO，OT模型，后处理）的影响。我们的研究表明，与GRACE / GRACE-FO相比，在具有阻力补偿系统的低轨道上进行激光干涉测量的单对飞行任务是单对飞行任务中提高性能的唯一可能性。没有后处理的情况下，量身定制的后处理无法获得与双对任务相同的性能。而且，这样的任务概念不能解决由于观察几何形状而造成的时间混叠的问题。相比之下，双对概念有可能检索完整的AOHIS信号，在某些情况下甚至可以使性能达到可比单对方案的两倍。当双对激光干涉仪和改进的加速度计结合使用时，除了洋潮建模误差外，传感器噪声也是限制因素之一。因此，要通过卫星任务在全球范围内观测重力场，下一步只有迈向双对飞行任务。通过对未来卫星重力飞行任务的关键架构特征进行量化，该研究旨在改善可用信息，以便做出明智的决策，并给出不同任务概念的优先级指示。