GEOSCAN: Global Earth Observation using Swarm of Coordinated Autonomous Nanosats

The climate crisis we are facing calls for significant improvements in our understanding of natural phenomena, with clouds being identified as a dominant source of uncertainty. To this end, the emerging field of 3D computed cloud tomography (CCT) aims to more precisely characterize clouds by utilizing multi-dimensional imaging to reconstruct their outer and inner structure. In this paper, we propose a future Earth observation mission concept, driven by the needs of CCT, that operates constellation of NanoSats to provide multi-angular, spectrally-resolved, spatial and temporal scientific measurements of natural atmospheric phenomena. Our proposed mission, GEOSCAN, will on-board active steering capability to rapidly reconfigure networked swarm of autonomous Nanosats to track evolving phenomena of interest, on-demand, in real-time. We present the structure of the GEOSCAN constellation and discuss details of the mission concept from both science and engineering perspectives. On the science side, we outline the types of remote Earth observation measurements that GEOSCAN enables beyond the state-of-the-art, and how such measurements translate to improvements in CCT that can lead to reduction in uncertainty of the global climate models (GCMs). From the engineering side, we investigate feasibility of the concept starting from hardware components of the NanoSat that form the basis of the constellation. In particular, we focus on the active steering capability of the GEOSCAN with algorithmic approaches that enable coordination from new software. We identify technology gaps that need to be bridged and discuss other aspects of the mission that require in-depth analysis to further mature the concept.

当前我们面临的气候危机，亟需深化对自然现象的认知，而云被认定为造成气候模拟不确定性的主要来源之一。为此，新兴的三维云计算机断层扫描（3D computed cloud tomography, CCT）领域旨在通过多维成像技术重建云的内外结构，从而更精准地刻画云的特性。本文基于三维云计算机断层扫描的需求，提出一项未来地球观测任务构想：通过部署纳卫星（NanoSat）星座，对自然大气现象开展多视角、光谱分辨、兼具时空维度的科学测量。本次提出的GEOSCAN任务将搭载星载主动操控能力，可按需实时快速重构自主纳卫星组网星群，以追踪实时演化的目标大气现象。本文阐述了GEOSCAN星座的架构，并从科学与工程双视角探讨了该任务构想的细节。在科学层面，本文梳理了GEOSCAN所能提供的、超越现有技术前沿的地球遥感观测类型，并阐述了此类测量如何推动三维云计算机断层扫描技术的性能提升，进而降低全球气候模式（global climate models, GCMs）的不确定性。在工程层面，本文从构成星座基础的纳卫星硬件组件出发，对该任务构想的可行性展开了研究。具体而言，本文重点探讨了GEOSCAN的主动操控能力，以及依托新型软件实现星群协同的算法方案；同时明确了当前仍需攻克的技术短板，并讨论了该任务构想中需开展深度分析以进一步完善的其他环节。