Space Microdatacenters

Earth observation (EO) has been a key task for satellites since the first time a satellite was put into space. The temporal and spatial resolution at which EO satellites take pictures has been increasing to support space-based applications, but this increases the amount of data each satellite generates. We observe that future EO satellites will generate so much data that this data cannot be transmitted to Earth due to the limited capacity of communication that exists between space and Earth. We show that conventional data reduction techniques such as compression [126] and early discard [41] do not solve this problem, nor does a direct enhancement of today's RF-based infrastructure [133, 153] for space-Earth communication. We explore an unorthodox solution instead - moving to space the computation that would have happened on the ground. This alleviates the need for data transfer to Earth. We analyze ten non-longitudinal RGB and hyperspectral image processing Earth observation applications for their computation and power requirements and discover that these requirements cannot be met by the small satellites that dominate today's EO missions. We make a case for space microdatacenters - large computational satellites whose primary task is to support in-space computation of EO data. We show that one 4KW space microdatacenter can support the computation need of a majority of applications, especially when used in conjunction with early discard. We do find, however, that communication between EO satellites and space microdatacenters becomes a bottleneck. We propose three space microdatacenter-communication co-design strategies - k - list-based network topology, microdatacenter splitting, and moving space microdatacenters to geostationary orbit - that alleviate the bottlenecks and enable effective usage of space microdatacenters.