Communication support for future earth science space missions

摘要

The NASA Earth Science Enterprise's (ESE's) vision for the future involves a scenario where all Earth observing spacecraft form a distributed network to provide real-time multi-sensor information transfer to users on the ground. This scenario will require sensors and instruments on spacecraft to become addressable nodes in a communication network. These include missions consisting of single spacecraft to multiple spacecraft flying in formation, in clusters, or in constellations. The present labor-intensive, mission-specific techniques for processing and routing data do not scale well and will become prohibitively expensive. To enable this vision, there is a critical need for advanced communications and dynamic network connectivity to provide broad coverage and intelligent-based real-time data delivery to scientists. These new missions will introduce a number of complex routing, network control, scheduling, data management and communication problems that need to be studied in detail. We introduce the current state-of-the-art in space communications for ESE, discuss potential benefits of a Uniform Space Network infrastructure and list some specific challenges in areas such as routing, transport layer and multiple access in this environment. We address issues related to extending this network in space and typical communication requirements and topologies for Earth Science missions and present a dynamic routing algorithm, MDRSH, for dynamically directing traffic from mission spacecraft to ground facilities. We present a simulation framework for studying future space missions and for testing newly developed protocols in such missions. We also present a case study for optimizing data downloads for a typical future mission scenario.