Technology drivers for the future of space-based science communications

This paper reviews an ongoing study, sponsored by NASA, to identify the technological developments required to create an advanced space communications network useful for science data collection. A methodology is developed to forecast technology needs out to 2020. The network model is that of an advanced, flexible communications infrastructure based on extending the mechanics of the terrestrial Internet to space. Such a network allows desk-top control of space-based science instruments and access to data. The logical network embodies open system concepts and employs data packet delivery methods. System architecture addresses gateways, routing, VPNs and security. It is applicable to both near-Earth and to deep-space activities and is coordinated with the science community. Options for communications links, both space-to-space and space-to-ground, are examined. On-board processing may be employed to reduce data exchange. Data compression is an option, but actual on-board processing is anticipated. There is a fundamental trade between computer processing and data pipeline size that drives the data rates. Based on a detailed analysis of payload constraints, the limitations on RF transmission data rates (maximum link capacity) are estimated for both space-to-space and space-to-ground segments. The role of laser communications is explored. The salient factors driving technology needs for each of the topics is extracted and included in representative technology roadmaps.