Needs for communications and onboard processing in the vision era

The NASA New Millennium Program (NMP), in conjunction with the Earth Science Enterprise Technology Office, has examined the capability needs of future NASA Earth Science missions and defined a set of high priority technologies that offer broad benefits to future missions, which would benefit from validation in space before their use in a science mission. In the area of spacecraft communications, the need for high and ultra-high data rates is driving development of communications technologies. This paper describes the current vision and roadmaps of the NMP for the technology needed to support ultra-high data rate downlink to Earth. Hyperspectral land imaging, radar imaging and multi-instrument platforms represent the most demanding classes of instruments in which large data flows place limitations upon the performance of the instrument and systems. The existing and prospective data distribution (DD) modes employ various types of links, such as DD from low-Earth-orbit (LEO) spacecraft direct to the ground, DD from geosynchronous (GEO) spacecraft, LEO to GEO relays, multi-spacecraft links, and sensor webs. Depending on the type of link, the current data rate requirements vary from 2 Mbps (LEO to GEO relay) to 150 Mbps (DD from LEO spacecraft). It is expected that in the 20-year timeframe, the link data rates may increase to 100 Gbps. To ensure such capabilities, the aggressive development of communication technologies in the optical frequency region is necessary. Current technology readiness levels (TRL) of the technology components for the space segment of communications hardware varies from 3 (proof of concept) to 5 (validation in relevant environment). Development of onboard processing represents another area driven by increasing data rates of spaceborne experiments. The technologies that need further development include data compression, event recognition and response, as well as specific hyperspectral and radar data processing. Aspects of onboard processing technologies requiring flight validation include: fault-tolerant computing and processor stability, autonomous event detection and response, situation-based data compression and processing. The required technology validation missions can be divided in two categories: hardware-related missions and softwar- e-related missions. Objectives of the first kind of missions include radiation-tolerant processors and radiation-tolerant package switching communications node/network interface. Objectives of the second kind of missions include autonomous spacecraft operations and payload (instrument-specific) system operations.