Space Station-Era Ground Data Handling

Abstract

To support the Space Station-era space data flows through ground facilities, plans to handle peak return link data rates ranging from 300 Mbps to 1200 Mbps and average rates growing from 50 Mbps to hundreds of Mbps are being made. These numbers represent orders of magnitude greater rates than are handled today. Simply relaying the data to destinations, however, is not sufficient (nor so straightforward). Because of multiplexing of data, on-board tape recording and playback, noise, and other problems with the space-to-ground link, these data must be reassembled for users into the sequences in which the data were originally produced on-board with error checking, retransmission, correction, or flagging as required to eliminate or tag erroneous data. In the past these services (called Level Zero Processing) have required large operations staffs and have involved delays of 30 to 90 days for final formatting and shipping of data tapes to users. NASA's expectations for improving the SS-era operations depend on providing time ordered, error corrected or flagged data sets with no redundant data packets within 24 hours of receipt on the ground with backup of data for one week. These data sets would be transmitted electronically to data centers for higher level processing and would require no more operations personnel than are required today for systems processing less than 1/100 of the data. To support a variety of user requirements, some of the data will be provided in real time or, if recorded on-board, as priority playback data. Other data sets will be created from on-board system engineering or housekeeping data combined with attitude, position, and time parameters into ancillary data packets. On the ground enhancement of the on-board ancillary data packets will provide standard calibrations and transformations not available on-board. Remote access to an interactive ancillary database will allow users to select and withdraw specified parameters based on user-defined criteria. The collection of these services is referred to as ground data handling and will be a critical component of the Space Station-era ground data operations and mission management system under development at Goddard Space Flight Center for NASA institutional support of Space Station-compatible missions. Challenges represented by this need for more ground processing capability include: * High speed, high rate multipath processors capable of continuous, real-time operation. * High volume data storage systems with high rate data ingest, rapid access to separate segments of data sets, and high rate data output. * Sophisticated information and system management services to provide system configuration monitoring and control, user support, and minimal human interaction. * Interactive database structures with traceable parameter updating and self-identified, standard data set formatting.