NASA's Space Network Ground Segment Sustainment Project Preparing for the Future

摘要

NASA's Tracking and Data Relay Satellite System (TDRSS) ground terminals will be replaced in the 2015 timeframe. The existing terminals have been subject to many small scale upgrades and modifications since their last major refurbishment in 1994. The ground terminals, in conjunction with seven operational geosynchronous communication relay satellites, support over 20 customer spacecraft, including Terra, Hubble Space Telescope, the International Space Station and others. The terminal replacement effort, called the Space Network Ground Segment Sustainment (SGSS), will modernize the ground terminal communications infrastructure and provide new capabilities for customers. This paper describes the new architecture, some of the significant technology upgrades and the operations concepts that will enable TDRSS to provide additional services to more customers at lower cost. The SGSS will provide a flexible, extensible, scalable and sustainable ground segment that will: 1) maintain existing Space Network (SN) capabilities and interfaces; 2) accommodate new customers and capabilities, including higher data rate support and additional modulation and coding schemes; 3) reduce the effort required to maintain the ground terminals; 4) transition operations from the existing system to SGSS without disrupting services, and; 5) achieve a 99.99% operational availability for customer services. The SGSS will accomplish this by: 1) implementing an architecture using state-of-the-practice technology which enables low impact incremental upgrades; 2) simplifying the expansion process for adding ground and space assets; 3) incorporating commercial off-the-shelf (COTS) products to a very large extent, and; 4) maximizing equipment commonality. Some of the new and enhanced SGSS capabilities include: 1) the ability to easily add new transmit and receive waveforms; 2) early signal digitization for lossless signal distribution; 3) high speed digital packet switching; 4) new coding schemes, including low-density parity-check (LDPC) and turbo product codes (TPC); 5) Ka-band one-way tracking services, and; 6) data rate increases to 50Mbps for command and 1.2 Gbps for telemetry.