Development of a crosslink channel simulator

Distributed spacecraft missions are an integral part of current and future plans for NASA and other space agencies. Many of these multi-vehicle missions involve utilizing the array of spacecraft as a single, dispersed instrument requiring communication via crosslinks to achieve mission goals. NASA's Goddard Space Flight Center (GSFC) is developing the formation flying test bed (FFTB) to provide a hardware-in-the-loop simulation environment to support mission concept development and system trades with a primary focus on guidance, navigation, and control (GN&C) challenges associated with spacecraft formation flying. The goal of the FFTB is to reduce mission risk by assisting in mission planning and analysis, providing a technology development platform that allows algorithms to be developed for mission functions such as precision formation navigation and control and time synchronization. The FFTB provides a medium in which the various crosslink transponders being used in multi-vehicle missions can be integrated for development and test; an integral part of the FFTB is the crosslink channel simulator (CCS). The CCS is placed into the communications channel between the crosslinks under test, and is used to simulate on-mission effects to the communications channel such as vehicle maneuvers, relative vehicle motion, or antenna misalignment. The CCS is based on the Starlight/spl trade/ software programmable platform developed at the former general dynamics decision systems, which is part of a newly-integrated business unit now know as general dynamics CS systems (GDC4S), and provides the CCS with the ability to be modified on the fly to adapt to new crosslink formats or mission parameters. This paper briefly describes the formation flying test bed and its potential uses. It then provides detail on the current and future development of the crosslink channel simulator and its capabilities.