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R.G. Schnurr, M.A. Greenhouse, R. Whitley, K.J. Kalinowski, B.W. Love, J.W. Travis, M.M. Jurotich (NASA GSFC), K.S. Long (STSCI)
System
The Data system for the Next Generation Space Telescope (NGST) Integrated Science Module (ISIM) is the primary data interface between the spacecraft, telescope, and science instrument systems. This poster includes block diagrams of the ISIM data system and its components derived during the pre-phase A Yardstick feasibility study. The poster details the hardware and software components used to acquire and process science data for the Yardstick instrument compliment, and depicts the baseline external interfaces to science instruments and other systems. This baseline data system is a fully redundant, high performance computing system. Each redundant computer contains three 150 MHz power PC processors. All processors execute a commercially available real time multi-tasking operating system supporting, preemptive multi-tasking, file management and network interfaces. These six processors in the system are networked together. The spacecraft interface baseline is an extension of the network, which links the six processors. The final selection for Processor busses, processor chips, network interfaces, and high-speed data interfaces will be made during mid 2002.
Software task diagrams with data flow paths are presented to summarize all aspects of the system. This software configures the instruments for an observing mode, using an event-based scheduler included in the ISIM Data system software. The software also operates custom Field Programmable Gate Array hardware to acquire and process the data from the three Yardstick science instruments, which are operated independently. The software also operates hardware in the ISIM data processor to compress and format the science data into observation file records. These observation files are transferred to the spacecraft data system using a network interface. Non real time software in the ISIM data system computes primary mirror figure and focus commands required to tune the telescope for optimal performance. The ISIM data system software also delivers a real-time fine guidance command derived from processed wide field camera data.
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