A spacecraft mass storage optical disk system

NASA (the US National Aeronautics and Space Administration) has established a program to develop a high-performance (high-rate, large-capacity) optical disk recorder. An expandable, adaptable system concept is proposed based on disk drive modules and a modular controller. Drive performance goals are ten gigabyte capacity, 300 megabit per second transfer rate, 10^-12 corrected bit error rate, and 150 millisecond access time. This performance is achieved by writing eight data tracks in parallel on both sides of a 14-inch optical disk using two independent heads. System goals are 160 gigabyte capacity, 1.2 gigabit per second data rate with concurrent input/output (I/O), 250 millisecond access time, and two- to five-year operating life on orbit. The system can be configured to meet various applications. This versatility is provided by the controller, which provides command processing, multiple drive synchronization, data buffering, basic file management, error processing, and status reporting