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At seven metres high and four wide, with a launch weight of 5,600kg, the Cassini mission to Saturn is the largest planetary mission to date. Blasting off in 1997, it arrived at Saturn in 2004 and continues to observe the planet, its rings and moons, with mission-end planned for 2017.
Its 12 instrumentation packages contain many processors, but the core guidance and control is provided by dual Harris (now Intersil) RTX 2010RH processors running at six million instructions a second, 192kB of radiation-hardened static RAM (SRAM), 8 or 4kB of ROM, and 64kB radiation-hardened electrically erasable ROM (EEPROM, a precursor to flash). There's more memory on a support board — 832kB SRAM and 64kB EEPROM.
These systems are most notable for being hardware-implemented Forth systems — Forth being an obscure programming language initially designed to control radio telescopes with a small but fanatical following among technical programmers.