Number 343 (Story #2), October 24, 1997 by Phillip F. Schewe and Ben Stein THE CASSINI/HUYGENS SPACECRAFT, the heaviest planetary probe ever built (4685 pounds), was launched recently. Its destination is Saturn, where in July 2004 it will study the planet while the detachable Huygens module will settle onto the surface of Titan, Saturn's giant moon, for closer inspection of its intriguing nitrogen/methane atmosphere. Cassini's takeoff was marked by controversy over the potential dangers posed by the cargo of plutonium needed for powering the craft in Saturn orbit. As with the Galileo craft sent to Jupiter years ago, Cassini must pick up momentum for the outward trip by first turning inward to Venus (twice) and Earth itself for gravity assistance.