(25 Aug 1997) Natural Sound NASA's latest and cheapest space mission got off to a good start on Monday as a robotic explorer lifted off from Earth on a mission to study the sun. The Advanced Composition Explorer - known as ACE - will spend five years studying solar phenomena and the makeup of particles in space. The lift-off was one day late, after a pair of shrimp boats strayed into NASA's off-shore danger zone. But Monday's launch went without a hitch. All those left on Earth had the added