The European probe Giotto passes just 600 km from Halley’s Comet, at a staggering 68 km/sec. It manages to photograph the comet’s dark nucleus in incredible detail. It is also struck by two cometary grain impacts (likely much smaller than a millimeter, and weighing less than 0.4 grams), which are enough to rotate the entire probe, which weighs a staggering 500 kg!
