Space: Hoofs of Hydrogen

After five years and $325 million worth of frustration, a snow-white Centaur rocket flashed its hoofs high over Cape Kennedy last week and galloped into orbit. As its Atlas booster fell away, the Centaur's own nozzles bloomed with a blue, barely visible flame: the high-energy signature of burning hydrogen.

Up by the Bootstraps. Designed to hurl more than a ton of instrument payloads all the way to the moon, the 28½-ft. Centaur generates 30,000 Ibs. of thrust with its two restartable Pratt & Whitney engines. The hydrogen fuel they burn has been the...