The Delta IV Heavy - the US military's biggest satellite launcher - has flown for only the second time.
The huge rocket lifted off from Cape Canaveral in Florida and successfully placed a spy spacecraft in orbit.
The 2.3-tonne Defense Support Program (DPS) satellite will monitor missile launches and gather intelligence.
The Delta IV Heavy first flew in 2004. Back then, manufacturer Boeing touted the behemoth as a possible astronaut launcher for use beyond the shuttle.
In the end, the US space agency decided to go with the new Ares rocket system for its post-shuttle programme.
The more than 70m-tall (230ft) Delta got away from its pad at 2050 EST on Saturday (0150 GMT, Sunday). It was described as the most spectacular night launch of an all-liquid fuelled booster since Apollo 17 in December 1972.
The rocket features three core boosters strapped side by side. Each has a Rocketdyne-built RS-68 engine, which burns a tonne of propellant every second and produces 2,900 kiloNewtons (650,000lbs) of thrust at lift-off.
The Apollo Moon rockets, by comparison, could produce more than three times the thrust of the Delta.
The Delta IV heavy can put up to 13 tonnes in a geostationary transfer orbit (GTO). It does not operate in the commercial market. The leader in that field is the European Ariane 5 ECA which can loft up to 10 tonnes to GTO. ( BBC )