A live web broadcast showed the first stage of the rocket touching down vertically on a floating sea platform.
The rocket lifted off from Florida`s Cape Canaveral Air Force Station at 1.21 a.m. local time (0521 UTC). The lower segment of the rocket broke away less than three minutes later, landing on a platform in the Atlantic Ocean, some 400 miles (650 kilometers) from the launch spot.
SpaceX owner Elon Musk was unable to contain his excitement on social media.
"The Falcon has landed," said one of the landing commentators.
The company, which successfully achieved a first landing at sea in April, had played down expectations about the latest mission. The rocket`s controlled descent was conducted on a minimal amount of fuel, from a higher altitude than previously, having delivered the Japanese JCSAT-14 telecommunications satellite into orbit as part of its commercial mission.
SpaceX says the reusability of its rockets is the key to making space launches cheaper and more accessible.
Dream of Red Planet
The launch was the fourth of more than a dozen flights scheduled this year, with SpaceX contracted to deliver satellites for a range of clients including NASA. Last week, the company won its first contract to launch a military satellite, breaking the monopoly of a company joint-owed by Lockheed Martin and Boeing.
SpaceX is the only company to so far recover a rocket after an orbital launch, having achieved its first landing - on solid ground - back in December.
The company hopes to begin delivering US astronauts to the International Space Station - using its Dragon capsules - by the end of next year. However, its ultimate goal is to send an unmanned spacecraft to Mars by 2018, with Musk aiming for a human mission in the 2030s.
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