SpaceX boss Elon Musk hailed the breakthrough landing of its rocket booster at sea on 8 April, during a post-launch news conference at the Kennedy Space Center. A SpaceX Falcon 9 rocket blasted off from Florida during a cargo run for the International Space Station and its reusable main-stage booster landed on an ocean platform in a dramatic spaceflight first.

"I think this is a really good milestone for the future of space flight," said Musk. "I think it's another step towards the stars. In order for us to really open up access to space, we've got to achieve full and rapid reusability," he added.

The liftoff at 4.43pm local time from Cape Canaveral marked the resumption of resupply flights by privately owned Space Exploration Technologies for Nasa following a launch accident in June 2015 that destroyed a different cargo payload for the space station. About 2.5 minutes after the launch, the main part of the 23-story tall, two-stage SpaceX rocket separated, turned around and headed toward a landing platform floating in the Atlantic about 185 miles northeast of Cape Canaveral.

A live video feed broadcast on Nasa television showed the rocket booster, its four landing legs extended, descending over the ocean before settling itself upright on the platform, roughly eight minutes after launch.

Four previous at-sea landing attempts had failed. But a Falcon 9 main-stage rocket achieved a successful ground-based touchdown in December, the first ever during an actual commercial space mission. The feat marked yet another major milestone in the quest by high-tech entrepreneur Musk, founder and chief executive of the private launch service, to develop a cheap, reusable launch vehicle.

Asked how he felt as he watched the rocket booster land, Musk recreated the moment and hugged SpaceX Vice President of Flight Reliability Hans Koenigsmann. The rocket's cargo ship, dubbed Dragon, is due to arrive at the International Space Station on 10 April.