US space firm Blue Origin conducted a successful fourth test Sunday of its reusable New Shepard rocket, which dropped back to Earth for a flawless upright landing seen on a live webcast.

Blue Origin, the space travel company founded by Internet entrepreneur Jeff Bezos, is trying to cut the costs of space travel by developing reusable rockets to boost manned capsules into suborbital space.

"Careful engineering plus of course ... the lucky boots, successful mission," Bezos quipped in a Tweet with a photo of his cowboy boots propped up on a desk.

The rocket landed at the Texas launch site at 9:44 am local time (1444 GMT), followed one second later by the capsule, which lofted back to Earth under parachutes.

"Amazing," said the announcer at Blue Origin's mission control. "Another picture perfect landing for the New Shepard rocket booster."

The rocket rose to 331,500 feet (100,000 meters), clearing the boundary between the Earth's atmosphere and space and releasing the capsule before dropping back for the controlled landing.

It reignited its engines at 5,000 feet, braking its descent to a speed of five miles per hour and then deploying its landing gear.

It was the fourth time the rocket has successfully landed upright after soaring into space.

The feat was first accomplished in November, and repeated in test launches in January and February.

One of the main objectives of this launch was to see whether the capsule could still land safely if one of its three strings of parachutes failed.

After the two parachutes deployed, the capsule could be seen rocking like a bell as it came down.

A larger chute was released seconds before the capsule landed, stabilizing it. A second before touchdown, rocket thrusters on the capsule were activated to cushion the landing.

Blue Origin's long-term goal is to send people into space, using reusable rockets.

Its breakthroughs and parallel efforts by rival Internet mogul Elon Musk's SpaceX open up the potential for cutting costs for space travel and making rockets as reusable as airplanes.