SpaceShipOne, a rocket plane developed in the United States, launched into aviation history Monday after accomplishing the world's first privately-funded flight to leave the earth's atmosphere.

The three-ton spaceship touched down safely at an airport in Mojave desert, California, at 11:15 ET (1515 GMT), following a journey that lasted about 90 minutes.

"It looks great," said Burt Rutan, chief of Scaled Composites, a Mojave-based company which built the spaceship.

SpaceShipOne was first lifted off by a jet-powered carrier aircraft named White Knight to approximately 15 kilometers and then released from the mother plane into a few seconds of glide.

Mike Melvill, the spacecraft's 62-year-old solo pilot, then fired the rocket motor for about 80 seconds, accelerating the vehicle to three times the speed of sound in a vertical climb into the outer space.

After re-entering the earth's atmosphere, the spacecraft glided for a landing on the same runway from which it took off.

The spaceship is expected to reach a peak height of 62 miles (100 kilometers). The exact altitude it achieved was to be confirmed later by radar.

The success of SpaceShipOne made Rutan and his team at Scaled Composites the most promising so far to win the 10 million-dollar Ansari X Prize, an international competition to create a reusable aircraft that can launch three people into space, return them safely home, then repeat the feat within two weeks with the same vehicle.

While Monday's flight involved only one pilot, Scaled Composites has said that based on the successful attempt, SpaceShipOne will later compete for the Ansari X Prize, which has attracted more than 20 teams around the world.

SpaceShipOne's maiden space flight "will demonstrate that the space frontier is finally open to private enterprise," the company said in a statement.

"Without the entrepreneur approach, space access would continue to be out of reach for ordinary citizens," said Rutan, who made news in 1986 by developing the Voyager, the only aircraft to fly nonstop around the world without refueling.

"SpaceShipOne flights will change all that and encourage others to usher in a new, low-cost era in space travel," he said.

Paul G. Allen, the billionaire co-founder of software giant Microsoft, is the sole sponsor of SpaceShipOne. He reportedly invested more than 20 million US dollars in the program.