LOS ANGELES - An Internet entrepreneur's latest effort to make space launch more affordable paid off Sunday when his commercial rocket, carrying a dummy payload, was lofted into orbit from the South Pacific.

It was the fourth attempt by Space Exploration Technologies, or SpaceX, to launch its two-stage Falcon 1 rocket into orbit.

"Fourth time's a charm," said Elon Musk, the multimillionaire who started up SpaceX after making his fortune as the co-founder of PayPal Inc., the electronic payment system.

The rocket carried a 165-kilogram dummy payload designed and built by SpaceX for the launch.

"This really means a lot," Musk told a crowd of whooping employees.

"There's only a handful of countries on Earth that have done this. It's usually a country thing, not a company thing."

"We did it."

Musk pledged to continue putting rockets into orbit, saying the company has resolved design issues that plagued previous attempts.

Last month, SpaceX lost three government satellites and human ashes, including the remains of astronaut Gordon Cooper and "Star Trek" actor James Doohan after its third rocket was lost en route to space. The company blamed a timing error for the failure that caused the rocket's first stage to bump into the second stage after separation.

SpaceX's maiden launch in 2006 failed because of a fuel-line leak. Last year, another rocket reached about 300 kilometres above Earth but its second stage prematurely shut off.

Falcon 1, a 20-metre-long rocket powered by liquid oxygen and kerosene, is the first in a family of low-cost launch vehicles priced at $7.9 million each.

Besides the Falcon 1, SpaceX is developing for NASA a larger launch vehicle, Falcon 9, capable of flying to the international space station when the current space shuttle fleet retires in 2010.