JAPAN'S space agency launched its much-delayed lunar probe today, beginning what it calls the largest mission to the moon since the US Apollo flight.

The rocket carrying the three-tonne SELENE orbiter took off into blue skies over the tiny island of Tanegashima, about 1,000 km south of Tokyo, at 10:31am today.

The long-delayed lunar explorer is scheduled to separate from the rocket about 45 minutes after lift off before orbiting the Earth twice and then travelling 380,000 km to the moon.

"The first-stage engine is working normally," the space agency's launch commentator said in a live broadcast of the launch on the Japanese space agency's Website.

Japan's scientists say the 55 billion yen (US$479.2 million) launch of SELENE, which stands for Selenological and Engineering Explorer, is the world's most technically complex mission to the moon since the US Apollo programme decades ago.

The mission, nicknamed Kaguya after a moon princess in an ancient Japanese fairy-tale, consists of a main orbiter and two baby satellites equipped with 14 observation instruments designed to examine surface terrain, gravity and other lunar features for clues on the origin and evolution of the moon.

The Japan Aerospace Exploration Agency (JAXA) has said it hopes to send astronauts to the moon by 2025, although Japan has not yet attempted manned space flight.

Selene also carries a high-definition television camera to shoot the Earth "rising" from the Moon's horizon, footage of which will be sent back to Earth. Selene will orbit the moon for about a year until it runs out of fuel.

The launch is about four years behind schedule due to rocket failures and technical glitches.

China plans to launch a lunar orbiter called Chang'e One in the second half of this year to take 3D images, and it aims to land an unmanned vehicle on the moon by 2010.

India is planning its first unmanned mission to orbit the moon in 2008, powered by a locally built rocket. It is also discussing sending a person to the moon by 2020.

The United States plans to launch a lunar orbiter next year.

(Agencies)