In an unpublicized launch lacking fanfare, an H-2A rocket successfully boosted Japan's most advanced spy satellite to orbit on Saturday from the country's island space center.

The 174-foot-tall launcher lifted off at 0121 GMT Saturday (8:21 p.m. EST Friday) from Launch Pad No. 1 at the Yoshinobu complex on the southern shore of Tanegashima Island. The rocket's launch occurred at 10:21 a.m. local time.

The two-stage rocket turned south from Tanegashima and jettisoned a pair of solid fuel-burning boosters two minutes into the flight. The hydrogen-fueled first and second stages propelled the top secret Information Gathering Satellite into a polar orbit about 15 minutes after leaving Earth.

Japanese government officials declared the launch a success, according to news reports.

The mission was shrouded in secrecy at the space center, which is operated by the Japan Aerospace Exploration Agency. The space agency released no information on the launch, and a JAXA web camera was turned away from the launch complex after the H-2A rocket rolled to the pad.

The supposed payload was a more than $500 million satellite outfitted with an optical camera and telescope to supply imagery to the Japanese government for intelligence, defense and civilian remote sensing applications. The spacecraft will become the fifth operational member of Japan's spy satellite fleet.

Two optical reconnaissance craft and two satellites with ground-mapping radars were deployed on previous launches. Radars in orbit can collect all-weather imagery during day and night passes.

Another set of spy satellites were lost in an H-2A launch failure in 2003, the only blemish in 16 flights of Japan's workhorse launcher.

Japan established the space-based reconnaissance program after North Korea fired a test missile over Japanese territory in 1998. The country's spy satellites have become increasingly more advanced since then, but officials have provided no official specifications on the satellite launched Saturday.

Another North Korean missile test over Japan in April prompted further consideration of an early warning satellite with an infrared sensor dedicated to detecting missile launches.

Saturday's flight was the third Japanese space launch of the year, including the maiden launch of the beefed up H-2B rocket with the HTV cargo ship for the International Space Station.