If successful, the "Muses-C" will be the first probe to make a two-way trip to an asteroid. A NASA probe collected data for two weeks from the surface of the Manhattan-sized asteroid Eros in 2001, but it was not designed to return with samples.
The unmanned Muses-C was launched Friday atop a $60 million M-5 rocket from the Kagoshima Space Center on the island of Kyushu in southern Japan.
The probe is to make three brief contacts with the tiny asteroid 1998 SF36, about 180 million miles away from Earth.
It's going to take the Muses-C about two years to get there, but the asteroid - only 2,300 feet long and 1,000 feet wide - is among the Earth's closest neighbors.
The plan is to gather surface samples from the asteroid in June 2005 and parachute them in a re-entry capsule that reaches the southern Australia town of Woomera two years later.
Muses-C will conduct a three-month survey of the asteroid from an altitude of about 12 miles and then move close enough to fire a small bullet into the asteroid and collect the ejected fragments.
The craft will bring back a gram or so of the football-shaped asteroid's surface, the first space rocks to be gathered since the U.S. Apollo lunar exploration program ended 30 years ago.
Japan's space agencies have recently had a series of successes, despite budget overruns and a major restructuring later this year.
In March, an H2-A rocket, Japan's main launch vehicle, put this country's first spy satellites into orbit. It was the fifth consecutive successful launch for the H2-A, which Japan hopes will one day compete in the commercial satellite launching business.
The Muses-C was launched atop the smaller M-5 rocket. Japan launched its first M-5 in 1997, and had three successful liftoffs in a row. But the failure of the fourth M-5 rocket to put a probe into orbit in February 2000 forced planners to postpone the Muses-C launch.
A failure in its altitude regulating system caused a further delay and swelling costs prompted NASA to shelve a project to build a tiny, wheeled robot for the probe.
To boost interest, the public was invited to submit names over the Internet to be sent into space with the probe - 877,490 were collected and have been etched on an aluminum-foil wrapper around a grapefruit-sized marker that will be dropped onto the asteroid's surface.
By Eric Talmadge