TOKYO (AP)--Japan's space agency plans to launch an arrow-shaped airplane at twice the speed of sound high over the Australian outback as early as next month in a crucial test of the country's push to develop a supersonic successor to the retired Concorde.

The test follows a three-year hiatus since the first experimental flight of the unmanned aircraft, dubbed the next-generation supersonic transport, prematurely separated from its booster rocket and crashed into the desert.

"We've made some improvements so that won't happen again," Takaaki Akuto, a spokesman for the Japan Aerospace Exploration Agency, said Tuesday in Tokyo. "This is a pretty important test."

A successful mission will pave the way for additional experiments as JAXA aims to develop a plane that can carry 300 passengers at Mach 2, or twice the speed of sound, making the run from Tokyo to Los Angeles in about four hours. It will also underpin a June agreement between Japan and France to jointly research such a plane over the next three years.

JAXA will launch the experimental craft, piggybacked on a rocket, at Australia's Woomera test range between Sept. 15 and Oct. 15, Akuto said. The rocket will carry the plane to an altitude of 12.4 miles before releasing it at a speed of Mach 2 to collect information about the plane's aerodynamics. The craft will float back to earth by parachute after the 15 minute flight.

If the 1.1 billion yen ($10 million) experiment works, Japan's space agency plans to follow up with similar tests of a jet-powered craft, Kyodo News Agency reported.

Japanese and French defense contractors and engineering companies, including Mitsubishi Heavy Industries Ltd. and Airbus parent European Aeronautic Defence and Space Co., agreed earlier this summer to split an annual research budget of about $1.84 million over the next three years to develop a faster-than-sound plane.

A breakthrough in supersonic flight could help Japan leap ahead in the aerospace field. The country, which does much of parts manufacturing for U.S.-based Boeing Co., has only a limited domestic airplane industry.

Among the hurdles are two difficulties that plagued the Concorde, jet-engine noise and high fuel consumption. Japan has already successfully tested an engine that can theoretically reach speeds of up to Mach 5.5, or more than five times the speed of sound.

Japanese companies slated to participate in the French joint venture include Japan Aircraft Development Corp., a non-profit consortium; government's space agency Japan Aerospace Exploration Agency, Mitsubishi Heavy Industries, Kawasaki Heavy Industries Ltd., Fuji Heavy Industries Ltd. and Ishikawajima-Harima Heavy Industries Co.

French companies will be European Aeronautic Defence and Space and Safran Group, formerly Snecma-Sagem.

The Concorde first flew in 1969 and became a symbol of French and European industrial acumen. But the planes were retired from commercial service in October 2003, never having recouped the billions of tax dollars invested in them.

The Concorde exploded in flames after takeoff from Charles de Gaulle airport near Paris on July 25, 2000, and slammed into a hotel. The accident, which killed the 109 people on board, presaged an end to the career of the sleek but costly supersonic aircraft.

Japan hopes to have a successor making regular flights by 2020.