Japan's space agency says it aims to launch the next-generation mainstay H3 rocket in the current fiscal year ending in March.

The H3 rocket is under development as the successor to the H2A rocket. The H3's first launch was initially planned for fiscal 2020, but it was postponed twice due to problems with the main engine.

The Japan Aerospace Exploration Agency, or JAXA, announced the new plan at a news conference on Thursday. It cited progress in the development of the main engine.

Engineers said they found vibrations that were different from what they had expected in a component called the turbopump that sends fuel to the main engine. They also said they resolved the problem after reviewing the design and repeating combustion tests.

JAXA plans to conduct tests with engines to be installed in the first H3 rocket, starting this month.

Project Manager Okada Masashi said he feels the staff has finally reached the starting line. He also said a tough road will continue, and he thinks the real challenge has started.

The H3 rocket is 63 meters long and designed to have a payload about 30 percent heavier than that of the H2A.

The new rocket will also be used in the US-led Artemis program, which aims to put humans on the Moon.

JAXA is working to cut the launch cost of the rocket to about half of the H2A to compete with foreign rivals in the space business.