H3 Launch Failure Leaves Japan Without Core Rockets, Deals Blow to Global Competitiveness in Space Development

By Chika Ishikawa and Hiroyuki Oyama / Yomiuri Shimbun Staff Writers

17:45 JST, December 23, 2025

Japan will not be able to launch satellites and probes for the time being, after the failed launch on Monday of the eighth H3 rocket, the nation’s large main rocket. This has put Japan in a critical situation in which it cannot move forward with its own space development.

Amid a global surge in rocket launches, Japan’s international competitiveness in this sector will unavoidably decline.

Hiroshi Yamakawa, president of the Japan Aerospace Exploration Agency, apologized at a press conference on Monday. “We want to make every possible effort to determine the cause and use our findings to resume launches soon,” Yamakawa said.

Launched at 10:51 a.m. on Monday, the No. 8 H3 rocket separated its first-stage rocket and other sections as planned. The second-stage engine was scheduled to stop once after starting combustion and then reignite, but combustion ceased immediately after reignition about 25 minutes after the launch.

About 3 minutes and 20 seconds after the launch, another anomaly occurred in which pressure dropped in the second-stage engine’s hydrogen fuel tank, and the propulsion power failed to increase sufficiently.

JAXA is hurrying to confirm whether the Cabinet Office’s Michibiki No. 5, a positioning satellite that was carried aboard the No. 8 H3 rocket, separated from the rocket.

“Some kind of abnormality may have occurred in the second stage rocket engine or its control system,” said JAXA’s H3 Project Manager Makoto Arita.

The No. 8 H3 rocket was originally scheduled to be launched on Dec. 7, but this was postponed due to a malfunction in equipment that measures the rocket’s attitude and velocity. A Dec. 17 launch was canceled at the last minute due to a ground facility problem.

The H3 is the successor to the H2A, which was retired in June. To halve the launch cost from the H2A’s ¥10 billion and enhance international competitiveness, a new first-stage engine was developed, bringing the total development cost to about ¥240 billion.

During the launch of the No. 1 H3 rocket, the second-stage engine failed to ignite, leading to the satellite being destroyed on command. Investigating the cause took about seven months.

“It’s not yet clear if the cause of this latest failure lies in the second-stage engine, but the second-stage engine involves complex control processes under microgravity, making it prone to problems,” said Prof. Ko Ogasawara of Tokyo University of Science, an expert in aerospace engineering.

Growing gap with overseas competitors

Rockets that are given launch priority for government satellites and probes are called “core rockets.” They are essential to promote Japan’s independent space development.

Japan currently has two such rockets: the H3 and the new solid-fuel rocket “Epsilon S” under development.

JAXA intends to suspend H3 launches until the cause of the failure is identified. The Epsilon S caused an explosion during a combustion test in November last year, delaying its development. This latest launch failure on Monday has left Japan without any core rockets for the present.

According to a draft revision of the road map for the Basic Plan on Space Policy, finalized by the government’s Committee on the National Space Policy on Dec. 9, about 30 satellite and probe launches using the H3 are planned over the next 10 years.

Expectations are high for international cooperation, including the launches of probes bound for Mars’ moons, as well as those of meteorological satellites and intelligence-gathering satellites.

In the future, launches will be transferred to private operations by Mitsubishi Heavy Industries, Ltd., with the company also aiming to expand its commercial launch orders.

An official in charge from the Cabinet Office’s National Space Policy Secretariat expressed confusion — “until the cause is determined, we can’t be certain about the impact on the plan,” the official said.

Amid a global surge in rocket launches, the H3 launch failure could potentially stall Japan’s space development.

According to the Cabinet Office, there were 253 successful rocket launches worldwide in 2024, nearly tripling from 85 in 2015. The United States led with 153 launches, nearly 90% of which were by U.S. space company SpaceX. China followed with 66 launches, while Japan had only five.

Globally, the main role in space development is shifting from governments to the private sector. Although space-related startups are growing domestically in Japan, they must rely on other countries for launches, raising concerns that the gap with overseas competitors could widen.