H3 Rocket Launch: Find out Cause of Failure and Work to Restore Trust

Editorial

15:48 JST, December 24, 2025

The failed launch of the large H3 rocket has cast a dark shadow over the future of Japan’s space development. It is necessary to swiftly find out the cause and aim to resume launches as early as possible.

The No. 8 H3 rocket, jointly developed by the Japan Aerospace Exploration Agency and Mitsubishi Heavy Industries, Ltd., was launched. As the second-stage engine of the rocket did not properly ignite after launch, it ended in failure.

The Cabinet Office’s Michibiki No. 5 positioning satellite, which was carried by the No. 8 H3 rocket, could not reach its intended orbit and is believed to have been lost.

An abnormal shock was recorded when the cover to protect the satellite separated from the rocket 3 minutes and 45 seconds after launch. This problem with the separation could have impacted the second-stage engine, according to JAXA.

The No. 1 H3 rocket, which was launched in 2023, also failed due to an electrical system problem in the second-stage engine. The No. 2 rocket launched in 2024 succeeded, followed by five consecutive successful launches up to the No. 7 rocket. Considering that, this latest failure is a significant setback.

In the first place, the development of the H3’s first-stage engine was delayed, causing the launch of the No. 1 rocket to be postponed. The plan to make up for the delay by achieving stable operations and enhancing Japan’s global competitiveness has been derailed by the latest failure. Trust, which has been damaged, must be restored.

The original plan was to launch the Michibiki No. 7 satellite in February next year, completing the seven-satellite constellation system needed to cover all of Japan.

Japan having its own high-precision location information system is also crucial for its national security. However, as the launch of H3 rockets will be suspended for the time being, the completion of the seven-satellite constellation system will inevitably be significantly delayed.

H3 rockets also had other important missions scheduled, including launching a probe to one of Mars’ moons and transporting supplies to the International Space Station. If this situation continues, all of Japan’s space development activities will stagnate. The cause must be figured out with care and a sense of urgency.

Regarding Japan’s rockets, in addition to H3 rockets, JAXA’s small Epsilon S rocket also caused an explosion during a ground combustion test, stalling its development. The launches of the No. 1 and No. 2 Kairos rockets from the startup Space One Co. also failed.

Although failures are inevitable in the early stages of rocket development, such a spate of setbacks raises questions about whether technology is properly being passed down in the field and whether there is complacency within the organization or systems

It is hoped that JAXA and those involved with manufacturers will overcome these failures and continue to take on future challenges with tenacity.

(From The Yomiuri Shimbun, Dec. 24, 2025)