Video footage taken on Dec. 22 at the Tanegashima Space Center in Kagoshima Prefecture shows the launch of an H3 rocket that ultimately failed to place its satellite into the planned orbit. (Kazushige Kobayashi)

Photo/Illutration The eighth H3 rocket lifts off from the Tanegashima Space Center in Kagoshima Prefecture on Dec. 22. (Kazushige Kobayashi)

Japan’s space agency failed in its latest attempt to launch its flagship rocket, leaving it unable to place a key component of the country’s satellite positioning system into orbit.

The eighth unit of the H3 rocket blasted off from the Tanegashima Space Center in Kagoshima Prefecture on Dec. 22, according to the Japan Aerospace Exploration Agency.

It carried the Michibiki No. 5 satellite, which is designed to improve the accuracy of location information for smartphones and car navigation systems.

JAXA said the second‑stage engine stopped burning prematurely. Pressure in the fuel tank dropped, resulting in lower‑than‑expected thrust.

The agency has not yet confirmed whether the satellite successfully separated from the rocket.

JAXA apologized for failing to meet public expectations, while the science ministry pledged a full investigation into the cause of the failure.

The launch had already faced multiple delays. It was initially scheduled for Dec. 7 but was postponed due to equipment issues.

A second attempt 10 days later was automatically aborted moments before liftoff when a water‑cooling system for the engine failed to supply sufficient water.

The H3 was developed by JAXA and Mitsubishi Heavy Industries Ltd. as a lower‑cost successor to the H2A, which flew its final mission in June.

While the H3’s first flight ended in failure, subsequent launches had been successful. Had the latest launch proceeded as planned, JAXA intended to send up the H3 No. 9 with Michibiki No. 7 as early as February.

Yasunori Matogawa, a space engineering specialist and professor emeritus at JAXA, said the rocket appeared to lack the necessary velocity required to reach orbit.

“This time, the velocity seemed slightly insufficient, and the altitude began to drop midway,” he said, noting that some missions can still succeed despite an early engine shutdown.

Michibiki spacecraft operate within the Quasi‑Zenith Satellite System, a multi‑orbit network, which is designed to ensure that at least one satellite remains near the zenith over Japan at all times.

By transmitting signals from almost directly overhead, the system reduces interference caused by buildings and mountains.

The failed launch was expected to increase the number of quasi‑zenith satellites in the system from three to four, improving signal stability and accuracy.

Including two satellites already in geostationary orbit, the system currently operates with five spacecraft.

In a successful scenario, Japan would have placed seven satellites in the system by February, enabling the country to maintain domestic positioning services even if the U.S. GPS became unavailable.

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