Japan's space agency halts Epsilon S rocket engine test after explosion

By Kantaro Komiya

Japan's space agency aborted an engine test for the Epsilon S rocket on Tuesday after it exploded and caught fire, a repeated failure that will likely push the rocket's debut launch beyond the March-end target and delay the national space programme.

The Japan Aerospace Exploration Agency (JAXA) said the combustion test resulted in an explosion of the second-stage motor 49 seconds after the ignition, causing fire at the Tanegashima Space Center in southwestern Japan.

While no one was injured and the fire was put out within an hour, the blast damaged the facility, and the cause remains unclear, JAXA's Epsilon project manager Takayuki Imoto told a media briefing.

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"We are sorry that we couldn't meet everyone's expectations...but a silver lining was that we found (the issue) at a ground test, before putting it for a flight," Imoto said, adding it will likely take at least several months to investigate the cause and take necessary countermeasures.

JAXA partnered with the aerospace unit of heavy machinery maker IHI to develop Epsilon S, the next generation in the Epsilon solid-fuel small rocket series.

Shares in IHI were down as much as 7% in Tokyo trade. An IHI Aerospace spokesperson said the company was investigating the cause.

Epsilon S's debut flight was slated by the end of the fiscal year through March 31 depending on the success of Tuesday's engine test.

The test was conducted after previous failures triggered months of investigation which have delayed space missions and satellite launch plans.

In July last year, an Epsilon S engine test failed due to thermal damage to its ignition systems. That followed a launch failure of a previous-generation Epsilon rocket in 2022.

JAXA's larger flagship rocket H3, built by Mitsubishi Heavy Industries, failed at its first launch last year but has succeeded in three flights this year, launching Japanese satellites and winning orders including from French satellite operator Eutelsat.

The H3 and Epsilon S are central to JAXA's ambition to build cost-competitive rockets amid the rise of American commercial launch providers such as market leader SpaceX and small rocket maker Rocket Lab.

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Japan's Chief Cabinet Secretary Yoshimasa Hayashi, the top government spokesperson, said at a regular press briefing that rocket development is "extremely important" to ensure the autonomy of Japan's space programme.

In the private sector, IHI-backed Space One is set to attempt the second launch of its Kairos small rocket on Dec. 14 after the first flight exploded in March. It aims to become the first Japanese business to put a satellite in orbit.