On September 29, the Japan Aerospace Research and Development Agency of the Ministry of Science of the Ministry of Science of Japan at the conference of the Space Development and Utilization Special Panel that the H3 carrier rocket No. 6 failed in the engine combustion test in July this year, and the launch originally planned for this fiscal year may not be carried out as planned.

The H3 carrier rocket is a new-generation main-power carrier rocket in Japan, developed jointly by the Japan Aerospace Research and Development Agency and Mitsubishi Heavy Industries. The five H3 rocket previously launched are all in the "22S" configuration, i.e. the first-level archery main engine uses two liquid fuel LE-9 expansion circular hydrogen engines, and is also equipped with two solid fuel propellers. while the H3 carrier rocket 6 uses a "3-0" new configuration, i.e. uses three liquid fuel main engines without a propeller. This will be the first large liquid fuel carrier rocket launched by Japan without a push.

According to reports from Japan's Kyodo News, Sankei Shimbun and other media, Japan Aerospace Exploration Agency reported on the 29th that although the ignition test of the first-stage rocket bench of the "3-0" configuration of No.6 aircraft conducted in July fully obtained the operating data of the rocket body and equipment, the pressure of hydrogen and oxygen fuel tanks failed to meet the standard during the test, making it difficult to provide enough fuel to the main engine. It will take time to resolve this issue and re-conduct bench ignition tests, which may prevent Unit 6 launches from happening as originally planned in fiscal year 2025 (April 2025 to March 2026).

Japan's space aviation research and development agency said that the above is a "3-0" composition-specific problem, which does not affect the H3 rocket number 7, which uses solid propellers, and the 7 will still be launched as planned in late October this year.

At the meeting of the same day, the Japan Aerospace Research and Development Agency also the relevance of the small solid-fuel rocket "Epsilon S" under development. The rocket occurred during the second-tier engine combustion test conducted in November 2024 and caused fires. The agency said it was considering changing the development plan to change the second-tier engine of the "Epsilon S" from the E-21 being developed to the M-35 engine used by its predecessor, the "Epsilon Reinforced".

The Japanese Aerospace Research and Development Agency is considering changing the engine in order to put the Epsilon S into practical use as soon as possible, but this change will cause its launch capacity to be lower than the original target.