Japan's flagship launcher for the 2020s and beyond — designed to halve launch costs while increasing reliability and flexibility. The backbone of Japan's commercial and institutional launch capability.
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The H3 is Japan's new medium-to-heavy-lift launch vehicle, developed by JAXA and Mitsubishi Heavy Industries (MHI) to replace the venerable H-IIA that has flown since 2001. Its primary design goals are cost reduction (approximately half the cost of H-IIA), improved reliability through simplified design, and flexibility to serve both institutional and commercial customers.
The vehicle features the LE-9 engine, an innovative expander bleed cycle engine that uses liquid hydrogen and liquid oxygen. It comes in multiple configurations: 2 or 3 LE-9 engines on the first stage, with 0, 2, or 4 SRB-3 solid boosters, and either a short or long payload fairing. This modular approach allows H3 to address a wide range of missions from small payloads to heavy GEO satellites.
The first H3 launch attempt in March 2023 failed when the second stage engine did not ignite, resulting in a command destruct. The vehicle returned to flight successfully in February 2024 and has since conducted additional missions. H3 is essential to Japan's commercial launch competitiveness and supports JAXA institutional missions including Earth observation and exploration payloads.