H-IIB was a more powerful version of H-IIA to support the now-retired Kounotori H-II Transfer Vehicle (HTV). Launch of the H-IIA Flight 40 with IBUKI-2 (GOSAT-2) and KhalifaSat – via JAXA H-IIA took its maiden flight in 2001 and currently sits at 43 launches with 42 successes. H-IIA is the same 4-meter diameter as H-II but taller at 53 meters.
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It uses a single LE-7A first-stage hydrolox engine, a single LE-5B second-stage hydrolox engine, and two or four SRB-A solid rocket boosters. H-IIA is Japan’s main launch system currently in operation. The H-II was then retired in favor of the H-IIA and H-IIB rockets. It flew seven times from 1994 to 1999 with five successful launches. The rocket was 4 meters in diameter with a height of 49 meters. H-II also included a single upgraded LE-5A hydrolox second-stage engine and twin Japanese-built solid rocket boosters. The ELTT first stage was replaced by a Japanese-built first stage now powered by a single LE-7 hydrolox engine. The H-I was replaced in 1994 by the H-II, the first all Japanese-built liquid rocket. The H-I successfully flew nine times with a 100% success record. The H-I was 2.44 meters in diameter and had a height of 42 meters. This was the first Japanese rocket to use a Japanese-built cryogenic second stage using their new LE-5 engine. Then, the vehicle used an American-built Extended Long Tank Thor (ELTT) with either six or nine Caster-2 solid rocket boosters (SRBs). The first was the H-I rocket used from 1986 to 1992. The H3 rocket is the third in Japan’s hydrogen-powered rocket family. The H3 rocket is co-developed by the Japan Aerospace Exploration Agency (JAXA) and Mitsubishi Heavy Industries (MHI), succeeding the H-II family, which provided satellite launches and International Space Station cargo resupply missions for two decades. Japan’s third-generation liquid hydrogen-powered rocket, H3, is nearing closer to its first launch.