# H3 Rocket The H3 is [[Japan]]'s main launch vehicle, developed by the Japan Aerospace Exploration Agency (JAXA) and built by Mitsubishi Heavy Industries. It flies from Tanegashima Space Center, an island launch site in southern Japan. It replaced the H-IIA, which retired in June 2025 after its 50th flight. The H3's design goal was blunt: cut the cost of a Japanese launch roughly in half so the country could keep an independent rocket without pricing itself out of the market [[SpaceX]] now dominates. ## A rough start, a stumble, and a comeback | When | What happened | |---|---| | March 2023 | First flight fails. The second stage does not ignite, and the rocket is destroyed along with the ALOS-3 Earth-observation satellite. | | Feb 2024 – Oct 2025 | Five straight successes, including a Japanese military communications satellite (November 2024) and the first HTV-X cargo ship for the [[International Space Station]] (October 2025). | | December 2025 | Eighth H3 fails and the Michibiki 5 navigation satellite is lost. JAXA traced the cause to a damaged payload adapter — the fitting that holds the satellite to the rocket — which also damaged the second stage's fuel tanks. | | June 2026 | Return to flight, and the first flight of the H3-30 version: three main engines, no side boosters, Japan's cheapest configuration. All six small satellites reached orbit. | | 11 August 2026 | Successful launch of Michibiki 7. Seven of nine H3s launched to that point had succeeded. | ## What it carries - **Michibiki.** Japan's Quasi-Zenith Satellite System is a regional navigation constellation that sharpens and backs up [[GPS]] over Japan and the Asia-Pacific. Its purpose is partly practical (accuracy in cities and mountains, where GPS struggles) and partly strategic: a country this exposed to [[China]] and [[Russia]] does not want its positioning to depend entirely on a U.S. military system. That is why losing Michibiki 5 in December 2025 hurt. - **Defense satellites.** Japan's military communications and intelligence satellites ride on H3. As Japan moves toward its largest defense buildup since World War II, the rocket is part of that plan. - **Moon missions.** Japan is a core [[Artemis Program]] partner. A 2024 agreement with [[NASA]] has Japan providing a pressurized lunar rover in exchange for seats on future Moon landings, so a Japanese astronaut is in line to walk on the Moon. ## Why it's on the map The H3 is how a close U.S. ally hedges against the two dependencies this wiki tracks in space: dependence on rivals and dependence on a single American company. Japan could buy every launch it needs from [[SpaceX]]. It pays to keep its own rocket because launch is security infrastructure, especially for a country that sits within missile range of China and North Korea and whose leadership under [[Sanae Takaichi]] has pushed for a harder security posture. The H3's failures also show how expensive and unforgiving that independence is: each failed launch erases years of work on the satellite it was carrying. ## See also - [[Japan]] — the country - [[Artemis Program]] · [[NASA]] — the lunar partnership - [[GPS]] — the U.S. system Michibiki augments - [[Space Launch Infrastructure]] — launch as a strategic chokepoint - [[Ariane]] · [[GSLV]] · [[Long March Rockets]] — the other national launchers - [[Space Hub]] — the parent hub