Japan’s H3 Rocket Drops Satellite in Rare Launch Failure

Japan's space agency lost a major navigation satellite on December 22, 2025, when it fell off an H3 rocket during launch from the Tanegashima Space Center. The 5-ton Michibiki No. 5 satellite, meant to boost Japan's positioning network, separated too early after the payload cover came off, leading to damage in the rocket's fuel lines and early engine shutdown. Both the satellite and parts of the rocket likely ended up in the Pacific Ocean near a remote island.

Background

Japan has worked for years to build its own satellite system for better navigation services. The Quasi-Zenith Satellite System, or QZSS, aims for seven satellites to give precise location data across Asia and the Pacific. These would work alongside U.S. GPS signals to cut down on errors in cities where tall buildings block views of the sky. Michibiki No. 5 was the latest piece in that plan, a heavy satellite weighing about 4,000 kilograms designed for a high orbit.

The H3 rocket is Japan's main launch vehicle now that the older H-IIA retired in June 2025. Built by Mitsubishi Heavy Industries and JAXA, the 63-meter-tall rocket first flew in March 2023. That debut failed due to a second-stage issue, but six missions since then went well, including one in October 2025 that sent cargo to the International Space Station. The December flight was the eighth overall and used the H3 24L setup, meant to handle heavy payloads like this satellite.

Launches from Tanegashima happen often, but this one stood out. The site sits on a southern island, picked for its clear path over the ocean to avoid populated areas. Teams there prepared the rocket for months, loading the satellite inside its protective fairing—a nose cone that shields it during the rough ride through the atmosphere.

Key Details

The launch started at 10:51 a.m. local time. The first stage fired as planned, pushing the rocket up through the clouds. Everything looked normal at first. Telemetry data showed steady climb, good engine performance, and no early warnings.

Trouble hit about three minutes and 20 seconds in, right after the fairing split open to let the satellite breathe. Onboard cameras caught the problem: the satellite wobbled and broke free from its mount on the second stage. It tumbled away while the rocket kept going.

What Went Wrong Step by Step

Engineers reviewed footage and sensor readings. The mounting section, where the satellite bolted to the rocket, took damage during fairing separation. This let the satellite loose before the second stage fully ignited for its burn.

As the satellite fell off, it likely yanked on nearby parts. Fuel tubing for the second-stage LE-5B-3 engine, which runs on liquid hydrogen and oxygen, got hit. Pressure in the hydrogen tank dropped fast. The engine tried to fire for its second burn, which should have lasted over four minutes, but shut down early.

Automatic systems kicked in, opening valves to pump gas into the tank and fix the pressure. They failed. No leak showed up directly, but odd accelerations pointed to physical harm, maybe debris or shifting forces from the loose satellite.

The first stage separated as normal, but without the satellite attached properly, it all went off course. Data suggests the satellite and first stage splashed down near Minamitorishima, a tiny island far east in the Pacific under Tokyo's control. Recovery teams have not confirmed exact spots, as the area is remote and deep ocean.

"It is highly likely that the satellite mounting structure was damaged due to some factor, and as a result, the pressurization piping was damaged." – JAXA investigation report

JAXA held a news conference right after. Project manager Makoto Arita stressed the need to find the root cause before any more flights.

What This Means

This failure marks the second big setback for H3 since it started. Japan now lacks a working heavy rocket for key missions. The next H3, number nine, was set for February 1, 2026, carrying another satellite for the seven-satellite network. JAXA pushed that back on January 8 while teams dig into the December data. No new date exists yet.

The QZSS system stalls without Michibiki No. 5. Japan wanted all seven birds up by March 2026 for full coverage. Delays mean relying longer on U.S. GPS, which can glitch in urban canyons or bad weather. Businesses from delivery services to self-driving cars count on steady signals.

Fixing H3 costs time and money. Mitsubishi and JAXA must check designs for the mounting area and fuel lines. Ground tests might repeat launch stresses to spot weak points. Past successes show the rocket's base is solid—first stages and early guidance worked fine here—but payload handling needs work.

Other countries watch closely. SpaceX and others compete in this market, and Japan aims to sell H3 launches abroad for cash. A string of wins builds trust; losses slow that.

Teams keep sifting data. They look at vibration levels during fairing jettison, bolt strength, and how parts fit together. Camera views help map the chain: damage starts at the mount, spreads to pipes, kills the burn. Until fixed, no green light for flight nine.

Japan's space push continues. Smaller rockets like the Epsilon fill gaps, but H3 handles the big loads. Leaders say they commit full resources to solve this. The program has bounced back before, with five straight successes after the 2023 flop. This time tests that again.