New details have emerged regarding Japan’s H3 rocket failure last month, revealing the strange way its payload—a navigation satellite—was lost prior to reaching its target orbit.
Japan Aerospace Exploration Agency (JAXA) launched the seventh mission of its H3 rocket on December 21, 2025, carrying the Michibiki 5 satellite. Shortly after liftoff, the rocket’s second-stage engine suffered an anomaly that caused it to shut down prematurely. JAXA officials recently revealed the root cause of the rocket anomaly: The protective cone-shaped covering that encased the satellite, known as a payload fairing, came apart around 4 minutes after launch. As a result, the satellite was left fighting for its life before it inevitably fell back to Earth.
An illustration of the payload fairing anomaly. Credit: JAXA
JAXA shared extensive information about the recent anomaly, including this helpful illustration of the payload fairing breaking off from the rocket.
Anomalous anomaly
The rocket business is undoubtedly tricky, and launches fail in all sorts of ways. This incident, however, may be one of the strangest ways a rocket has failed to deliver its payload.
The 207-foot-tall (63-meter) rocket had a rocky debut, ending in a self-destruct command just 15 minutes after its first launch on March 6, 2023. Since its failed first launch, however, H3 has pulled off five successful missions to date.
Shortly after the recent failed mission, JAXA stated that telemetry data showed that pressure in the second stage’s hydrogen tank began dropping during the first stage engine burn. As a result, the first stage engine cutoff took place 27 seconds later than planned, delaying the second ignition by 15 seconds. At the time, it wasn’t yet clear if the satellite had separated from the rocket.
JAXA officials began an investigation into the anomaly and discovered that the pressure began to drop when the rocket accidentally jettisoned its payload fairing. The satellite and payload adapter may have been damaged by the shock of the fairing separation.
Footage captured by a camera mounted on the adapter showed the satellite with apparent damage to its panels and insulation after the payload fairing had come off. A shower of debris surrounded the satellite, which clung to the rocket without its protective casing.
The navigation satellite on its way back to Earth. Credit: JAXA
After the first stage shut down and separated, the jolt dislodged the satellite from its mooring, causing it to fall away from the rocket. The camera showed the satellite lost in Earth orbit during its untimely descent back to Earth. JAXA officials stated that the satellite fell in the Pacific Ocean, in the same area as H3’s first stage.
Lost in space
JAXA still does not know why the payload fairing suddenly came apart, and that part of the anomaly remains under investigation.
Japan’s H3 rocket was 11 years in the making, a successor to the H-2A, which the agency retired in June 2025. Prior to its latest failure, JAXA had been aiming for at least two H3 launches per year. The rocket was due to launch another QSZ satellite in 2026, as well as Japan’s HTV-X cargo spacecraft. Japan’s Martian Moons eXploration (MMX) mission is also scheduled to launch on board the H3 rocket in late 2026.
The unusual payload fairing separation, however, may force the space agency to delay its plans.