“he dropped it” during the launch

If someone asked you to imagine how a rocket launch could fail, you would normally think of an explosion, an engine failure, or a maneuver that goes wrong. What almost no one would have chosen as an answer is this: a rocket that takes off and, in the middle of the trip, “runs out of a satellite.” That’s what happened to the Japanese H3 in its last attempt to launch a navigation satellite into orbit, a mission that ended in the most absurd way possible, with the payload breaking loose prematurely and falling back to Earth.

The launch. To understand why this case has attracted so much attention, it is worth setting the scene. On December 22, 2025, H3, the Japanese space agency’s most modern launcher, took off from Tanegashima with the Michibiki 5 satellite on board, a navigation device weighing about five tons. As explained by JAXA on December 25the mission ended in failure because the second firing of the second stage engine did not start normally and stopped prematurely, which prevented reaching the planned orbit. From there, the agency activated a specific team to investigate the origin of the failure and reconstruct minute by minute what happened during the climb.

This is how JAXA draws it so that no one has to imagine it: separation of the cap and a satellite that begins to go freely

What is the cap and why is it separated?. The cowl is the cover that protects the satellite during the first minutes of launch, when the rocket is still passing through the densest layers of the atmosphere and the payload is exposed to vibrations, friction and possible impacts with particles. It is a piece made up of two halves that open and detach when the vehicle is high enough so that this protection is no longer necessary. The normal thing is that it is a routine step, quick and without consequences. In this case, however, it is the moment that appears in the center of all eyes.

Diagram of the H3 cowl opening and separation system

The problem. According to the reconstruction presented by JAXAthe critical moment comes just after the separation of the fairing, around 3 minutes and 45 seconds after takeoff. In the images from the onboard cameras, a kind of “rain” of fragments can be seen around the satellite and, in the following seconds, an anomalous behavior: it begins to oscillate and tilt. At the same time, the rocket’s sensors detected accelerations outside of expectations in the junction area between the satellite and the launcher, an indication that something was not going well at that interface.

“Ghost flight”. The strangest thing is that, despite that initial blow, the satellite did not detach immediately. The connecting structure was damaged at that moment, but the assembly continued flying as if nothing had happened during the remaining combustion of the first stage. The explanation is almost domestic: as the rocket continued to accelerate, that acceleration acted as a kind of constant pressure that kept the satellite supported on its base, even if the fixation was no longer reliable. The outcome came with the shutdown of the main engine, the moment known as MECO. With that force gone, Michibiki 5 separated early, just before the second stage could take control and place it into orbit.

More consequences. During that same flight segment, a pressure drop was also confirmed in the liquid hydrogen tank of the second stage. The working hypothesis is that the same event that damaged the satellite docking could have affected the pressurization line, and that is why the pressure did not recover even though the system tried to compensate for it. With this scenario, the second stage engine did start, but it did so at a penalty. The result was a kind of “partial salvage,” enough to reach a low orbit, but not to complete the planned profile, and the stage ended up re-entering and disintegrating in a matter of hours.

What do we know. The JAXA indicates that the satellite would have detached and fallen into the Pacific Ocean in an impact zone planned for debris from the launch itself, east of Minamitorishima, and no damage has been reported on the ground. The agency has presented a failure analysis in which it keeps several possibilities open to explain the anomalous blow recorded at the time of releasing the cap: from an impact or collision with a fragment to the sudden release of tensions in the union system. It is also carefully considered whether any element of the system could have generated an abnormal acceleration at that time.

A key rocket. The H3 is a modern rocket, but still young, and every anomaly counts double when trying to build a reputation. This launch was his eighth and his record combines six successes with two failures. The impact on the agenda has not been long in coming. Science Portal points out that JAXA and Mitsubishi Heavy Industries have postponed the next launch, scheduled for February 1 with another Michibiki satellite, after announcing the delay on January 7. Now the agency needs a response that will allow the rocket to be put back on the ramp with guarantees.

Images | JAXA

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