Japan’s H3 rocket successfully entered orbit on its second launch on February 16, almost a year after its failed first launch. The H3 rocket lifted off from Tanegashima Space Center at 7:22 PM ET after a two-day delay due to weather conditions. No problems were reported during the countdown, as the breakout occurred at the beginning of a time interval lasting more than two and a half hours.

The most important moment of the launch was the separation of the acceleration stage and the ignition of the LE-5B-3 engine. During the vehicle’s initial launch in March 2023, this engine failed to ignite, causing controllers to issue the command to destroy the stage and its payload, the ALOS-3 Earth observation satellite.

The engine caught fire during this launch, which the Japanese space agency JAXA called H3 Test Flight 2 (H3TF2). Stage reached a preliminary orbit of approximately 674 kilometers 16 and a half minutes after liftoff and, a few minutes later, deployed one of its payloads, the CE-SAT-1E satellite built by Canon Electronics. It would be followed about nine minutes later by another secondary payload, a cubesat called TIRSAT.

The second upper stage burn was planned to last 1 hour 47 minutes after launch and lasted 26 seconds. The upper stage will then deploy its primary payload, a mass simulator called Vehicle Evaluation Payload (VEP) 4. VEP-4 is a metal column with the same mass and center of gravity as ALOS-3. JAXA flew a idle payload on the rocket’s first launch following criticism over the flight of ALOS-3, a $200 million satellite.

JAXA and the vehicle’s prime contractor, Mitsubishi Heavy Industries, spent months investigating the initial launch failure. Engineers concluded that although the rocket received a signal to ignite the engine, an electrical malfunction prevented the ignition system from working.

Although no root cause was found during the investigation, three scenarios were found that most likely explained what happened: a short circuit in the wiring in the ignition system, a failure of a transistor in the ignition system, and a failure of a computer in the stage. A control system that sends an electrical current to a standby computer, causing it to malfunction. JAXA has made changes to prevent any of these scenarios from happening again.

Possible problems with the ignition system also affected the older H-2A rocket, which used a version of the same booster engine. This grounded the H-2A for half a year, and the missile returned to flight in September.

H3 is key to Japan’s future space plans. The rocket will replace the H-2A and launch civilian and military missions, including the new HTV-X spacecraft, which will carry cargo to the International Space Station. The H3 was also designed to operate at a much lower cost than the H-2A, making the vehicle more competitive in the commercial launch market.