Electrostatic Noise Rebooted Communication Software, and the Rocket Stopped Itself: Cause of Kairos No. 3 Failure Identified

Explanation

The small rocket "Kairos" No. 3, launched from Wakayama Prefecture on March 5, 2026, terminated its flight 68.8 seconds after liftoff (at an altitude of about 29 km). About half a year after the launch, Space One published the results of its investigation into the cause on August 30.

The cause was static electricity. Static electricity accumulated on the vehicle during flight and entered the communication lines as electrical noise. This noise reset the communication software connecting the flight safety control device and the first-stage termination device, temporarily cutting off communication between the two. The rocket's onboard autonomous flight safety system is designed to stop the flight on its own when it judges that it "might lose the means to terminate flight." In this case, it operated exactly as designed. In other words, this was not an explosion accident but the result of the system correctly "stopping" the flight. The company says it was able to reproduce this phenomenon in tests.

The countermeasures have three layers: releasing static electricity from the vehicle, improving the noise resistance of equipment, and reviewing the reset function itself. These will be applied to all electrical systems before the launch of No. 4, along with verification testing.

Kairos has now had its flight terminated three times in a row, following No. 1 (March 2024) and No. 2 (December 2024). The cause was different in all three cases.