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Glitch behind Japan's suspended rocket launch
Publication Date : 29-08-2013
Tuesday’s last-minute cancellation of the first launch of Japan's new Epsilon solid-fuel rocket was due to a computer glitch at the ground control centre, in which an error was mistakenly identified in the rocket’s positioning.
On Tuesday evening, Japan Aerospace Exploration Agency (Jaxa)president Naoki Okumura apologised for the glitch at the Uchinoura Space Centre in Kimotsuki, Kagoshima Prefecture, where the rocket was scheduled to blast off at 1:45pm.
“I regret that Jaxa failed to launch the rocket as scheduled, bringing disappointment to the nation and organisations involved,” Okumura said.
According to Jaxa, it made a final decision to launch the rocket at 1:15pm Tuesday, as it found no problems in terms of preparation and weather conditions. The automated launch system was activated 70 seconds before the planned launch, and necessary processes were started. However, the system automatically shut down 19 seconds before launch.
According to Jaxa project manager Yasuhiro Morita, the fourth-stage engine in the upper part of the Epsilon that is used to put a satellite in orbit, is equipped with a sensor that detects positioning errors.
The rocket’s computer system starts calculating the rocket’s position based on data collected by the sensor 20 seconds before a launch.
The results are then sent to a computer system at the ground control centre, which judges whether the rocket is positioned correctly.
On Tuesday, the calculation started 20 seconds before the launch, as scheduled, but the ground control computer determined the rocket was incorrectly positioned one second later based on data sent from the rocket’s computer. An incorrectly positioned rocket cannot maintain a planned flight path.
However, Jaxa said its remote monitoring system did not detect a positioning error.
Morita said there could have been trouble in the data transmission between the rocket and ground control. The space agency plans to examine the relevant computer hardware and software in detail.
Jaxa found no abnormalities when it conducted a simulated launch a week ago. The simulation is usually halted 18 seconds before a launch because the battery for the first-stage engine is activated 15 seconds before a launch, thus requiring battery replacement and other work.
Jaxa will examine whether there were any problems during the simulation.
Aborted rocket launches are not unusual. In 2000, the countdown for the launch of M5 rocket-4, the predecessor of the Epsilon, was suspended one minute before launch due to connection trouble in the computer system that tracks the rocket’s flight course.
Regarding Tuesday’s cancellation, Daido University president Akira Sawaoka, an expert on space development, said data may have interfered with each other, resulting in the detection of an error, since various types of data are transmitted prior to a launch.