The long-anticipated maiden flight of Japan's new flagship H3 rocket was aborted Friday after a system onboard the craft detected an abnormality and did not ignite its booster engines, the Japan Aerospace Exploration Agency said.

The abrupt halt, moments before launch, marked a setback for the program, already hit by a string of delays, as the country seeks to gain a foothold in the increasingly competitive satellite-launching business with the successor to its highly reliable H2A launch vehicle.

The H3 rocket, carrying a land observation satellite as its payload, did not lift off from the Tanegashima Space Center on Tanegashima Island in the southwestern prefecture of Kagoshima on Friday morning, even as the launch countdown ended.

"An onboard system detected an abnormality and did not send ignition signals to the boosters," said JAXA project manager Masashi Okada in an online press conference in the afternoon, adding that there was no problem with the main engine.

Japan's new flagship H3 rocket fails to lift off at the Tanegashima Space Center in Kagoshima Prefecture, southwestern Japan, on Feb. 17, 2023. (Kyodo)

"It is difficult to call it a failure," Okada repeatedly said, stressing that the safety features had worked properly. "The system had recognized the anomaly, and the launch was soundly aborted" as designed, he added.

The boosters are attached to the sides of the core airframe.

Okada sounded emotional at times, apologizing to the people who had worked on the project and the public who had come to watch the liftoff.

The agency is planning to try again in a week or two, a government official said. But Okada suggested that the agency is seeing a slightly longer time frame, saying it will attempt to launch by the end of March after doing checks.

The agency has set aside the period between Feb. 18 and March 10 as a secondary launch window.

"After clarifying the cause of the problem, we hope that the H3 will continue or even exceed the reliability of 2A, which is itself highly reliable," he added.

It was a great disappointment for the 1,000 or so people who had come to watch the occasion from a park around 6 kilometers away from the space center.

The crowd roared when white smoke came out from the launch pad area, and children shouted to urge the rocket to fly.

A family of four who had dreamed for over 10 years about watching a rocket launch came all the way from the western prefecture of Yamaguchi.

"It was so sad seeing the smoke go away, and I almost cried," Harumi Yoshidomi, a 35-year-old homemaker, said.

The rocket is supposed to give Japan continued access to space by launching satellites and probes related to government missions. It is also seen as key to the country's participation in the next generation of space development, including the U.S.-led lunar exploration program.

Aboard the rocket is the Advanced Land Observing Satellite-3, which is expected to become a key tool for the government's disaster management efforts.

The satellite also carries a sensor from the Defense Ministry's acquisition agency capable of detecting two types of infrared rays. It will be tested to see if it can detect ballistic missile launches.

"I do not think this will have an immediate effect on our country's space policy," Chief Cabinet Secretary Hirokazu Matsuno said later Friday.

The H3 rocket is the first revamp of the country's main launch vehicle in around 20 years.

It was originally scheduled to be launched by the end of March 2021, but the date was pushed back by around two years due to issues with the newly developed LE-9 first-stage engine and for parts replacement following an Epsilon-6 rocket launch failure in October.

The failure of that smaller rocket meant that last year marked the first time in 18 years that there was not a single successful launch of a domestically developed rocket in Japan.

The H3 rocket is expected to carry a new unmanned cargo transporter that will deliver supplies and materials to the International Space Station and Gateway, a lunar-orbiting outpost planned under the U.S.-led Artemis space program.

At 5 billion yen ($37 million), the H3 rocket costs around half as much as its predecessor H2A rocket, but has 1.3 times the satellite launch capacity.

Global competition has intensified since U.S. firm SpaceX, which boasts a strong track record in rocket launches, entered the market.

Japan hopes to increase orders for satellite launches from domestic and international clients by promoting the 97.8 percent success rate of the H2A rocket, which only failed once out of 46 launches since its introduction in 2001.

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