Nuri space rocket is lowered from the launch pad to be transferred back to the assembly building at the Naro Space Center in Goheung, South Jeolla Province, Wednesday, after Korea Aerospace Research Institute (KARI) researchers found technical problems in the oxidizer tank. Joint Press Corps

Problem detected in oxidizer tank level sensor

By Baek Byung-yeul

The launch of the Nuri space rocket was called off after researchers found technical problems in the oxidizer tank, the Ministry of Science and ICT and the Korea Aerospace Research Institute (KARI) said Wednesday.

"The Ministry of Science and ICT and KARI decided to cancel the launch of the Nuri tomorrow after a sensor abnormality was found while conducting a pre-launch inspection," the ministry said in a statement at 5:33 p.m.

"Inspections were conducted on sensors at each stage of the Nuri rocket, which left the assembly building and was transferred to the launch pad," it said. "Abnormalities were detected while checking signals of level sensors on the oxidizer tank in the first stage," the ministry added.

The level sensor measures the amount of oxidant in the oxidizer tank.

The science ministry also noted that KARI researchers are analyzing the cause and the launch date will be set again after completing the analysis.

KARI said it confirmed the problem with the level sensor at 2:05 p.m. after the Nuri was placed on the launch pad at Naro Space Center in Goheung, South Jeolla Province.

"We judged that it was impossible to proceed with the launch preparation as it was difficult to check while the space rocket was in a standing position," a KARI researcher told reporters during a briefing. "We reported it to the launch management committee, which decided to transfer the rocket to the assembly building for inspection."

The Nuri was originally scheduled to be positioned on the launch pad on Tuesday for liftoff the following day. But authorities decided to delay the schedule by one day after strong winds at the launch site raised safety concerns.

The Nuri departed from the assembly center at Naro Space Center in Goheung, some 470 kilometers south of Seoul, at 7:20 a.m. on Wednesday and arrived at the launch site at 8:30 a.m. But it was moved back to the assembly building later in the day.

The three-stage space rocket is designed to push a 1.5-ton satellite into low orbit between 600 kilometers and 800 kilometers above the Earth. Thursday's launch will be its second trial, following a failure in October 2021.

During its first launch, the Nuri flew to a target altitude of 700 kilometers, but failed to put a dummy satellite into orbit as its engine burned out 46 seconds earlier than expected.

KARI conducted a two-month-long investigation and concluded that the failure stemmed from the loosening of a device that anchors a helium tank, which was mounted inside the oxidizer tank in the third stage of the rocket.

To prevent a repeat of the same mistakes, Jang Young-soon, director of KARI's Launcher System Development division, told reporters on June 10 that the institute "improved the helium tank by strengthening the anchor on the lower support and reinforcing the thickness of the manhole cover."