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As launch date approaches, fourth Nuri rocket undergoes last big test

Published: 17 Sep. 2025, 18:57 Updated: 17 Sep. 2025, 19:53

The Nuri rocket stands on the launch pad at the Naro Space Center in Goheung County, South Jeolla, for final testing ahead of its fourth launch on Sept. 16. [KOREA AEROSPACE RESEARCH INSTITUTE]

GOHEUNG, South Jeolla — At the Naro Space Center in Goheung County on Tuesday afternoon, reporters climbed the road that winds from the assembly building to the launch pad. After five minutes, the fourth Nuri rocket — known as Flight Model (FM) 4 — appeared, its 47.5-meter (155.8-foot) frame rising above the pad.

The rocket had been rolled out of the assembly building earlier on Tuesday morning and connected to the umbilical tower, which supplies fuel and power. As this reporter drew closer, a steady hiss grew louder, the sound of air being pumped in to maintain the rocket’s internal pressure.

Preparations for the Wet Dress Rehearsal (WDR), a crucial pre-launch test held two months before liftoff, were in full swing.

What's a WDR?

The Nuri rocket is loaded onto the launch pad at the Naro Space Center in Goheung County, South Jeolla, for final testing ahead of its fourth launch on Sept. 16. [KOREA AEROSPACE RESEARCH INSTITUTE]

The WDR is a critical pre-launch test in which engineers load the rocket with liquid propellants but stop short of igniting the engine. The test runs with only the rocket, without the satellite or any of its pyrotechnics.

“Extreme cold propellant at minus 183 degrees Celsius [minus 297.4 degrees Fahrenheit] causes metal components to contract in ways you can’t see at room temperature, so we conduct WDR to verify the system behaves as expected,” said Park Jong-chan, head of the Korean Launch Vehicle Enhancement Program at Korea Aerospace Research Institute (KARI).

The rocket rollout and tower connection were completed as planned, but a helium line leak delayed the oxidizer loading test until Thursday.

“The purpose of the WDR is to check for precisely these kinds of issues in advance," the Korea Aerospace Administration (KASA) said. "We confirmed that there is no problem with the launch vehicle itself.”

Why WDR matters

The Nuri rocket is erected on the launch pad at the Naro Space Center in Goheung County, South Jeolla, for final testing ahead of its fourth launch on Sept. 16. [KOREA AEROSPACE RESEARCH INSTITUTE]

This is only the second time a WDR has been conducted for Nuri since its first launch in 2021. It was skipped during the second and third launches in 2022 and 2023.

Park said there are two reasons for conducting it this time: Hanwha Aerospace, not KARI, led the entire manufacturing process for the first time, and a 30-month gap has occurred since the last launch, which was in May 2023.

“FM 4 is the first rocket built under a system integration model led by a private company. Given the new production setup and the long gap since the previous launch, we decided to be extra cautious and run the WDR," Park said.

"We do not plan to do this for the fifth and sixth launches,” he added.

Shift to the private sector

The Nuri rocket is moved to the launch pad at the Naro Space Center in Goheung County, South Jeolla, for final testing ahead of its fourth launch on Sept. 16. [KOREA AEROSPACE RESEARCH INSTITUTE]

The fourth Nuri launch marks a significant milestone as Korea transitions its space program from government-led development to increased private sector involvement. The first three Nuri rockets were developed under KARI’s lead.

While KARI still oversees the launch itself, Hanwha Aerospace now manages subcontractors and leads the entire assembly process.

Private sector participation will expand further in the fifth and sixth launches, scheduled for next year and 2027.

This launch is also the first since the establishment of KASA. Its chief, Yoon Young-bin, said, “This is the starting point of the transition from government-led to private-led space development. We aim to create an ecosystem where private companies can freely operate using their own launch capabilities.”

Next steps

The launch is expected in late November. After reviewing WDR results, the launch management committee will set the final date during its Sept. 26 meeting.

The rocket will carry Korea Aerospace Industries’ Next-Generation Medium-Sized Satellite No. 3 as its primary payload, along with 12 CubeSats developed by domestic companies, universities, and research institutes.

The goal is to place a total of 1,050 kilograms (2,314 pounds) of satellites into a sun-synchronous orbit at 600 kilometers (373 miles), passing over the same region at the same time every day.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY EO HWAN-HEE [[email protected]]