On the 16th, after the sky had cleared, the Korean launch vehicle Nuri stood tall on the launch pad at the Naro Space Center in Goheung, South Jeolla. Around the pad, researchers and engineers in work clothes went up and down, absorbed in inspections. As an announcement saying, "We are currently inspecting Nuri," rang out, the checklist on the Mission Direction Center (MDC) monitors changed in real time, and a subtle tension hung in the calm air.
It had been about two and a half years since Nuri was placed on the pad after the third launch in May 2023. The site that day was in the thick of a wet dress rehearsal (WDR), the final inspection before the fourth launch. The term "wet" is used because propellant is loaded. The process sets the launch vehicle on the pad, fills it with a cryogenic oxidizer at minus 183 Celsius, and checks whether the propulsion feed line and various systems operate normally. Although propellant and satellites were not yet loaded, the inspection procedures proceeded in an urgent sequence no different from just before launch.
In particular, this WDR went beyond a simple inspection procedure and also served to test the "first privately led launch." The fourth launch, scheduled for Nov., will be the first since the launch of the Korea AeroSpace Administration and the first public-private cooperative launch in which Hanwha Aerospace participates as the system integrator.
Hanwha, which only partially took part in stage assembly for the third launch, is this time leading launch vehicle production by overseeing the entire process from partner management and stage assembly to integrated launch vehicle (ILV) assembly. In fact, many people wearing work clothes bearing Hanwha and partner company logos were visible at the Naro Space Center.
Park Jong-han, head of the Korea Launch Vehicle Advancement Program, described the WDR as "a procedure like tapping even a stone bridge before crossing." Park said, "We did not conduct a WDR for the second and third launches, but this time we needed a step to reconfirm the reliability of the first Korean launch vehicle produced under the lead of a system integrator," adding, "Since this launch comes after a two-and-a-half-year gap, it also carries the meaning of comprehensively inspecting the launch pad and overall operation systems."
The WDR runs for three days and two nights. On the first day, the 16th, the fully assembled Nuri was transported from the assembly building to the launch pad, erected, and then connected to the umbilical tower, a charging facility. Like an umbilical cord that supplies nutrients to a fetus, the umbilical tower supplies the launch vehicle with electricity, propellant, and oxidizer. Starting on the 17th, a cryogenic oxidizer is filled to check the systems under conditions equivalent to an actual launch, and on the 18th the vehicle is laid back down and returned to the assembly building.
The results of this WDR will be comprehensively analyzed and reported at the first Launch Management Committee meeting on the 26th. After reviewing the launch readiness there, the Nov. launch schedule will be finalized. Then, from early Oct. to mid-to-late Nov., integrated vehicle assembly will proceed to mount all stage separation motors, explosives, and payloads.
The goal of Nuri's fourth launch is to place the Next-Generation Medium-Sized Satellite No. 3 and 12 domestically made ultra-small CubeSats by universities and corporations into a 600-kilometer orbit above Earth. The satellite payload is 1,040 kilograms, more than double the approximately 500 kilograms of the third launch. Director General Park said, "As Nuri has the performance to lift up to a 2-ton-class satellite, the technical margin is sufficient."
The Naro Space Center has also begun preparations for the fifth launch. Inside the Launch Vehicle Integration and Assembly Building that day, stage assembly of Nuri No. 5, scheduled for launch next year, was also underway. First-stage assembly began in Jun. and will continue through Mar. next year. With the fifth launch scheduled just seven months after the fourth, researchers are preparing for both launches in parallel. Then, in 2027, the sixth launch will follow in succession.
Kim Ji-nam, senior researcher on System Integration Team 2 of the space division at Hanwha Aerospace, said, "Starting with the sixth launch, Hanwha Aerospace will use the stage assembly plant being built in Suncheon," adding, "Vehicles whose assembly is completed in Suncheon will be transported to the Naro Space Center by barge."
Yun Young-bin, administrator of the space agency who visited the Naro Space Center that day, said, "With the successful launches in 2022 and 2023, Korea became a country that can independently place satellites into desired orbits," adding, "This fourth launch is the first since the launch of the Korea AeroSpace Administration, and the starting point for moving from government-led to private-led efforts." He continued, "Through the fourth to sixth launches, we will secure the reliability of Nuri and, beyond raising our technical level, firmly build the foundation of the space industry," adding, "Based on successful launches, we will create a space industry ecosystem where the private sector can operate freely."