The fourth launch of the Korean launch vehicle Nuri (KSLV-II) is one day away. Unlike the third launch, this one is overseen throughout the entire process, from manufacture to assembly, by Hanwha Aerospace, the system integrator corporations. It is seen as an inflection point where the development of the Korean launch vehicle is shifting in earnest from the research and development stage to industrialization. In particular, Nuri will for the first time carry 13 satellites simultaneously, making the technical significance great as it verifies multi-payload capability.
The Korea AeroSpace Administration and the Korea Aerospace Research Institute (KARI) have scheduled Nuri's fourth launch for about 12:55 a.m. on the 27th. The reason the launch time is set around midnight is that the primary payload, the next-generation mid-size satellite No. 3, must go up at a time with little solar interference to conduct aurora and airglow observations.
On the morning of the 25th, Nuri was loaded onto an unmanned special transport vehicle, the "transporter," and moved from the assembly building to launch pad No. 2. After about an hour of transport, Nuri completed its erection work at the pad, followed by umbilical (umbilical) consolidation and launch vehicle signal checks, with key preparations proceeding without issues.
On the 26th, one day before the launch, core factors that determine whether the launch succeeds will be reviewed comprehensively. The first is flight safety, which analyzes whether Nuri's flight path after liftoff could collide with space objects or crewed spacecraft. If a collision risk is identified, the launch can be postponed immediately.
The second is weather conditions. The surface temperature must be between minus 10 degrees and 35 degrees Celsius, and if the average surface wind speed is 15 m/s or higher or the maximum instantaneous wind speed exceeds 21 m/s, the launch must be delayed. Some preparation steps were previously delayed due to adverse weather, including a strong wind advisory. Upper-level winds, the possibility of lightning, and space weather such as sunspots and solar particle activity are also cited as important variables.
Once the Launch Management Committee convening on the afternoon of the 26th finalizes whether to launch and the time by reflecting all these factors, preparations will begin about four hours before launch to load fuel (kerosene) and oxidizer (liquid oxygen. Once all preparations, including fuel loading, are complete, the prelaunch automatic operation (PLO) program will run starting 10 minutes before launch. If an unexpected issue is detected during the PLO segment, the launch will be automatically aborted. If a problem forces a postponement, a new launch date will be set between the 27th and Dec. 4, the launch reserve period.
After liftoff at about 12:55 a.m. on the 27th, each stage sequence must proceed as planned. The schedule—including first and second stage separation, fairing separation, and third-stage ignition—must line up precisely, and the final success will be determined by whether all 13 satellites are inserted exactly into their planned orbits.
Nuri will fly for a total of 21 minutes and 24 seconds after launch. At 2 minutes and 5 seconds after liftoff, stage one will separate at an altitude of 63.4 kilometers, and 3 minutes and 54 seconds later, the fairing will open and separate at an altitude of 201.9 kilometers. After 4 minutes and 32 seconds, the second stage will separate at an altitude of 257.8 kilometers and the third-stage engine will ignite.
The primary mission of this launch is to insert the next-generation mid-size satellite No. 3, developed by Korea Aerospace Industries (KAI), into a 600-kilometer sun-synchronous orbit. This satellite will separate first, 13 minutes and 27 seconds after launch. The remaining 12 CubeSats will then separate in pairs at about 20-second intervals. The CubeSats were built by Space LiinTech, HANCOM InSpace, the Electronics and Telecommunications Research Institute (ETRI), UZurotech, Quaternion, Seoul National University, Inha University, KAIST, Sejong University, the Korea Aerospace Research Institute (KARI), and CosmoWorks.
For flight safety, Nuri will fly toward the southern sea. The first stage will fall west of Kyushu, Japan, 428 kilometers from Goheung, South Jeolla Province, and the second stage will fall in waters east of the Philippines, 2,804 kilometers away.
Tracking of Nuri will be conducted with radar and telemetry (remote data reception equipment) installed at the Naro Space Center and the Jeju tracking station. The tracking radar can monitor Nuri's status up to 3,000 kilometers, and telemetry up to 2,000 kilometers. The latter phase of the flight will be handled by a tracking station KARI built in Palau, a Pacific island nation.
Whether the launch ultimately succeeds will be announced at 2:20 a.m. on the 27th, one hour and 25 minutes after liftoff. In particular, the moment 15 minutes and 27 seconds after launch, when the last CubeSat separates, is expected to be the key point that effectively determines whether the mission succeeds.