[Nuri's 5th Launch] 15 Satellites Set for 'Space Delivery' Every 35 Seconds, One Day to Go...Nuri Steps Closer to a Commercial Launch Vehicle

From One to Five Main Payloads, 1,071 kg of Satellites
The Most Complex Multi-Satellite Mission Yet
Considering Larger Fairing and Adapter, Costs Lowered by Repetitive Production
Beyond "Launch Success," Testing Service Competitiveness

On the 6th, the Nuri rocket is being transported to the launch pad at the Naro Space Center's integrated assembly building in Goheung, Jeollanam-do. Photo by the Korea Aerospace Research Institute

On the 6th, Nuri rocket is being transported to the launch pad at the Naro Space Center Assembly Building in Goheung, South Jeolla Province. Photo by the Korea Aerospace Research Institute

On the morning of October 6, just one day before its fifth space flight, the Korean launch vehicle Nuri was transported to the launch pad. Having proven its flight performance over four previous launches, Nuri now takes on a more complex mission: carrying the largest payload so far—15 satellites—into space and deploying them sequentially at designated times and in a specified order. This test marks Nuri's evolution from a launch vehicle capable of sending a single satellite into orbit to a "space transportation vehicle" tasked with precisely delivering multiple satellites to their targeted orbits.

From one primary payload satellite to five... More 'guests' on board

Five NeonSat small cluster satellites, numbered 2 to 6, are mounted on satellite adapters for the 5th Nuri rocket launch. The Nuri rocket will transport a total of 15 satellites into space in this launch, including 5 NeonSat satellites and 10 CubeSats. Provided by Korea Aerospace Research Institute

The most notable change in the fifth launch is that the number of '(satellite) guests' aboard Nuri has increased. In last year’s fourth launch, there was one primary payload satellite along with 12 CubeSats, totaling 13 satellites. This time, all five units of the NEONSAT (NeonSat) small satellite cluster, designated as satellites 2 to 6 and developed under the leadership of the KAIST Satellite Technology Research Center, are being deployed as primary payloads. In addition, 10 CubeSats, including the domestically developed E3 Tester-2 space verification platform, will be loaded. With a total of 15 satellites, this is the highest number of satellites Nuri has transported in a single launch. The total satellite payload weight has also increased from approximately 960 kg in the fourth launch to 1,071 kg this time. The target orbit is a sun-synchronous orbit at an altitude of about 570 km.

Once the third and final stage of Nuri reaches the target orbit, it will begin by sequentially deploying the five NeonSat 2–6 satellites. They will not be separated all at once; instead, one satellite is released, followed by a wait of about 35–40 seconds before the next satellite is deployed. The 35–40 second interval was determined through analysis of the flight trajectory, ensuring that each satellite can maintain sufficient distance from the next as they orbit. Hang Yeongmin, Director of the Space Launcher Research Institute at the Korea Aerospace Research Institute, explained: "Since 15 satellites are being launched, we do not have ample time," noting that these intervals are set to ensure that the separated satellites establish enough distance from one another while orbiting.

After releasing all five NeonSat satellites, the Nuri rocket’s third stage will change its orientation. It will then proceed to eject the remaining 10 CubeSats in pairs, repeating the process five times at 10-second intervals. Once all 15 satellites have been released, the rocket’s third stage will maneuver away to prevent the possibility of colliding with any previously deployed satellites that might have approached during their orbits.

In the continuous operation of separation, distance securing, attitude adjustment, further separation, and avoidance maneuvers, Nuri is demonstrating not only the capability to reach the target altitude but also its ability to safely deploy multiple satellites into their designated orbits—an essential operational competence for a next-generation launch vehicle.

The shock experienced during the separation process has also been reduced. For this launch, the Korea Aerospace Research Institute developed a low-shock satellite separation device specifically for small satellite clusters. This device is designed to firmly secure the satellites to the rocket during launch while minimizing the impact transmitted to the satellites during their release in space. Furthermore, a new lower ring has been applied to accommodate the sub-payload satellites such as CubeSats.

The ability to accurately transport and deploy multiple satellites at once is crucial for commercial launch services, as each customer requires a different number, size, and targeted orbit for their satellites. Tae seog Oh, Administrator of the Korea Aerospace Administration (KASA), stated at a Kwanhun Forum held on September 30, “The ability to launch various satellites into different orbits and altitudes is at the core of commercial launch services. Building up these capabilities is essential.”

After separation from Nuri, over 2–3 months, the five satellites form a 'formation flight'

Researchers at KAIST Satellite Technology Research Center are examining NeonSat, a microsatellite cluster to be loaded on the fifth flight of the Nuri rocket. Five units of NeonSat 2 to 6 were produced repetitively based on the same design through a mass production method. Provided by Korea Aerospace Research Institute

Nuri’s mission ends once the satellites are safely separated, but the NeonSat satellites’ mission only truly begins at that point. Immediately following the launch, all five satellites will orbit the Earth at relatively close distances. Then, by using each satellite’s thruster and managing their relative speeds, the satellites will gradually increase their separation and align their altitudes. Over the course of approximately two to three months, they will form a cluster, spaced about 71 degrees apart along the same orbital plane.

Lee Sanghyeon, Head of the Small Satellite Cluster Project at the KAIST Satellite Technology Research Center, explained, “Initially, the five satellites will be close together, but by adjusting their spacing and altitude using their thrusters and controlling relative velocities, they will gradually spread out. We anticipate it will take about two to three months for the five satellites to form the proper cluster with even spacing.”

The concept of "repetition" is also applied to the manufacturing process for the five satellites. Whereas previous national satellites were essentially custom-built one at a time, the NeonSat satellites adopted a mass production method, with the satellites being produced sequentially using the same design.

Director Lee mentioned, “Previously, it took two to three years to build a single satellite, but using mass production methods, one can be built in about two months. By optimizing test procedures, automating the testing process, and establishing a component supply system, production time has been significantly reduced.”

Repeated launches are essential for Nuri to become a truly commercial launch vehicle. Successful results from one or two launches do not guarantee reliability. The only way to increase the success rate and reduce potential variables in each phase is through repeated manufacturing, testing, and launching of vehicles with identical designs.

Since its first launch in 2021, Nuri has completed four flights. In the inaugural launch, a dummy satellite was lifted to the target altitude, but the third stage engine shut down earlier than anticipated, resulting in a failure to achieve orbit. In the second launch in 2022, for the first time, Nuri successfully inserted a satellite into its target orbit, followed by further demonstration launches for the third and fourth flights. The significance of this fifth launch, and the subsequent sixth and seventh scheduled launches, is that they aim to accumulate operational know-how for repeated running of the rocket after technical capabilities have been secured.

At the Naro Space Center Assembly Building in Goheung, Jeollanam-do, the integration work of the Nuri rocket No. 5’s first and second stages with the third stage is underway. The logos of the primary payload for the fifth launch, including the microconstellation satellite NEONSAT, are emblazoned on the fairing on the right. Provided by KAIST Advanced Institute of Science and Technology

Another reason why repeated launches are important is cost. During Nuri’s development phase, various measuring devices and sensors were installed on the rocket to monitor its status and performance during flight. As launches are repeated and sufficient flight data is gathered, these instruments will become less necessary and can be reduced. The more production and testing is repeated, the more standardization and efficiency can be achieved.

The ultimate goal for our government is to move “from a launch vehicle possessor nation to a launch service provider nation.” Even with improved payload capacity and precision for orbital deployment, it will be difficult to attract real launch demand if competitive pricing against foreign launchers is not achieved. That is why, alongside boosting reliability through repeated manufacturing and launches, it is also necessary to lower production, testing, and operational costs.

Jae Sung Park, Head of the Space Transportation Department at the Korea Aerospace Administration (KASA), took it a step further, distinguishing between “successful launch” and “launch service” as the next milestone for Nuri. He emphasized, “The difference between a ‘successful launch’ and a ‘launch service’ ultimately lies in achieving economic viability. It is vital not only to provide high reliability, but also a competitively low-cost and highly efficient service.”

This content was produced with the assistance of AI translation services.