②One Satellite Every 35-40 Seconds...Nuri Takes on the Challenge of 'Precision Separation' of 15 Satellites [Nuriho, Beyond Launch]

Sequential Separation of Five Cluster Satellites Followed by Deployment of Ten CubeSats
Attitude Adjustments to Prevent Collisions... Five Satellites to Form Complete Cluster in Two to Three Months

Editor's NoteThe Korean space launch vehicle Nuri is set for its fifth space flight on October 7. After proving its flight performance through four launches, Nuri will take on a more complex mission with this fifth launch. It will carry 15 satellites into space at once, the role of the private sector has expanded, and the safety standards surrounding the launch have become even more rigorous. The Asia Business Daily will examine the changes the Nuri rocket has brought, its new and challenging missions, and the evolved launch operations in a three-part series taking the fifth launch as a milestone.

Researchers are performing the integration of the first and second stages with the third stage of the Nuri rocket at the Vehicle Assembly Building of Naro Space Center, Korea Aerospace Research Institute in Goheung, Jeonnam. Provided by the Korea Aerospace Research Institute

When the Korean launch vehicle Nuri reaches space on October 7, another intricate mission will begin. It will have to safely deploy all 15 satellites it has carried, one by one, in a predetermined order and at set times. The five microsatellite cluster satellites will be sequentially separated at intervals of 35 to 40 seconds, followed by ejection of the 10 CubeSats in turn. This task, called "precision separation," involves even adjusting Nuri's attitude to ensure that the previously deployed satellites, the trailing satellites, and the launch vehicle itself do not collide.

The primary payloads for Nuri's fifth launch are five units of the microsatellite cluster "NEONSAT" Nos. 2 to 6, developed by the Satellite Technology Research Center at the Korea Advanced Institute of Science and Technology (KAIST). Alongside, 10 CubeSats will be launched—including the E3 Tester-2, a Korean-made space verification platform for locally developed components.

When Nuri reaches its target orbit, it will first separate the five NEONSAT satellites one by one. The time interval between satellites will be approximately 35 to 40 seconds.

This interval was not set arbitrarily. It was determined after analyzing whether the previously separated satellite and the next one could sufficiently distance themselves in orbit. However, the interval cannot simply be extended. All 15 satellites must be deployed into space within a limited timeframe.

Han Youngmin, Director of the Space Launch Vehicle Directorate at the Korea Aerospace Research Institute (KARI), explained, "Since we are launching 15 satellites, there is not enough time," and indicated that the deployment interval was set to ensure that the separated satellites can secure enough distance from each other as they orbit.

When deploying the satellites, the attitude of Nuri's third stage is also adjusted. After the sequential separation of the five NEONSAT satellites, the 10 CubeSats are ejected in pairs at 10-second intervals. After completing the separation of all satellites, Nuri's third stage performs avoidance maneuvers to prevent it from approaching the satellites again.

A new separation device will also be introduced. For this launch, KARI has developed a low-shock separation device for the microsatellite cluster satellites. This device minimizes the shock transmitted when the satellite is detached from the launch vehicle in orbit, after having been held securely in place until that moment. Additionally, a new lower ring has been applied to accommodate the auxiliary payloads.

Although Nuri's role ends as soon as the satellites are deployed, that's when the cluster formation of NEONSAT begins.

Immediately after launch, the five satellites travel along similar orbits at relatively close distances. Then, by using each satellite's thruster and adjusting relative velocity, they gradually increase separation distances and align altitude. Ultimately, the satellites will form a cluster spaced approximately 71 degrees apart on the same orbital plane. It is expected to take about two to three months to achieve a complete cluster formation.

Lee Sanghyun, project manager for the microsatellite cluster at KAIST Satellite Technology Research Center, explained at a recent payload briefing, "Initially, the five satellites are relatively close, but by using the thrusters and adjusting relative speeds, separation distances will gradually increase and altitude will be adjusted," adding, "We expect it will take about two to three months for the five satellites to form a cluster at regular intervals."

The method for manufacturing multiple satellites at once has also changed. Whereas traditional national satellites were typically built one at a time by special order, NEONSAT has adopted a mass-production approach, repeatedly manufacturing satellites with the same design.

Five ultra-small cluster satellites NEONSAT 2 to 6, which will be onboard the fifth Nuri rocket launch, are preparing for launch at Naro Space Center in Goheung, South Jeolla Province. After launch, the five satellites will form a cluster with equal spacing on the same orbital plane over about two to three months. The Nuri rocket fairing is visible in the background. Courtesy of the Korea Aerospace Research Institute

Lee noted, "Previously, it took two to three years to manufacture a single satellite, but with mass production, each unit now takes about two months," adding, "By optimizing test procedures, automating tests, and establishing stable parts procurement, we have significantly reduced production time."

From Nuri's perspective, this mission is far more complex than simply placing a single satellite into its target orbit. The rocket must carry several satellites at once and then safely separate them in the correct sequence and intervals during actual flight.

Park Jaeseong, Director of Space Transportation at the Korea Aerospace Administration (KASA), said, "Deploying multiple satellites into their target orbits will enhance Nuri's operational capabilities to a new level."

Tae seog Oh, Administrator of the Korea Aerospace Administration, emphasized at a Kwanhun Forum on September 30, "Launching various satellites into various altitudes is the key to commercial launch services, and we must continue to build this capability."

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