③Crowded Space... Nuri Considers "Space Traffic" Before Launching [Reading Science]

Beyond Simple Distance from Crewed Spacecraft:

Approach Direction and Collision Probability Now Calculated

Fifth Launch Marks Granular Proximity Standards,

Expanding Launch Windows While Ensuring Safety

Editor's NoteThe Korean launch vehicle Nuriho is set to embark on its fifth space flight on October 7. After four previous launches in which Nuriho has proven its flight performance, this fifth launch will see the rocket undertake a more complex mission. It will carry 15 satellites into space simultaneously, the role of private entities has grown, and the safety standards surrounding the launch have become more stringent. Taking this fifth launch as an opportunity, The Asia Business Daily will present a three-part series exploring the changes Nuriho has undergone, its new mission, and the evolution of launch operations.

As space around Earth becomes increasingly crowded, it has become necessary to consider "traffic conditions" when planning rocket launches. Starting with the fifth launch of the Korean launch vehicle Nuriho, the proximity avoidance criteria will be subdivided. Instead of merely checking the distance from crewed spacecraft such as the International Space Station (ISS), the new approach will also account for approach direction and collision probability. This aims to maintain safety while more precisely assessing actual collision risks, thereby ensuring viable launch windows can be secured.

The Korean launch vehicle Nuriho was erected on the launch pad at Naro Space Center in Goheung, Jeollanam-do, ahead of its fourth launch on November 25 last year. Courtesy of Korea Aerospace Research Institute

According to the Korea Aerospace Research Institute, Nuriho analyzes potential proximity to crewed spacecraft orbiting before launch. If there is any possibility that the scheduled launch trajectory and the crewed spacecraft's orbit will bring them excessively close, launches are prohibited during those times.

For the first four launches, the basic avoidance standard was to maintain at least 200 km of distance from crewed spacecraft. However, solely judging collision risk by the minimum distance between two objects in space has its limitations.

The fifth launch further refines these standards. Attention is given separately to the distance along and perpendicular to the flight direction, and probabilistic calculations for collision risk are also used as supplementary criteria. The standard involves evaluating real approach risks, for example using a collision probability threshold of 0.0001% or less.

One reason for refining these criteria is to maximize the available "launch window." Restricting launches simply because objects come within a certain distance could require adjusting launch times even in situations where the actual risk of collision is extremely low. By jointly analyzing approach direction, relative trajectory, and collision probability, researchers explain that risk can be assessed with greater precision.

AI-generated image.

The launch time itself is not determined solely by the readiness of the launch vehicle. It is set through consideration of the target orbit, mission of the payload satellites, weather around the launch site, as well as the potential for approaching other space objects. For the fifth launch of Nuriho, the scheduled window runs from 12:23 p.m. to 1:23 p.m. on October 7, with the final time to be determined based on day-of conditions.

The ability to meet the designated launch window is also directly connected to reliability for repeated launches. Tae seog Oh, Administrator of the Korea Aerospace Administration (KASA), said at a press forum on September 30 regarding Nuriho's fifth launch, "We will work to swiftly resolve any issues and launch at the scheduled time to further build our credibility."

Collision avoidance continues even after reaching orbit. This time, Nuriho will carry a total of 15 satellites—five microsatellite clusters and 10 CubeSats. The third stage of Nuriho will sequentially deploy these satellites, then perform maneuvering operations to avoid any further close approaches to its deployed satellites.

After the fourth launch of Nuriho on November 27 last year, researchers from the Korea Aerospace Research Institute checked the flight status and orbital information of Nuriho at the Launch Control Center (LCC) of Naro Space Center in Goheung, Jeonnam. Provided by KARI

Prior to launch, proximity to objects already orbiting the Earth must be evaluated, and after reaching the target orbit, collision prevention measures must consider the newly separated satellites. As missions involving the transport of multiple satellites increase, precision in orbital insertion, satellite separation, and collision avoidance has become ever more vital for launcher operations.

This operational knowhow will not be limited to Nuriho alone. The experience accumulated through repeated launches—covering launch vehicle manufacturing, integration, testing, and operations—can be leveraged for the development of next-generation launchers in the future.

Jaeseong Park, Director of Space Transportation at KASA, said, "Operational experience in quality control, manufacture and assembly, testing, and launch operations gained through repeated launches can be utilized in establishing reusable and multiple-launch systems for next-generation launch vehicles."

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