Why Is the Nuri Rocket’s First Nighttime Launch Set for 1 a.m.? “You Must Board the ‘Space Train’ When the Door Briefly Opens” [Nuri Rocket 4th Launch]

Nuri Rocket to Launch at Night for the First Time on the 27th
Why the Launch is Set for "1 a.m."
Narrow Time Window for Precise Insertion into Sun-Synchronous Orbit
Concerns Over Upper Stage Space Debris Also Addressed

The main payload for the fourth launch of the Nuri rocket, the 'Next-Generation Medium Satellite 3,' along with 12 CubeSats as secondary payloads, was unveiled at a press briefing on November 14.

This launch, jointly conducted by Korea Aerospace Industries (KAI), the Korea Aerospace Research Institute, and various universities, companies, and research institutes, is regarded as a significant turning point in Korean space development, marking the shift from a government-led to a private sector-led approach. Notably, this will be the first nighttime launch in the history of the Nuri rocket.

On September 16, Nuriho was moved to the launch pad for the final test ahead of its fourth launch at Naro Space Center in Goheung County, Jeollanam-do. Provided by Korea Aerospace Research Institute. Photo by Yonhap News Agency

Dawn Launch Time Chosen to Match Sun-Synchronous Orbit

The fourth launch of the Nuri rocket is scheduled for around 1:00 a.m. (between 00:54 and 01:14) on November 27. The reason for this midnight launch time is to ensure that the main payload, the Next-Generation Medium Satellite 3, is precisely inserted into a Sun-synchronous orbit (SSO). The launch angle, timing, and flight trajectory of the Nuri rocket are all designed based on this main payload, and the 12 CubeSats will be deployed into a Sun-synchronous orbit at a similar altitude to the medium satellite.

The Sun-synchronous orbit is used for observation and scientific missions, maintaining a consistent trajectory relative to the Earth's rotation and the sun's altitude. Even a slight deviation in timing would prevent the satellite from matching the desired orbital plane.

On September 16, Nuriho stood on the launch pad for the final test ahead of its fourth launch at Naro Space Center in Goheung County, Jeollanam-do. Photo by Yonhap News

Kim Byoungseong, head of the Next-Generation Medium Satellite development at KAI, explained, "The key to the Sun-synchronous orbit is aligning the solar angle (solar incidence angle), which determines observation quality, and the exact orbital plane crossing is only possible at a specific time of day." He added, "The reason for this dawn launch is precisely due to these alignment requirements."

Researchers are conducting final inspections of the 'Next-Generation Medium Satellite 3' mounted on the third stage of the Nuri rocket and the CubeSat ejection tube at the Satellite Test Building of Naro Space Center, Korea Aerospace Research Institute, located in Goheung, Jeollanam-do. Provided by Korea Aerospace Research Institute

If the Sun-synchronous orbit is like a 'sky train route' that must pass by the sun at the same time every day, then only by matching the exact time can the 'space train' briefly open its doors for boarding.

Cho Sangbeom, Deputy Director of Launch Vehicle System Research Division 2 at the Korea Aerospace Research Institute, stated, "If the launch time is not precisely matched, the orbital plane will be misaligned, degrading the overall mission quality," adding, "There is virtually no technical flexibility in the launch time for this mission."

Launch Vehicle Preparation Status: "All Systems Normal"

Park Jongchan, Head of the Korean Launch Vehicle Advancement Project Group at the Korea Aerospace Research Institute, announced, "Preparation of the launch vehicle for the fourth Nuri launch is proceeding as planned."

Park explained, "We completed all propellant loading tests (WDR) by October, and although there was a high-pressure piping failure during testing, it was immediately repaired," adding, "There are currently no issues with the launch." He continued, "The research team has been working almost around the clock on assembly and inspections," emphasizing, "We will thoroughly prepare until the very end to ensure a successful launch."

All 13 Satellites Assembled Successfully... First Use of New Multi-Payload Adapter

The fourth Nuri launch will carry a total of 13 satellites: one Next-Generation Medium Satellite 3 and 12 CubeSats, the largest number of CubeSats ever launched by Nuri. To accommodate this, a new Multi-Payload Adapter (MPa) was introduced for this mission. This structure allows for the efficient arrangement of satellites of various sizes and weights, significantly enhancing Nuri's competitiveness in small satellite launches.

Jongchan Park, Head of the Korean Launch Vehicle Advancement Project Group at the Korea Aerospace Research Institute, is presenting at a press briefing on the 14th. Photo by Jounghwa Kim

Park stated, "Because we needed to carry a much more diverse set of satellites than in the third launch, the MPa was essential," adding, "To reduce the risk of separation failure, we designed multiple ejection ports instead of just one."

The Nuri rocket will separate all satellites approximately 15 minutes after launch. The Next-Generation Medium Satellite 3 will separate at 13 minutes and 27 seconds after launch, followed by the sequential deployment of the 12 CubeSats over about one minute. All separations will occur in the same direction as the flight path to minimize the risk of collision.

Park explained, "The ejection sequence was designed with orbital stability and safety as the top priorities," adding, "All satellites will be separated safely."

The Final Fate of the Launch Vehicle... "The Upper Stage Will Not Become Space Debris"

Questions were raised about whether the upper stage of the Nuri rocket would remain as space debris. Park stated, "The first and second stages will naturally fall into the ocean during flight," and "the third stage will continue to move in the same orbit as the satellites for a period, and its orbit will naturally decay over about 20 to 30 years." He added, "There will be no intentional explosion or orbital change."

According to international space debris mitigation guidelines, the upper stage of a launch vehicle should be removed from orbit or re-enter the atmosphere and burn up within 25 years after the end of its mission. Park's comments mean that, in line with international guidelines, the third stage of the Nuri rocket's fourth launch will remain at a similar altitude to the satellites, but its orbit will gradually decay, eventually re-entering the atmosphere and burning up, so it will not remain as debris in space.

The First Step Toward Private Sector-Led Space Development

Park emphasized that this launch is significant not only for its technical success but also for its role in transforming the industrial structure. He stated, "This is the first case of Hanwha Aerospace participating in launch operations, and with the involvement of various satellites developed by universities and startups, this marks the true beginning of the era of private sector-led launch services."

He concluded, "We will do our utmost until the very end to deliver good news from Naro Space Center at dawn on November 27."