The Korean launch vehicle Nuri (KSLV-II) succeeded in its fourth flight, setting another milestone in Korea's space development history. The launch is significant as the first successful case in which the system integrator Hanwha Aerospace took responsibility from manufacturing to assembly, and as Nuri's first launch carrying 13 satellites at once.
The Korea AeroSpace Administration and the Korea Aerospace Research Institute (KARI) held a briefing at 2:40 a.m. on the 27th at the Naro Space Center in Goheung, South Jeolla, and officially announced that Nuri's fourth launch was completed normally.
Korea AeroSpace Administration Administrator Yoon Young-bin said, "It was an opportunity to raise Nuri's reliability and again prove Korea's capability to autonomously pioneer space."
◇ Launch delayed 18 minutes due to umbilical sensor anomaly
Nuri lifted off at 1:13 a.m. that day. The original target time was 12:55 a.m., but the launch was delayed 18 minutes due to an anomaly signal from a sensor on the umbilical tower. The umbilical tower is a connection device that supplies power, fuel, coolant and more to the launch vehicle, supporting it until just before liftoff and supplying necessary resources.
Park Jong-chan, Director General of KARI's Korea Launch Vehicle Advancement Program, explained, "Some sensors connected to the equipment that secures Nuri did not operate properly, so time was needed for verification." On-site checks confirmed that the actual securing equipment was normal and that the issue was limited to the sensor, so the launch preparations proceeded as planned.
Behind the 1:13 a.m. launch time is the concept of a launch window. A launch window is the "available time period" during which a launch vehicle can accurately reach its target orbit. It is determined by various factors, including Earth's rotation, the position of the target satellite orbit, and launch vehicle performance. Nuri's launch window this time was from 12:54 a.m. to 1:14 a.m.
Park said, "We reviewed the time at which preparations could be most stably completed within the launch window," adding, "We chose 1:13 a.m., just before the end of the launch window, to buy as much inspection time as possible."
◇ Stable initial flight and stage-by-stage separation
Nuri ascended stably immediately after liftoff, with first-stage separation occurring about 2 minutes 2 seconds after launch at an altitude of 65.7 kilometers, and the fairing (satellite shroud) opening and separating at an altitude of 211.1 kilometers at 3 minutes 50 seconds. After 4 minutes 23 seconds, the second stage separated at an altitude of 263.1 kilometers and the third-stage engine ignited.
However, the post-launch sequence progressed somewhat faster than the speed predicted by the research team. The originally expected flight end time was about 21 minutes, but the flight ended about 18 minutes after liftoff.
Regarding this, Park explained, "The actual performance of Nuri's first-, second- and third-stage engines was better than expected, so major events were achieved more quickly," adding, "Shutdown also occurred sooner."
The core of this flight was to place the primary payload, the third next-generation mid-size satellite, into its target orbit. The satellite separated successfully about 13 minutes 11 seconds after launch at a target altitude of 601.3 kilometers, and later at 1:55 a.m. successfully communicated with the ground station at King Sejong Station in Antarctica. The space agency confirmed the satellite's status, including the deployment of its solar panels, through the initial contact with the third next-generation mid-size satellite.
Going forward, the space agency plans to closely verify the satellite's condition through communications with KARI's ground station in Daejeon, King Sejong Station in Antarctica, and an overseas ground station in Svalbard, Norway. Communications with KARI's ground station are scheduled for about 2:39 a.m. and 11:57 a.m. on the 27th, and 14 passes with the overseas ground station are planned during the morning of the 27th.
The remaining 12 CubeSats were also deployed in the set order from 13 minutes 34 seconds to 15 minutes 14 seconds after launch. The final flight altitude was 601.3 kilometers, meeting the success criteria for this launch of 565 to 635 kilometers. KARI plans to verify their status through subsequent communications.
◇ First success under Hanwha's lead… full-fledged shift to private-led launch vehicle development
This launch is also the first success carried out with Hanwha Aerospace in charge of launch vehicle manufacturing and assembly. Hanwha Aerospace plans to conduct two more Nuri launches with KARI by 2027.
Park, the Director General, said, "From the fifth and sixth launches, Hanwha Aerospace will be more deeply involved in launch operations," adding, "The actual number of participants will increase, and Hanwha employees are expected to take the lead in operating the launch operations console."
Son Jae-il, CEO of Hanwha Aerospace, said, "There was a 2-year, 6-month gap between the third and fourth launches, which made it difficult to maintain the space industry ecosystem, but we overcame it together with our partners," adding, "Because space technology underpins all fields, including new materials, artificial intelligence (AI), communications and national security, we will do our best to advance launch vehicle technology."
Meanwhile, Administrator Yoon Young-bin said of future plans, "We will complete the sixth Nuri launch by 2027 and prepare for the seventh from 2028," adding, "With that in mind, we are planning next year's budget, and from the eighth launch onward, we aim to launch Nuri at least once a year."
Bae Kyung-hoon, Deputy Prime Minister and Minister of the Ministry of Science and ICT, also visited the launch site, saying, "This success again showed that Korea has secured independent space transportation capability," adding, "As a public-private joint launch carried out by the government, the private sector and national research institutes as one team, it marks a shift in Korea's space ecosystem from government-led to private-led."
She added, "Building on today's success, we will steadfastly push ahead on the path to becoming a space power, including developing next-generation launch vehicles, exploring the moon and deep space exploration."