Opened the Path to Space... Meaning and Prospects of Success? [Nuriho 2nd Launch]

The Korean launch vehicle Nuriho (KSLV-II), designed and manufactured entirely with domestic technology, is soaring into space with flames erupting from the launch pad at Naro Space Center in Goheung-gun, Jeollanam-do on the 21st. Unlike the first launch, which carried only a dummy satellite with no actual functionality, the second launch of Nuriho this time included a performance verification satellite and four CubeSats. / Goheung = Photo by Joint Press Corps

[Asia Economy Reporter Kim Bong-su] "The door to space has opened."

South Korea's first independently developed space launch vehicle, Nuriho, successfully completed its second launch on the afternoon of the 21st. This was a remarkable achievement that erased the disappointment from the first launch on October 21 last year, which, despite a perfect flight, failed to insert the satellite mock-up into orbit, leaving the mission incomplete. With this success, South Korea has joined the ranks of the "world's top seven space powers." It has become the seventh country capable of launching practical satellites weighing over 1 ton into space, thus acquiring a full-fledged means for space exploration.

◇ Nuriho, an Essential Item for the Space Exploration Era

During the Cold War era, the United States and the Soviet Union competed in rocket development, satellite launches, and lunar exploration, but these efforts mainly had significance in intercontinental ballistic missile (ICBM) weapon technology development, intelligence, communication, and national defense and security. Although the U.S. conducted the Apollo project, achieving humanity's first manned lunar landing, it gained little tangible benefit. Since the 2000s, the situation has changed. Numerous private companies have emerged, aiming to gain economic benefits through space exploration using advanced technology. Elon Musk's SpaceX and Jeff Bezos's Blue Origin are representative examples. Earth's resource depletion and environmental destruction have also broadened the horizon for space exploration. The U.S. Artemis project, which involves lunar exploration, base construction, and terminal (Lunar Gateway) establishment, is driven by these reasons. China and Russia have formed a bloc through joint lunar exploration and space station construction in response. South Korea had little presence until now. Although it gained recognition for communication and observation satellite manufacturing technology through its own satellite development starting in the 1990s, its position in the international space development cooperation system was limited due to the absence of an independent space launch vehicle.

Especially as space has become an essential area in the era of the Fourth Industrial Revolution's advanced technologies, competition among countries has intensified. Next-generation mobile communication technology such as 6G, autonomous vehicles, unmanned drones and robot delivery, urban air mobility (UAM), and space internet all require ultra-high-speed communication, internet satellites, and satellite navigation systems (GPS), making space indispensable. SpaceX's Starlink space internet network was notably used to replace ground networks during the Ukraine war, aiding attacks against Russia. Now, for building advanced technology and industries and ensuring national security, the ability to launch satellites at desired times and scales using a country's own launch vehicle has become essential. Satellites are also actively used for environmental purposes such as information acquisition and climate observation to combat global warming, as well as for resource, agriculture, fisheries, and land management. Furthermore, national security demands have arisen to counter threats from space debris and asteroids and to prepare for potential attacks from hostile countries in space. Efforts to secure energy through space solar power plants, space mineral exploration, mining, transportation, and expanding humanity's foothold through lunar and Mars exploration are also actively pursued, providing grounds for securing space development means.

Only nine countries worldwide have been able to launch space launch vehicles independently: Russia, the United States, Europe, China, Japan, India, Israel, Iran, and North Korea. Among these, Israel, Iran, and North Korea are evaluated to have payload capacities under 300 kg. With Nuriho's success, South Korea secured a 1.5-ton payload capacity, becoming the seventh country capable of launching practical satellites over 1 ton.

The Korean launch vehicle Nuriho (KSLV-II), designed and manufactured entirely with domestic technology, is soaring into space with flames erupting from the launch pad at Naro Space Center in Goheung-gun, Jeollanam-do on the 21st. Unlike the first launch, which carried only a dummy satellite with no actual functionality, the second launch of Nuriho this time included a performance verification satellite and four CubeSats. / Goheung = Photo by Joint Press Corps

◇ South Korea's 'Domestic Technology' Achievement After 30 Years

Since the 1990s, South Korea has acquired launch vehicle technology and experience through the scientific rocket series and Naroho development, successfully independently developing Nuriho based on this foundation. In October 1993, it successfully launched the single-stage solid scientific rocket KSR-I, and in June 1998, the two-stage solid scientific rocket KSR-II was successfully launched. In February 2003, the first liquid-propellant scientific rocket KSR-III was successfully launched. Particularly, in April 2013, South Korea made a significant leap in launch vehicle technology by successfully launching Naroho (KSLV-I). After two failures in August 2009 and June 2010, the third launch barely succeeded. Naroho was not a truly Korean launch vehicle as it used a first-stage engine imported from Russia and only the second stage was developed domestically with a 7-ton engine.

However, the Korea Aerospace Research Institute (KARI) succeeded in independently producing a 30-ton liquid engine in 2005 using technology acquired during Naroho's development. Based on this, development of a 75-ton liquid engine began in 2010, and by November 2018, a successful test launch secured the technology. The 75-ton liquid engine developed is clustered in fours on Nuriho's first stage, producing a total thrust of 300 tons. One engine is also used on the second stage. During the first launch on October 21 last year, both the first and second stages operated normally, increasing reliability. With the success of Nuriho's second launch, South Korea has completed the 30-year history of space launch vehicle development that began in 1993 with a crowning achievement. Notably, all technologies from A to Z in space launch vehicle development?including engines, propellant tanks, fairing separation, and launch pad construction and operation?were independently researched and developed by KARI and over 300 private companies, marking a significant 'domestication' achievement. Globally, very few countries have independently developed space launch vehicles with domestic technology. Russia and the U.S. initially acquired German V2 rocket technology for reference. Latecomers like China and Japan almost entirely received technology transfers from the U.S. and Russia, making their development far from independent.

Nuriho's development faced many twists and turns. Officially started in 2010 amid cold external and internal views due to repeated failures of its predecessor, Naroho, there were no experienced liquid rocket engine developers initially. The team, mainly composed of those with experience in aircraft gas turbine engine development, secured basic technology by researching foreign libraries and museums. Developing the turbo pump, the most critical component, was especially challenging. It required ultra-precision technology to precisely control hundreds of valves to evenly distribute fuel and oxidizer. Despite setbacks including an explosion accident in 2007, the technology was secured in 2008. Even after scaling up to the 75-ton engine, many hurdles remained. From early 2017, unstable combustion occurred for about six months, causing strong engine vibrations. The research team repeatedly redesigned, replaced parts, and experimented by changing fuel and oxidizer mixture ratios. Clustering four 75-ton engines into one first-stage propulsion system was also difficult. This 'clustering' technology requires all four engines to be precisely aligned and produce identical thrust for the rocket to fly on the intended trajectory. Though it sounds simple, it is highly technically challenging and considered one of the biggest hurdles in space launch vehicle development.

The first launch on October 21 last year was a "partial success." The first and second-stage engines operated normally, and all flight events including stage and fairing separation proceeded correctly. However, the third stage's 7-ton liquid engine failed to burn for the targeted 521 seconds, shutting down prematurely after 475 seconds (46 seconds early). As a result, although reaching the target altitude of 700 km, it failed to maintain the required speed of 7.5 km/s, causing the 1.5-ton satellite mock-up to fail orbit insertion. KARI and technical teams investigated and confirmed that the helium tank fixing device on the third-stage engine loosened, causing a crack in the oxidizer tank. Technical improvements were implemented, including reinforcing the helium tank's lower fixing part and thickening the oxidizer tank manhole cover.

The second launch was initially scheduled for the 15th but was postponed to the 16th due to strong winds, then delayed again to the 21st after a sensor anomaly was detected. During inspection on the 15th, an abnormality was found in the oxidizer tank filling amount measurement sensor on the first stage. Nuriho, which was on the launch pad, was taken down and transported to the assembly building for urgent inspection. Fortunately, the problem was resolved by replacing the sensor's core component without requiring the time-consuming separation of the first and second stages, and the launch on the 21st was successfully conducted.

The Korean launch vehicle Nuriho (KSLV-II), designed and manufactured entirely with domestic technology, is soaring into space with flames erupting from the launch pad at Naro Space Center in Goheung-gun, Jeollanam-do on the 21st. Unlike the first launch, which carried only a dummy satellite with no actual functionality, the second launch of Nuriho this time included a performance verification satellite and four CubeSats. / Goheung = Photo by Joint Press Corps

◇ What’s Different in the Second Launch?

The significance lies in launching an actual satellite using a domestically made launch vehicle for the first time. During the first launch, only a satellite mock-up was onboard for safety reasons, but this time, a functioning performance verification satellite and a satellite mock-up were simultaneously loaded on Nuriho and successfully placed into a 700 km orbit. The performance verification satellite, developed by the Korea Atomic Energy Research Institute, is equipped with a lunar exploration heat-generating battery, high-speed attitude control actuators essential for spacecraft and satellites, space communication antennas, video shooting and transmission devices, and will undergo experiments and technology verification. Additionally, four CubeSats developed by Chosun University, Seoul National University, Yonsei University, and KAIST are housed within the performance verification satellite and will be sequentially deployed one by one starting two days after orbit insertion to begin activities in orbit.

◇ Nuriho is the 'Primer'

The 2 trillion won Nuriho project will conclude with this second launch but is expected to lay the foundation for South Korea's independent space exploration. The government plans to continue verifying and upgrading Nuriho's performance and increase reliability by conducting four more launches in the future. In 2023, a mission will be undertaken to place the second next-generation small satellite into orbit. In 2024, 2026, and 2027, repeated launches will verify reliability and place the first ultra-small satellite into orbit. The government also plans to invest an additional approximately 3 trillion won to develop next-generation launch vehicles. A preliminary feasibility study is underway to significantly upgrade Nuriho's performance to compete in the international space launch vehicle market and to utilize it for deep space exploration such as lunar, Mars, and asteroid missions.

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