15 Minutes of Tension... Will Nuriho Succeed This Time? [Nuriho 2nd Launch]

Preview of the Second Launch Site
Focus on the Performance Verification Satellite
Role as a Catalyst for Independent Space Development

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] On the 15th, Korea's first indigenous space launch vehicle, Nuriho (KSLV-II), will be launched. We examine how it differs from the 2013 Naroho and how the second launch will proceed. Nuriho is expected to serve as a 'primer' for Korea's independent space exploration and the activation of the private space industry in the New Space era, as well as for international space cooperation.

◇ Differences between Nuriho and Naroho?

In 2013, Korea successfully launched the Naroho (KSLV-I), a space launch vehicle developed in collaboration with Russia. The project cost a total of 520.5 billion KRW, and after two failed attempts in 2009 and 2010, it succeeded on the third try by reaching the target altitude of 300 km and separating the fairing. Naroho was a two-stage vehicle: the first stage had a 170-ton thrust liquid engine, and the second stage had a 7-ton thrust solid engine. It was a small launch vehicle with a total weight of 140 tons, payload capacity of 100 kg, total length of 33.5 m, and maximum diameter of 2.9 m. However, Naroho was not a 'domestically produced launch vehicle' because its first-stage engine was imported from Russia.

In contrast, Nuriho was entirely manufactured domestically, with all components and structures of the first, second, and third stages produced using Korean technology, completing it purely with indigenous technology. After developing a 30-ton liquid engine based on technology acquired during the Naroho project with Russia, Korea succeeded over more than ten years since 2010 in producing a 75-ton medium-to-large liquid engine. Engine clustering, large propellant tanks, payload fairings, advanced launch pads, and operation systems were all independently designed and manufactured. Nuriho is a medium-sized launch vehicle with a payload capacity of 1.5 tons, much larger than Naroho. It weighs about 200 tons, measures 47.2 m in length, and has a maximum diameter of 3.5 m. The first stage clusters four 75-ton engines to produce 300 tons of thrust, the second stage has one 75-ton liquid engine, and the third stage consists of one 7-ton liquid engine. The budget was also much larger than Naroho’s, with 1.9572 trillion KRW invested over ten years.

The Korean launch vehicle Nuriho (KSLV-II) is soaring powerfully, emitting flames at the second launch pad of Naro Space Center in Goheung-gun on the 21st. Nuriho is a three-stage launch vehicle designed to deploy a 1.5-ton class practical satellite into low Earth orbit (600?800 km). It is the first domestically produced launch vehicle completed entirely with domestic technology, from engine design to manufacturing, testing, and launch operation. / Goheung = Photo by Joint Press Corps

◇ Preview of the Second Launch

Nuriho will be launched on the 15th from 508 Habanno, Bongrae-myeon, Goheung-gun, Jeollanam-do, specifically from the second launch pad at Naro Island’s Naro Space Center. The launch is scheduled to take place between 3 PM and 7 PM if possible. However, the final launch time will be determined based on weather conditions such as wind speed, clouds, lightning over Naro Island, and the possibility of collision with space objects. If delayed, a one-week backup period starting the next day is set. Currently, Nuriho, fully assembled at the Naro Space Center’s comprehensive assembly building, will be transported to the launch pad a day before using a transporter, then erected vertically and fixed on the launch pad. Afterward, an umbilical cable, which functions similarly to an umbilical cord, will be connected for comprehensive checks of fuel and electrical systems. Fuel and oxidizer will be loaded starting four hours before launch, and if the final inspection shows no issues, the countdown and automatic launch operation will begin 10 minutes before launch. At launch time, the first stage’s 300-ton class engine (four 75-ton engines) will ignite and the hold-down clamps will release. A few seconds later, once sufficient thrust is generated, the vehicle will lift off, and the umbilical plate connected to the launch pad will separate. About 127 seconds after liftoff, at an altitude of 57 km, the first stage will separate if conditions are met. At 233 seconds and 191 km altitude, the fairing will separate, and at 274 seconds and 258 km altitude, the second stage will separate. Notably, about 15 minutes after launch, exactly 897 seconds, the performance verification satellite will be released at the target altitude of 700 km, followed by the satellite mock-up about 70 seconds later. If all proceeds normally, the Korea Aerospace Research Institute (KARI) technical team will analyze data about 30 minutes later and officially declare the launch a success. During the first launch on October 21 last year, all processes up to reaching the target altitude proceeded normally, but the third stage engine malfunctioned and shut down 46 seconds earlier than planned, causing the satellite mock-up to fail to gain momentum and enter orbit, resulting in a 'partial success.'

The launch is overseen from the Launch Control Center (MDC) inside the Naro Space Center. To track the launched Nuriho, tracking radars and telemetry antennas are installed and operated at the Naro Space Center and Jeju Island. Tracking during the latter part of the flight is handled by telemetry antennas installed in Palau, Philippines. Especially at the Naro Space Center, tracking radars capable of tracking the launch vehicle up to 3,000 km and telemetry equipment that can monitor flight trajectory and operational status up to 2,000 km are operated. Nuriho will fly approximately 100 km away from Jeju Island and Japan’s Fukuejima. The first stage is expected to fall about 413 km from the launch site, the second stage about 2,800 km away, and the fairing about 1,514 km offshore.

On the launch day, land within a 3 km radius centered on the Nuriho launch pad will be restricted. At sea, all vessels will be prohibited from entering a 24 km wide and 78 km long area along the flight path. In the air, a no-fly zone 44 km wide and 95 km long will be established along the flight direction.

◇ Performance Verification Satellite Also 'In the Spotlight'

During this second Nuriho launch, a performance verification satellite weighing about 200 kg and a 1.3-ton satellite mock-up will be loaded into the payload and placed into orbit. The performance verification satellite will not only serve as a payload but also conduct various scientific experiments and performance verifications. It carries a thermal battery (ETG) developed by the Korea Atomic Energy Research Institute, weighing less than 1 kg and measuring only 85 mm in diameter and 125 mm in height. This cutting-edge product generates electricity using temperature differences and is planned for use in future lunar landing explorations. Additionally, a control moment gyro (CMG) developed by the private company JusTech is installed for performance verification. This device is essential for attitude control of space launch vehicles such as satellites and probes and has been selected as a task under Korea’s core space technology development project. An S-band antenna for communication between the satellite and ground stations will also be performance-verified. This is another essential technology under the core space technology development project. Other equipment includes a CubeSat deployer and a Video Capture System (VCS) for imaging and transmission.

The CubeSats housed inside the performance verification satellite, which will be sequentially ejected later, are also of interest. They include Korea’s first multi-band Earth observation satellite (STEP Cube Lab-II) with electro-optical, mid-infrared, and long-infrared sensors developed by Chosun University; 'SNUGLITE-II,' a satellite from Seoul National University for Earth observation using precise satellite navigation system (GPS) carrier phase signals for GPS Radio Occultation data collection; KAIST’s hyperspectral camera Earth observation satellite RANDEV; and Yonsei University’s fine dust monitoring satellite MIMAN. These CubeSats will be sequentially ejected from the performance verification satellite starting on the 23rd at two-day intervals to begin their missions.

◇ Nuriho as a 'Primer'

The 2 trillion KRW Nuriho project will conclude with the first and second launches but serves as a primer for 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, marking the first commercial use of Korea’s launch vehicle. Further launches are planned in 2024, 2026, and 2027 to verify reliability, with plans to place the first ultra-small satellite into orbit.

Moreover, the government plans to invest an additional approximately 2 trillion KRW to significantly upgrade Nuriho’s performance. To compete in the international space launch vehicle market and enable deep space exploration such as lunar, Mars, and asteroid missions, a preliminary feasibility study is underway. According to plans released last month, the next-generation launch vehicle succeeding Nuriho will be developed with advanced technology for multiple reuses. This will save resources and costs and enhance competitiveness in the launch vehicle market. It will be developed as a two-stage vehicle using liquid oxygen-kerosene. The first stage engine will cluster five 100-ton class staged combustion cycle liquid engines. Technologies for reusable launch vehicles such as reignition and thrust control will be applied. The second stage engine will consist of two 10-ton class staged combustion cycle liquid engines equipped with multiple reignition and thrust control functions. Specifically, it will be capable of sending 1.8-ton lunar transfer orbit probes and 1.0-ton Mars transfer orbit probes into space. The next-generation launch vehicle will be used for lunar landing probes planned after 2030.

A KARI official stated, "Through the Korean launch vehicle advancement project, we will accumulate reliability, nurture and support domestic industries, and expand space transportation capabilities through continuous advancement of Korean launch vehicle technology. We will discover and foster system integration companies domestically and ensure that participating companies grow together to establish a self-sustaining industrial ecosystem in Korea."