"Why Didn't the Dummy Satellite Completely Melt?"... Nuriho, ICBM Test Rumor Controversy [Reading Science]

[Image source=Yonhap News]

[Asia Economy Reporter Kim Bong-su] On the 21st, suspicions arose that the launch of the Korean-type space launch vehicle 'Nuriho' was actually an intercontinental ballistic missile (ICBM) test. However, the Korea Aerospace Research Institute (KARI), which oversaw the launch, dismissed these claims as "nonsense."

▲ Why didn't the satellite mock-up burn up?

In this launch, Nuriho showed a flight trajectory similar to that of an ICBM. It was launched precisely at 5 p.m. and, after passing over the Naro Space Center, turned directly south and ascended to an altitude of 700 km. Up to this point, there was no issue. However, the satellite mock-up separated from Nuriho failed to enter its intended orbit because the third-stage rocket engine shut down 46 seconds earlier than planned for unknown reasons, resulting in insufficient acceleration. Consequently, it re-entered the atmosphere and fell into the sea about 350 km south of Australia. The total flight distance is reported to be approximately 8,100 km. Judging only by the flight trajectory and distance, it is very similar to an ICBM launch rather than a space launch vehicle.

In particular, the fact that the satellite mock-up, which was expected to burn up upon atmospheric re-entry, did not do so has become a basis for suspicion. One of the core technologies of an ICBM is the ability to re-enter the atmosphere after escaping it, which requires advanced materials and design technology to protect the interior from high temperatures without burning, as well as precise attitude and directional control. This is why some speculate that South Korea might have tested actual ICBM atmospheric re-entry technology.

The fact that Nuriho was equipped with a flight termination system also fuels suspicion. There are suspicions that it functions similarly to a 'terminal guidance' system installed on missiles to determine the final target, entry angle, and warhead detonation timing.

Additionally, reports from foreign media have contributed to this. Given that the launch occurred shortly after North Korea's submarine-launched ballistic missile (SLBM) test and amid intensified South-North arms competition, there have been continuous reports suggesting that South Korea might be trying to secure de facto ICBM technology through the Nuriho launch.

The Korean launch vehicle Nuriho (KSLV-II) is soaring powerfully, emitting flames at the 2nd launch pad of Naro Space Center in Goheung-gun on the 21st. Nuriho is a three-stage launch vehicle designed to place a 1.5-ton class practical satellite into low Earth orbit (600?800 km), and 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

▲ KARI: "Completely unfounded"

However, KARI strongly denies the 'ICBM test theory.' They explain that the reason the Nuriho satellite mock-up did not burn up is the same as the reason for the failure to enter the final satellite orbit. Due to the early shutdown of the third-stage rocket engine, Nuriho did not reach the required speed of 7.5 km/s for orbital insertion. As a result, the separated satellite mock-up also failed to gain sufficient acceleration to enter orbit and re-entered the atmosphere at a relatively low speed, leaving debris without burning up completely. A KARI official stated, "The most important technology for ICBMs is to prevent the warhead and re-entry vehicle from melting during re-entry. We do not possess such technology at all. The reason the satellite mock-up did not burn up and fell into the sea south of Australia is because its falling speed was relatively slow."

They also refuted claims regarding the flight termination system, stating it serves a completely different function from missile terminal guidance technology. If Nuriho were to crash or explode mid-air due to a launch failure, significant damage could occur. The system is simply a device to reduce risk by shutting down the engine and cutting the propellant tanks to release highly explosive fuel and oxidizer in case of an emergency.

The launch timing was determined after over a decade of rocket development and has no relation to North Korea's recent SLBM launch or the South-North arms race. KARI explains that because Nuriho uses liquid engines, it requires exposure for fuel injection hours before launch, making it unsuitable for weapons like ICBMs, and it was developed purely as a space launch vehicle.

ICBMs and space launch vehicles are similar yet significantly different. Rocket engine technology for atmospheric escape is common to both. However, they differ greatly in fuel types such as solid or liquid, and in their objectives and required technologies, such as warhead atmospheric re-entry versus satellite orbital insertion. In South Korea, the Ministry of National Defense has announced plans to develop a rocket capable of atmospheric escape using solid fuel by 2030.