▲ The Naro-1 flying in the air. Provided by i09.com
“Naro-1 launched successfully” was the headline for most Korean media on January 30 when Naro-1, or officially the Korea Space Launch Vehicle (KSLV-1), launched successfully and delivered the payload satellite STSAT-2C to its designated orbit. While this success is a huge achievement for Korea, it still has a long way to go to refine future rockets for more diverse uses.
The Korea Aerospace Research Institute (KARI), the governmental department that designed and created Naro-1, declared on January 31 that STSAT-2C has transmitted two signals to its ground control and thus proved itself to be fully functional. This successful launch made Korea the 11th country to join the “Space Club,” a group of nations that have the ability to create and launch rockets on their own land. Behind all the glory and congratulations on the success of the third launch, there were many flaws in the first and second launches.
First Two Launches
The first launch was set on August 25, 2009. As planned, the rocket lifted off, and the icy-white-colored Naro- 1 disappeared in the blue skies. Korean media outlets immediately hailed the launch as a success, but officials grimly declared that the flight suffered a failure a few hours later.
The first stage of the rocket, provided by one Moscow-based aerospace institution named Khrunichev, functioned without any anomalies. However, the payload fairing separation system malfunctioned 215 seconds after launch and therefore the near fairing of the satellite protective cover stayed bolted to the second stage while the far fairing separated correctly. The added weight on the second stage, after separation from the first stage at the 232 second mark, made the rocket extremely imbalanced and tumble upwards. As a result, the second stage of the rocket was soaring 20km above its designated orbit, along with its payload STSAC-2A that later reentered the atmosphere and disintegrated in the air.
The second launch, performed on June 10, 2010, was a bigger debacle than the first launch. The contact between ground control and the rocket was lost 137 seconds after the launch. According to KARI officials, it is believed that the Naro-1 exploded in midair without definite reason confirmed by both Khrunichev and KARI.
13 engineering experts from Korea and 13 from the Russian Federation formed a Failure Review Board in August, 2010 in order to investigate the reason of the failure. Without surprise, Korea and Russia pointed fingers at each other. While Korea asserted that some significant error occurred in the first stage that Russia built, Russia argues that the error that created this catastrophe was the malfunction of the Flight Terminating System (FTS) of the second stage of the rocket devised by Korea.
▲ The Naro-1 flying in the air. Provided by nytimes.com
The watershed that led to the success of the third launch is the change from a high voltage system to a low voltage system inside the fairing system. During the first and the second launch, Naro-1’s ignition of the fairing system applied a high voltage power supply, which is believed to be the main cause of the malfunction of the ignition.
Then, why did the supply not do the trick? It discharged the electricity of its own battery. At the precise moment when the ignition system was triggered, the inner part of the system is not completely vacuous but it is in a “low vacuous” state. Because of the nature of electricity, high voltage electricity is more likely to be discharged within that state. Eventually, only one of the two fairing system was separated from Naro-1, instead of the designated two.
The low voltage power supply, on the other hand, has less risk of causing similar issues. Although the low voltage supply has its own disadvantages, such as its vulnerability to physical collision, it has proven to be a much better solution than the high voltage supply after hundreds of experiments. The KARI tested whether the new circuit functions properly in a vacuous environment, a low vacuous environment and even with severe outer collision. And the result? Korea launched its first rocket in late January.
The Inevitable Comparison
▲ The Naro-1 and the Unha-3.Provided by yonhapnews.co.kr
Since their foundation, South Korea and the Democratic People’s Republic of Korea (DPRK), otherwise known as North Korea, have been compared from many perspectives. Therefore, at some point the comparison between the third generation of Naro-1 and Unha-3 seems necessary.
The general public might acknowledge the fact that while Naro-1 is not criticized by any nation excluding Korea’s neighbor and political rival, the DPRK, Unha-3 was harshly condemned by many international organizations especially the United Nations (UN) Security Council. However, many do not know the precise reason.
The biggest reason is that the structure of Naro-1 is that of a traditional carrier rocket, used to carry satellites, whereas the structure of Unha-3 is that of an Intercontinental Ballistic Missile (ICBM). Although the DPRK claims through its media that Unha-3 is a carrier rocket and Unha-3 did carry a payload satellite called Kwangmyongsong-3, there is clear evidence that goes against these claims.
Most of the ICBMs have a structure for three distinct stages, in order to make a trajectory similar to a wide and long ellipse, with the warheads on the top of the missile. Unha-3 has the exact same three-stage structure, with the difference being that its payload is a satellite, which is believed by many specialist to be a machine that is not meant to function in the first place. Naro-1, on the other hand, has a two stage structure, and a lower orbit, which cannot be seen on an aggressive launch vehicle.
Not to mention the fact that the fuel and oxidizer, the fuel that is used to ignite the thrusters of Unha-3 is also similar to that of ICBMs. The fuel of Unha-3 is hydrazine and the oxidizer is nitric acid, which is not applied to rockets except China, where they transformed their ICBMs into carrier rockets. The uniqueness of the fuels is that they are capable of remaining in their state at room temperature, which means that Unha-3 could be launched in a very short amount of time as soon as DPRK officials want it to be in the air. Naro-1, on the other hand, uses liquid oxygen as its fuel, which has to be kept under extremely low temperature and high pressure, which means it takes relatively more time to prepare to launch.
▲ The KARI scientists working.Provided by science.dongascience.com
Clearly, Naro-1 is just the first step of the development of Korea’s aerospace industry. The next goal for KARI and the Korean government is to launch a carrier rocket that is developed by Korea alone and carry a 1.5-ton payload satellite into Earth’s lower orbit (600~800km above sea level) in 2018. However, this goal seems a bit “ambitious” since in order to do that Korea has to develop the first stage of the rocket, the most crucial part among all, by itself. Not to mention the fact that even though the Russian aerospace institution provided the first stage of Naro-1, it took Korea five years to successfully launch Naro-1 on its third try.
The Korean government is taking every means to achieve that goal. It is financing a huge amount of money into the industry even though there is a big group of Korean citizens who do not like their government doing so. Nonetheless, the Korean government also needs to consider a more fundamental solution. That solution would be to finance education in the field of aerospace technology. According to the 2012 ranking of the university ranking company QS, there are only three universities in the top 100 list of global universities in aerospace courses. Evidently, in case of a long-term solution, this is where the Korean government has to pay attention.