It was October 21, 2021, 5 p.m. when Nuri, the Korean Space Launch Vehicle (KSLV-II), flied up to the sky. The separation of the faring, which did not happen successfully at the launching of Naro, was implemented at the altitude of 191 km. Nuri reached an altitude of 700 km about 15 minutes after the launching. The success was just around the corner, but the third-stage engine failed to operate as it was planned. Since the dummy satellite didn’t reach the orbit, some people said that the project was a ‘half success.’ However, the launching of the launch vehicle with a 1.5 ton satellite, based on Korea’s homegrown technologies, was a tremendous accomplishment. Behind the success was Ko Jeonghwan, Director of the Headquarters of Korean Space Launch Vehicle Development Program at Korea Aerospace Research Institute, who orchestrated the entire launching process. Looking forward to seeing the second launch of Nuri in May, we met Director Ko, who has led the Nuri vehicle development program for 8 years since 2015.

1. We’d like to ask your thoughts about the launching of Nuri in October last year. It must have been a more special experience to you, since you have orchestrated the development of Nuri for 7 years as a director of the program.

It was the seventh year as the Director of the Headquarters of Korean Space Launch Vehicle Development Program, but I have worked on the development of launch vehicles for 20 years at the Korea Aerospace Research Institute (KARI), including the development of Nuri, the previous space launch vehicle. So, the day was like a gradation exam to me. The official launching project began 10 o’clock in the morning, and the due time was pushed behind one hour from 4 p.m. The whole process was like a very long time to me. As the time for launching approached, my mind became so complicated, because my works for the past 20 years were about to be evaluated within just 16 minutes. I wanted it to go smoothly, but I could not be confident about the success. Like our Korean citizens, I was also in suspense while watching the launching.

2. It is often said that the launching success ratio of a newly developed launch vehicle is below 30%. Nuri also left unfinished tasks. What is the significance of the launching of Nuri this time?

Korea began to develop satellite technologies at the end of 1990s. Since then, we have reached a considerably high level. The development of launch vehicle began at the end of 1980s, but it has been very slow until now. When I firstly joined KARI in 2000, my first project was to develop a liquid propellant rocket (KSR-III), one step before the satellite launch vehicle. It was followed by the Naro project, jointly developed with Russia, and then the Nuri project. The state-to-state technology transfer is extremely limited because the space launch vehicle technologies can also be used to develop weapons of mass destruction. At the time of developing Naro, technology transfer was excluded from the beginning. The launching of Naro this time may not be considered as a perfect success but this allowed us to verify the technologies that we have accumulated from the development of the early science rockets and Naro.

Nuri, the space launch vehicle produced by Korea’s own technology, is to be launched for the second time in May. ⓒKARI

3. We are wondering how you could overcome the situation where technology transfer was impossible.

We used to read the Russian books about space written in 1960s, and look into the rocket engines exhibited in the museums of the countries of space power. We did everything we could to get the information. During the development of Naro, we even collected the notes that the Russian engineers left and studied them by using Russian dictionary. At that time, the security agents were always there in the Naro Space Center where they thoroughly monitored us, and so it was difficult even to talk with the Russian engineers. So, when there was something good, after the security agents left the work, we used to invite the Russian engineers in the evening, grill bacon, and drink soju together, developing friendship. After that, when we asked questions, they started to answer. From those experiences, we were able to gather considerable knowledge that was necessary to develop Nuri.

4. What made you continue to develop the space launch vehicle despite the many failures?

A rocket is prepared for about 10 years and launched at once. The launching time is also very short, such that the launching time of Nuri, 16 minutes, was considered as a very long time. However, looking at the rocket rising against the gravity, we forget the hard time in the past and we are thrilled. Think about the joy that you feel when tens of thousands of components operated in a predetermined sequence, and the earthshaking rumble of launching the vehicle. These things make us take the adventures continuously despite the many failures. In addition, we are strongly motivated by the fellow researchers working together in KARI to develop launch vehicles. Their zeal for rocket, industriousness, and the patience for finding solutions by putting head together have driven all of us to continue. That kind of enthusiasm must have encouraged us to continue the development of Nuri.

5. What will be the future of the Korean aerospace program?

The space is still far from the non-experts. However, we will continue to develop various resources through the space observation, and the satellite-based communication technologies will continue to grow. Therefore, the humankind will never stop their adventure to the universe. In advanced countries, private companies are actively participating space development. Korea began the space development late, and we are now forming the environment. If Nuri is successfully launched into the orbit, the space development will be carried out more actively in Korea, and the space will be familiar to all citizens. Moreover, we will be able to carry satellites and other things by means of a launch vehicle, and we will enjoy travel to the space as well.

On January 18, the Falcon 9 rocket developed by the US aerospace company Space X rose up to the space in a parabolic trajectory with 49 Starlink satellites for establishing the space internet. If Nuri is successfully launched, the space development is expected to be promoted in a full scale in Korea as well. ⓒSpaceX 

6. What’s the schedule for launching Nuri?

At the first launch, the target combustion time of the 7-ton third-stage engine was 521 seconds, but it ended at 475 seconds. That’s why the speed was just 6.5 km/sec, which was below the target speed of 7.5 km/sec. That is also why the dummy satellite failed to get into the space orbit. The second launching of Nuri is scheduled in May. We have investigated the causes of the problems that occurred in the first launch, and are preparing the second launch. At the second launch, we will launch a small satellite manufactured by a Korean company to verify its performance. We will continue to launch satellites produced in Korea. Of course, the second launch may also be proved to be a failure. However, we will learn from our failure, and improve our technology not to repeat the same mistake. We ask for you encouragement for us.

7. Please say a word to SNU students.

I ask you whatever things you really like to do, rather than doing things quickly. Like the rockets that are launched after a long time of preparation, even if you feel that you are slightly behind others, choose to do what you like to do. If you plan for yourself, give meanings to it, and achieve something valuable, that will be an amazing experience. If you take challenges again based on the experience, the outcome will be a better one. I encourage you to find what is meaningful to you and steadily go for it.