Space Launch Vehicle Development in. = Korea Aerospace Research Institute

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1 SpaceOps Conferences May 2016, Daejeon, Korea SpaceOps 2016 Conference AIAA Space Launch Vehicle Development in Korea Aerospace Research Institute Jeonghwan Ko 1 and Sang Yeon Cho 2 Korea Aerospace Research Institute, Deajeon, Korea AC CDR INS INGU KARI KhSC KM KSLV KSR LEO LOX PLF Since its establishment in 1989, Korea Aerospace Research Institute(KARI) has been developing rockets for more than 25 years for purely scientific and civilian purposes. Herein, we present the historical review of rocket development in KARI and also current and future activities in KARI for the development of space launch vehicles. In the beginning, KARI developed solid propellant sounding rockets named KSR(Korea Sounding Rocket)-I and KSR-II for scientific atmospheric measurements. After that, KARI developed a liquid propellant sounding rocket, KSR-III, and successfully finished flight test in The KSR- III rocket utilized pressure fed kerosene and liquid oxygen as propellants, and was equipped with an indigenous engine of 13 ton thrust developed in Korea. After developing a series of sounding rockets, KARI started KSLV(Korea Space Launch Vehicle)-I program in 2002 to develop space launch vehicle to be launched from Korean territory. KSLV-I was developed via international collaboration with Russian partners. The first stage of KSLV-I was developed by the Russian partners and was based on liquid engine using kerosene and liquid oxygen. The 2 nd stage was developed by KARI based on domestic technology and was based on solid rocket engine. The space center for the launch of KSLV-I was built in the southern province of Korean peninsula. KSLV-I was designed to put 100kg satellite into 300kmx1500km orbit. The KSLV-I had 3 test flights with 2 failures in 2009 and 2010, and 1 success in In order to have a capability to launch a 1.5ton class satellite into 700km altitude sun synchronous orbit, KARI began KSLV-II program in The KSLV-II launch vehicle is 3 staged and is based on 75ton class engine for the 1 st and the 2 nd stages, and 7ton class engine for the 3 rd stage. Both 75ton class and 7ton class engines are currently under development in Korea. Both engines are based on turbopump for the pressurization of propellants, and utilize gas generator for the operation of turbopumps. The initial flight test of KSLV-II full size vehicle is scheduled in the year The KSLV-II vehicle will be employed for the launch of some of the satellites built through the government programs in the future and also for the launch of the lunar exploration spacecraft which is scheduled to be developed by KARI. Once the KSLV-II launch vehicle is successfully developed, KARI has a plan to develop a vehicle which can launch geosynchronous orbit satellites in the future. Abbreviation = assembly complex = critical design review = inertial navigation system = inertial navigation and guidance unit = Korea Aerospace Research Institute = Khrunichev Space Research and Production Center = kick motor = Korea Space Launch Vehicle = Korea Sounding Rocket = low earth orbit = liquid oxygen = payload fairing 1 Executive Director, KSLV-II R&D Head Office, jko@kari.re.kr. 2 Head of Team, Launcher Assurance Team, KSLV-II R&D Head Office, chosangy@kari.re.kr 1 Copyright 2016 by Jeonghwan Ko. Published by the, Inc., with permission.

2 RCS SSO TLV TVC = reaction control system = sun synchronous orbit = test launch vehicle = thrust vector control I. Introduction HE history of non-military launch vehicle development in Korea is not as long as that of other countries which T have their own space programs. However, since the beginning of its history in 1989, Korea Aerospace Research Institute (KARI) has been actively developing rockets purely for scientific or civilian purposes, and is currently developing a space launch vehicle which is capable of launching a 1.5 ton payload into 700km SSO. KARI was established in 1989 by the Korean government for the national technical development in the area of aerospace related science and engineering including developing aircrafts, satellites, and rockets, etc. KARI started its rocket development from the year of 1990 by developing a series of sounding rocket programs KSR-I, II and III for purely scientific missions such as various high altitude atmospheric data acquisition. Based on this experience, Korea's first space launch vehicle, Korea Space Launch Vehicle (KSLV)-I, a.k.a Naro, was developed and was launched into orbit in KARI now is developing KSLV-II based on the experience acquired during KSR series and KSLV-I program. KSLV-II will launch 1.5 ton-class satellites in low earth orbit and, after that, it will be used as a launcher for other space programs such as the lunar exploration. 1 In this paper, the historical review of rocket development in KARI and also current and future activities in KARI for the development of space launch vehicles are presented. Review on the development of sounding rockets is presented in Section II, while the development of KSLV-I and KSLV-II are presented in Sections III and IV, respectively. Future plans and conclusions are given in Sections V and VI. II. The Development of Sounding Rockets (KSR series) Korea Sounding Rockets (KSRs) were the series of rockets which KARI had developed as the first step of the space launch vehicle development program. They had some scientific missions and were continued from KSR-I, which had solid motor as a propulsion system, to KSR-III which had a liquid propellant engine. The development of KSR series took over a decade and after the programs, KARI could acquire several key technologies for space launch vehicle such as inertial navigation, thrust vector control and stage separation etc. 2 A. KSR-I KSR-I was the country s first scientific rocket, whose development had begun in 1990 and was launched twice in It was a single staged solid rocket, whose length was 6.7 m, and diameter was 0.42 m, and had no guidance system. KSR-I s mission was to observe the atmospheric layer and the ozone layer at an altitude of 35 ~ 75 km above the Korean Peninsula, with a payload (UV radiometer) of less than 200 kg. Through the development of KSR-I, KARI s design capability of solid propellant rocket could be verified. 3 B. KSR-II Figure 2. Launch of KSR II KSR-II was a scientific rocket developed from 1993 to 1998 and launched twice in 1997 and in It was middle-sized 2 stage solid propellant rocket, which was 11.4 m long and 0.42 m in diameter. The propulsion system of the KSR-I was used for the 2 nd stage propulsion system of KSR-II. With a payload of around 150 kg of scientific equipment, it 2 Figure 1. Korea Sounding Rocket (KSR) - I conducted various research tasks, including measurement of the ion layer environment and ozone layer distribution at an altitude of around 140 km above the Korean Peninsula. KSR-II reached a maximum altitude of km and observed space x-rays for the first time in Korea. Through the development of

3 KSR-II, KARI could verify the technologies for payload fairing (PLF), attitude control system, inertial navigation system (INS), and stage separation system. C. KSR-III KSR-III was the first non-military liquid propellant rocket in Korea, which had been developed from 1997 to 2003 by KARI. In addition to the vehicle, liquid propellant engine had been developed during the same period. The propellant and oxidizer used in KSR-III were kerosene and liquid oxygen (LOX), and the pressurized propellant feeding system was adopted to supply propellants to the engine whose thrust was 13 ton. Figure 3. KSR-III engine test Figure 4. Launch of KSR III At the early stage of engine development, KARI had suffered from the combustion instability problem, which was later solved successfully after using baffles. 4 KSR-III was launched on November 28, KSR-III rocket was 14 m long with 1 m diameter and the total weight at liftoff was about 6 ton. Its flight time was 231 second and the flight distance was 80 km. KSR-III had observed the ozone concentrations and earth magnetic field during flight. From the result of KSR-III development, the basic space launch vehicle technologies such as liquid propellant feeding, cryogenic ground support, thrust vector control (TVC), pressurized tank using composite material and rocket launch operation have been obtained, and technology of avionics systems including INS has been verified. 5 III. KSLV-I, Naro, Country s the 1 st Satellite Launcher KSLV-I, Naro, was the 1 st Korean satellite launch vehicle, whose mission was to inject 100 kg satellite into a low earth orbit (LEO). KSLV-I was part of a space program to acquire sufficient technology and experience to be able to independently develop a space launch vehicle in accordance with the Mid-to-Long Term National Space Development Plan of Korean government. 6 The development of KSLV-I was through the international cooperation with the Russian partners. Following the agreement between two countries in 2004, KSLV-I was jointly developed by KARI and the Russian partner Khrunichev Space Research and Production Center (KhSC), which has a long history of developing space launch vehicles and international space station. 7 KSLV-I was two-staged space launch vehicle with the length of 33.5 m. The 1 st stage was developed by KhSC with the propellant tanks and liquid propellant rocket engine, etc. The vacuum thrust for the 1 st stage engine was about 210 ton, using kerosene and LOX as fuel and oxidizer. The length of the 1 st stage is 25.8 m and maximum diameter is 2.9 m. Upper stage is made up of the 2 nd stage propulsion system, onboard electrical systems, payload fairing, and spacecraft, etc. The length of upper stage is 7.7 m. The 2 nd stage propulsion system is Kick Motor (KM) using solid propellant, which is developed by KARI. It has variable nozzle with thrust vector controller and the vacuum thrust of KM is almost 9.9 ton. 3

4 Figure 5. KSLV-I KM combustion test Figure 6. KSLV-I System integration The 1 st stage had been delivered from Russia by air, and the whole vehicle system was integrated inside the assembly complex (AC) in Naro Space Center which is located in far south of the Korean Peninsula. The 1 st launch of KSLV-I was performed on August 25, 2009, and unfortunately it was not successful. At 215 second after the launch, on the event of the separation of PLF, one of the fairing halves didn t separate from the vehicle. As a result, the 2 nd stage could not maintain its proper course and attitude, and the mission went to failure. The 2 nd launch, which was executed on June 10, 2010, was also failed due to the explosion in the interstagecompartment at around 137 seconds after lift-off. After many discussions and studies to apply proper measures, KARI and KhSC tried the 3 rd launch on January 30, Finally, the mission of KSLV-I was successful, and the Korea became the 11 th nation in the world who have sent the satellite in earth orbit using their own launch vehicle. After the KSLV-I program, KARI have learned and verified many technologies not only for launch vehicle but also launch complex and launch operation. In addition, over 150 companies have been involved in the program, and helped to advance industrial background to develop indigenous launch vehicle in Korea. KSLV-I program was considered as one of the top ten scientific and engineering achievements since the independence of the Republic of Korea. Figure 7. Launch of KSLV-I, Naro 4

5 IV. Korea Space Launch Vehicle-II (KSLV-II) After finishing KSLV-I program, KARI took the next step to develop new satellite launch vehicle named KSLV- II. 8 KSLV-II program is an ambitious project of KARI with the budget over 1.6 billion USD and the duration over ten years. Main goal of KSLV-II is to develop an indigenous space launch vehicle capable of putting a 1.5 ton multipurpose satellite into low earth orbit of 600~800km altitude. The development of KSLV-II consists of 3 phases. The period of phase 1 was from March 2010 to July During the phase 1, system design and preliminary design has been performed, and construction of the several test facilities for engine subsystems and engine system test has been completed. In addition, 7-ton-class liquid engine system test has been successfully initiated during this period. Figure 8. Goals of development phases of KSLV-II; TLV and 3 staged launch vehicle The period of the phase 2, which is now underway, is from August 2015 to March Main tasks of the phase 2 include critical design of launch vehicle, ground test of 75-ton-class engine system, and the launch of Test Launch Vehicle (TLV) to verify 75-ton-class engine system through an actual flight. The final phase 3 of KSLV-II will last until March 2021, and it includes two launches of 3 staged launch vehicle. A. Vehicle KSLV-II is 47.2m long with the maximum diameter of 3.5m. Figure 9 shows the comparison between KSLV-I and KSLV-II. The maximum payload capacity of KSLV-II is 1500kg for 700 km sun synchronous orbit (SSO) and 2600 kg for 300 km low earth orbit (LEO). The vacuum thrust of the 1 st stage is 300 ton, consisting of 4 clustered 75-ton-class liquid rocket engines. For the 2 nd stage, a 75-ton-class liquid rocket engine with expanded nozzle will be installed and for the 3rd stage, a 7-ton-class liquid rocket engine will be used. Each engines will be illustrated more minutely in following chapter. After several design cycles, the design baseline of the vehicle has been set up during preliminary design period, and the critical design review (CDR) is planned in The 1 st stage consists of propulsion system including propellant tanks and feeding system, retro motors, fire prevention system for engine compartment, 1 st stage avionics systems and engine actuator for TVC, etc. The total mass of the 1 st stage is 143 ton, vacuum thrust is about 300 ton, vacuum specific impulse is sec, and engine operating time is 126 sec. In the 2 nd stage, retro motors, ullage motors, TVC system, roll control system, and transfer module between stages are included as well as the 5 Figure 9. Comparison of KSLV-I and KSLV-II

6 propulsion system. The total mass of the 2 nd stage is 42.3 ton, vacuum thrust is 80 ton, vacuum specific impulse is sec, and engine operating time is 144 sec. The 3 rd stage consists of propulsion system, 3 rd stage avionics system such as inertial navigation and guidance unit (INGU), TVC system, satellite adapter, reaction control system (RCS), etc. The total mass of the 3 rd stage is 12.6 ton, vacuum thrust is 7 ton, vacuum specific impulse is sec, and engine operating time is about 500 sec. PLF is 7 m long whose weight is 700 kg, and consists of fairing structure, separation system, acoustic blankets and thermal control system, etc. To confirm flight readiness of the newly developed 75-ton-class engine system, KARI has a plan to launch test vehicle (TLV), which is similar to a configuration in which only the 2 nd stage and the 3 rd stage of KSLV-II are combined. The length of the TLV is 26.1 m and the diameter is 2.6 m. Engines used in the 1 st stage of the TLV is same as that of the 2 nd stage of KSLV-II except nozzle size. Avionics systems of TLV are nearly same as those of KSLV-II, but some subsystems in KSLV-II 3 rd stage will be replaced with dummies. B. Engines KARI has been developing 2 kinds of liquid rocket engines for KSLV-II; one is 75-ton-class engine system and the other is 7-ton-class engine system. 75-ton-class engine will be installed in the 2 nd stage and also will be clustered to make the 1 st stage propulsion system of KSLV-II. 7-ton-class engine will be employed in the 3 rd stage. Each engines uses kerosene and LOX as fuel and oxidizer. They are gas generator turbopump open cycle engines with regeneratively cooled nozzles. The components of an engine such as combustion chamber, gas generator, turbo pump, and main valves have been developed by KARI from the beginning of the program and are integrated to make an engine system. Up until now, 7-ton-class engine system test are successfully ongoing, and 75-ton-class engine system test will be started in the early half of Figure ton-class and 7-ton-class engine systems Figure 11. Load analysis for 75-tonclass engine Figure 12. Firing test of 7-ton-class engine system 6

7 C. Test Facilities To verify the performance of engine systems, KARI has built several test facilities in Naro Space Center. They are as follows; Combustion Chamber Test Facility, Turbo-pump Test Facility, Rocket Engine Test Facility, High Altitude Engine Test Facility. Figure 13. Propulsion Test Facilities; (from upper left, clockwise) 3rd stage engine Test Facility, Combustion Chamber Test Facility, Rocket Engine Test Facility, High Altitude Engine Test Faciltiy These facilities enabled the large-scale/high-thrust engine tests which were previously impossible in Korea. In these test facilities, component tests for combustion chambers, turbo-pumps and gas generators for 7-ton-class and 75-ton-class engines are being performed, 7-ton-class engine system test in ground condition also is ongoing, and 75-ton-class engine system tests in ground and high altitude conditions will be started soon. In addition, Propulsion System Test Complex is under construction, and integrated firing test and qualification test of TLV will be performed in V. Future Space Launch Vehicle of KARI KARI s future progress direction of launch vehicle is an independent development of reliable and economically viable launch vehicle. According to the Mid-to-Long Term National Space Development Plan of Korean government, after the development of KSLV-II, it will be used as launchers for lunar exploration missions and practical class satellite missions. 9 Furthermore, for the next step of KSLV-II, KARI has a vision to build a launch vehicle which can inject a 3-ton-class satellite into middle earth orbit or geo-stationary orbit. Apart from all these technical developments, however, KARI has an important task to economize the production cost and to increase the reliability of a launcher, which is crucial for the commercialization of launch vehicle service, through the performance improvement and continuous launches of KSLV series. 7

8 VI. Conclusion In this paper, a brief history of launch vehicle development by KARI is presented. As explained in the manuscript, through the development of KSR series and KSLV-I, KARI has established technical foundation to build a launch vehicle for practical class satellites. Currently, the second phase development of KSLV-II program is ongoing, and KARI plans to launch KSLV-II in Naro space center in near future. In accordance with the national space development plan, the result of KSLV-II development will be served as a foundation for the next launch vehicle programs of Korea. KARI has a long-term goal to develop next generation launch vehicles which can be employed for future space activities in Korea. References 1 KARI, Proposal of Korean Mid- and Long-term Space Development Plan Modification (MOST, 2000) 2 KARI homepage, URL: [cited 21 March 2015]. 3 An, H. J., Seeking Independence in Space: South Korea s Space Program ( ), Quest, No.2 Vol. 20, Bethesda, MD, 2013, pp Seol, W. S, et al, High Frequency Combustion Instability Experienced during KSR-3 LRE Development, SNU conference, Chae, Y. S., et al, Development of a liquid Propellant Rocket, Korea Sounding Rocket (KSR)-III, the 5 th international symposium on liquid space propulsion, Chattanooga, Tennessee, USA, KARI, Naroho White Paper, Lee, C. B, et al, The System Integration and Operation Concept based on the KSLV-I International Joint-Development, Aerospace Technology, No. 1, Vol. 2, KARI, Final report of the 1 st phase of KSLV-II, Song, E. J., et al, Mission Design for a Lunar Orbiter Launched by KSLV-II, Spring symposium of KSAS,