Launchers and Propulsion
KSLV-2 (Korea Space Launch Vehicle-2)
South Korea's homegrown rocket KSLV-2, dubbed Nuri (world), successfully put satellites into low Earth orbit for the first time in its second flight on June 21, 2022. A performance test satellite, deployed from the rocket about 14 minutes after liftoff, exchanged its first signals with a ground station associated with South Korea's research center in Antarctica about 42 minutes after liftoff, according to the science and technology ministry. The satellite will deploy four smaller satellites developed by domestic universities in the coming days. 1)
"We have arrived at a monumental moment not just in South Korea's science and technology history but for South Korea's history as well," science minister Lee Jong-ho said in a televised press conference at the Naro Space Center. "This is a milestone we achieved nearly 30 years after the country launched its first sounding rocket in June 1993." The minister said the government will conduct four additional KSLV-2 launches by 2027 as part of efforts to further advance the country's space rocket program.
President Yoon Suk-yeol hailed the success at his office in Seoul, saying, "the road to space from the Republic of Korea has opened."
The kerosene and liquid oxygen-fueled three-stage rocket KSLV-2 lifted off at the planned time of 3 a.m. EST from the Naro Space Center. Live footage showed the 47.2-meter rocket, emblazoned with South Korea's flag, soaring into the air with bright yellow flames shooting out of its engines. The first-stage booster, powered by a cluster of four KRE-075 engines, was separated at 3:02 a.m. EDT as planned (07:02 UTC), according to the ministry. The separation of its payload fairing took place about one minute and forty seconds later, and the second stage booster with a single KRE-075 engine at 3:04 a.m. The third stage with a KRE-007 engine pushed the payload to the intended orbit of 700 km above the Earth and deployed the performance test satellite at 3:14 a.m. at the orbital velocity of 7.5 km/s, according to the ministry.
Launch: The KSLV-2 rocket lifted off from Naro Space Center on the southern coast of South Korea on 21 June 2022 at 4 p.m. (07:00 GMT). A 162.5 kg satellite designed to verify the rocket's performance successfully made contact with a base station in Antarctica after entering orbit, officials said. 2)
Nuri's Payload Overview
This launch was Nuri's second demonstration flight and KARI's fifth orbital launch attempt overall. On this flight, Nuri carried a 1.2 metric ton mass simulator, the 162.5 kg PVSAT (Performance Verification Satellite), four CubeSats, and a dummy CubeSat successfully to orbit. 3)
PVSAT is a test satellite to verify domestically-built satellite hardware as well as Nuri's performance in flight. The satellite is relatively small, at roughly 0.93 x 0.9 x 0.89 meters in size, with a mass of 162.5 kg. Solar cells will be used to power the spacecraft. Equipped on the satellite are five domestically-built components to be tested in the space environment.
First is a 1 kg Electrically-Heated Thermoelectric Generator (ETG) to generate electricity using temperature differences. This technology could be used for lunar exploration and development programs. Another instrument is a 9 kg Control Moment Gyroscope (CMG) to act as an actuator for high-speed attitude control. The CMG will be used to test gyroscope technology for future missions.
A 0.4 kg hemispherical S-band antenna is used as a redundant antenna. This antenna is used to test the performance of an S-band antenna for telemetry/command transmissions. A Video Camera System (VCS) is used on the spacecraft to record the ejection of the CubeSats – which will take place from the spacecraft. The captured data and video is transmitted back to Earth using the S-band antenna.
On the satellite are five CubeSat deployers, four of which hold university-built CubeSats. The largest CubeSat is the 6U STEP Cube Lab-II which has a mass of 9.6 kg. This CubeSat is equipped with an optical mid-infrared/infrared camera as Korea's first electro-optical mid-infrared multi-band Earth observation mission. The second-largest CubeSat is the 3U SNUGLITE-II with a mass of 3.8 kg. This CubeSat will be used as an educational amateur radio satellite with a GPS receiver.
Next is the 3U Multi-spectral Imaging for Monitoring Aerosol by Nanosatellite (MIMAN) with a mass of 3.7 kg. MIMAN will use multispectral imaging to monitor aerosols. Repeater Arrangement & Disaster Early View (RANDEV) is the fourth and final active CubeSat. This 3U/3.2 kg CubeSat will be used to collect images of potential hazards from volcanos, coasts, and clouds.
The final CubeSat on PVSAT was a 3U dummy satellite.
Some background on KARI's program
In the maiden flight last year, KSLV-2 reached its intended altitude, but its third-stage engine shut down 46 seconds early, releasing its 1,500-kilogram dummy payload at less than orbital speed. The dummy payload fell back to Earth south of Australia. The premature engine shutdown was later blamed on improperly anchored helium tanks inside the upper stage. The Korean Aerospace Research Institute (KARI), responsible for the rocket's development, fixed the flaw by reinforcing the structure anchoring the helium tanks.
KSLV-2's second launch was initially set for June 15, with a backup launch window spanning June 16-23. However, it was delayed to the following day due to strong winds. It was delayed again after engineers found a problem with a sensor inside the oxidizer tank of the rocket's first-stage booster during a final pre-launch checkup at the launch pad. KARI said readings on the malfunctioning sensor remained static when the tank was being loaded. To fix the problem, the rocket was pulled off the launch pad and rolled back to the hangar June 15. KARI confirmed that the problem was confined to the sensor and replaced it with a new one. Then it set June 21 as the rocket's launch date.
KSLV-2 — which cost South Korea an estimated 2 trillion won ($1.6 billion) to develop — is the first step for South Korea's ambitious space program, including the launch of the nation's first robotic lunar lander on a domestically developed rocket by 2030.
The country had previously launched a space launch vehicle from Naro Space Center in 2013, a two-stage rocket built mainly with Russian hardware. That launch came after years of delays and consecutive failures. The rocket, KSLV-1, reached the desired altitude during its first test in 2009 but failed to eject a satellite into orbit, and then exploded shortly after takeoff during its second test in 2010.
1) Park Si-soo, "South Korean rocket puts satellites in orbit for the first time in second flight," SpaceNews, 21 June 2022, URL: https://spacenews.com/south-korean-rocket-puts-satellites-in-orbit-for-the-first-time-in-second-flight/
2) "South Korea's second space rocket launch successfully puts satellites in orbit," Reuters, 21 June 2021, URL: https://www.reuters.com/world/asia-pacific/south-korea-prepares-second-space-rocket-attempt-2022-06-21/
3) Lee Kanayama, "KARI reaches orbit on second test flight of domestic Nuri rocket," NASA Spaceflight.com, 21 June 2022, URL: https://www.nasaspaceflight.com/2022/06/nuri-second-test-flight/
The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com).