South Korean Satellite Launch Fails as Third Stage Falters

by Douglas Messier
Managing Editor

The maiden flight of South Korea’s first domestically produced satellite launch vehicle failed on Thursday due to the premature shutdown of the rocket’s third stage, the nation’s space agency said.

The Korea Aerospace Research Institute (KARI) said the Nuri’s rocket’s first and second stages performed nominally after liftoff from the Naro Space Center at 5 p.m. local time. The failure of the booster’s third stage meant it was unable to place a dummy payload into low Earth orbit. Engineers are analyzing data from the flight to determine what caused the premature shutdown.

KARI previously announced plans to conduct a second flight of Nuri on May 19, 2022. The launch date could shift depending upon the findings of the failure investigation. The rocket will carry a dummy satellite weighting 1,300 kg (2,866 lb) and a performance verification satellite weighing 200 kg (441 lb).

Nuri, which is also known as the Korea Satellite Launch Vehicle II (KSLV-II), is designed to give South Korea its own domestic launch capability, and to allow the nation to compete on the international market. Five other Asia-Pacific nations — China, India, Japan, New Zealand and North Korea — have launched satellites into orbit from their own soil.

Nuri rocket on the launch pad at the Naro Space Center. (Credit: KARI)

Nuri is a three-stage, 47.2 meter (155 foot) tall booster capable of placing 1,500 kg (3,307 lb) into a 600-800 km (373-497 mile) high low Earth orbit (LEO) and 2,600 kg (5,732 lb) into a 300 km (186 mile) high orbit. Nuri has a gross weight of 200,000 kg (440,925 lb) and a diameter of 3.5 meters (11.5 feet).

Nuri’s first stage is powered by four KRE-075 engines with a specific impulse of 289.1 seconds. A single KRE-075 vacuum engine powers the second stage, with one KRE-007 engine on the third stage. All six engines were developed by South Korean engineers and use Jet A-1 fuel and liquid oxygen.

 According to the KARI website, 17 KRE-075 engines had been built and tested 146 times with a cumulative combustion time of 14,365 seconds as of February 2020. The single longest KRE-075 burn time was 260 seconds. Nine KRE-007 engines were developed and tested 77 times, with a cumulative combustion time of 12,326 seconds. 

On Nov. 28, 2018, KARI launched the single stage Test Launch Vehicle (TLV) to evaluate the KRE-075 engine in flight. The engine burned for 151 seconds during a 10-minute flight that saw the TLV reach an altitude of 209 km (130 miles). KARI declared the flight test to be a success.

Test Launch Vehicle lifts off from Naro Space Center on Nov. 28, 2018. (Credit: KARI)

KARI designed the rocket with Hanwha Aerospace manufacturing the engines. Korea Aerospace Industries oversees final assembly of the booster. Hyundai Heavy Industries built the launch pad. Development costs are estimated at 1.96 trillion won (US $1.7 billion), which includes spaceport development.

Engineers are working to developed a lighter and more powerful version of the KRE-075 engine that would increase Nuri’s payload from 1,500 kg (3,307 lb) to 2,800 kg (6,173 lb).

Engineers also have plans to develop a Nuri variant capable of launching satellites into geosynchronous orbit. The first stage will be powered by four KRE-090 engines with four side boosters each equipped with a single KRE-90 engine. The second stage will be powered by a KRE-090 engine, and the third stage by a KRE-010 engine.

On Sept. 7, the Ministry of Science and ICT held an online video conference with South Korean aerospace companies to discuss a five-year plan aimed at improving the nation’s launch vehicle technology by transferring responsibility to the private sector. The government plans to spend 687.38 billion won ($587.31 million) on the program.

“The Ministry of Science and ICT can improve the reliability of Korean launch vehicle through the Korean launch vehicle upgrade project (new in 2022, hereinafter referred to as the ‘Advanced Project’), while transferring the Korean launch vehicle development technology to the private sector to raise the industrial launch vehicle development capability,” the ministry said in a press release.

“For the upgrade project, the host company will systematically transfer projectile development technology and know-how from the Korea Aerospace Research Institute [KARI] while jointly carrying out the production and repeated launches of the launch vehicle,” the press release added.

The flight on Thursday was South Korea’s first domestic orbital launch attempt in more than eight years. On Jan. 30, 2013, a Naro-1 rocket placed the STSAT-2C technology demonstration satellite into low Earth orbit.

It was the final of three launches for now retired Naro-1, which was also known as Korean Satellite Launch Vehicle 1. The booster was composed of a Russian Angara first stage with a downgraded engine and a South Korean developed solid-fuel upper stage. Two previous Naro-1 launches failed in 2009 and 2010.