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[Exclusive] Aerospace & Defense

Korea closer to independent satellite technology

Domestic companies such as LIG Nex1 develop radar signal control system for the multi-purpose satellite Arirang 6

By Nov 22, 2021 (Gmt+09:00)

Korea Aerospace Research Institute (KARI) researchers conduct electromagnetic environmental tests for the Arirang 6 (Courtesy of  KARI)
Korea Aerospace Research Institute (KARI) researchers conduct electromagnetic environmental tests for the Arirang 6 (Courtesy of  KARI)
South Korea has developed its own signal control system for a radar reconnaissance satellite to be launched next year, the system being a key technology of the payload it has until now been relying on other nations for.

The achievement came about a month after South Korea launched its first domestically designed and developed space rocket Nuri, indicating the country is accelerating toward independent space technology.


South Korean companies including LIG Nex1 Co. have developed their own synthetic-aperture radar (SAR) signal control system for the multi-purpose satellite Arirang 6 that an Angara rocket is scheduled to carry from Plesetsk Cosmodrome, about 800 kilometers north of Moscow, Russia around the end of 2022, according to aerospace industry sources on Nov. 21.

The Arirang 6 observes the Korean Peninsula twice a day and sends images from 505 km above sun-synchronous orbit, which is optimal for reconnaissance missions. The satellite is evaluated as world-class since it is able to clearly identify objects from as small as 50 centimeters in width and length, much better than the Arirang 5 that can recognize objects from 1 meter. In order to increase the resolution, the radiated signal bandwidth must be raised.

The Korea Aerospace Research Institute led the project while LIG Nex1 and Asia Pacific Satellite Inc. developed its payload. Korea Aerospace Industries Ltd. (KAI), Hanwha, Doowon Heavy Industrial Co. joined the production of the satellite’s body. Hanwha developed its propulsion system and Doowon was in charge of thermal control components.

The Arirang 6 is currently undergoing electromagnetic environmental tests after completing the total assembly of the flight model (FM).

“We had been relying on foreign technologies since we tried to launch as many satellites as possible,” said a source at the Satellite Technology Research Center within Korea Advanced Institute of Science and Technology (KAIST). “The localization of Arirang 6’s controller will be an important milestone in satellite development.”


A SAR satellite creates an image by synthesizing signal data reflected after shooting electromagnetic waves at ground targets. The satellite operates on the same technical principles as the active electronically scanned array (AESA) radar mounted on cutting-edge fighter jets such as the KF-21. The AESA needs thousands of advanced modules that have radio transmission and reception functions. It is a state-of-the-art radar without the usual rotating plates. The same goes for the SAR satellite. But the satellite is designed for filming while the AESA is specialized in tracking.

The satellite is able to observe and reconnoiter regardless of weather and time. It is much more difficult to develop it than an optical satellite that depends on weather conditions to perform missions.

Control systems, antennas and radio transmission and reception devices are key components of the SAR satellite’s payload. South Korea had been relying on foreign countries for all of the parts.

The SAR control systems consist of a control computer, a digital transmitter/receiver and a waveform generator. When receiving a “tracking” command from a ground base station, the satellite’s antennae receive the signal to create a waveform. The satellite converts it into a SAR signal and shoots it to the target point. The control system needs a field-programmable logic array, a semiconductor only for a satellite. It is a high-level technology to connect the semiconductor to antennae and transmission/reception modules.

It took five years to connect more than 1,500 junctions one by one and check their performance. After preparing the system, it has undergone more than 500 tests repeatedly, including checks on high and low temperatures, special environments in the space, as well as shocks and vibrations.

“It took long since we tried unprecedented technologies in the country,” said a LIG Nex1 official who led the development of Arirang 6’s control system.


In December 2022, a next-generation small satellite will be launched on the Nuri rocket at the Naro Space Center in Goheung, 473 km south of Seoul. The satellite is equipped with an X-band SAR of resolution of 5 m. The KAIST led its development, in which Satrec Initiative Co. and other companies participated.

The satellite is a prototype of 40 military SAR satellites that will be launched by 2029. They are the core of the country’s project to launch 100 ultra-small satellites by 2031.

Those SAR satellites are set to establish a new monitoring system on the Korean Peninsula along with 11 small optical satellites, including one in 2024, five in 2026 and another five in 2027.
South Korea's Nuri rocket takes off
South Korea's Nuri rocket takes off

Write to Hae-Sung Lee at

Jongwoo Cheon edited this article.

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