KARI - Korea Aerospace Research institute

As Korea’s first independently developed geostationary satellite, Cheollian 2A was developed to perform faster and more accurate meteorological observation than Cheollian 1 and establish independent geostationary satellite development capability and core technology independence.
Based on the experience of developing Cheollian 1 and Arirang satellites, from design to assembly and testing of the main body, KARI developed its model of mid-size geostationary satellites with a mission lifetime of 10 years and launch mass of 3.5 tons. Cheollian 2A applied precision control technology using a star tracker to provide the high-precision orientation accuracy required by the high-performance imaging payload in the geostationary orbit. Moreover, KARI has succeeded in localizing more than 25 types of satellite hardware such as satellite-mounted computer, payload connection devices, structures, multi-layered thin film insulation, power distributors, and pyro connection units. It has independently developed the flight software operating satellite hardware, transfer orbit operation technology for geostationary orbit movement after satellite launch, ground control system, image processing system, and observation image geometric correction system (INR).
Main body assembly, performance test, and launch preparation, except for the meteorological payload, were all performed with domestic know-how. Currently, only seven countries, including the United States, European Union, Japan, India, China, Russia, and Israel, have geostationary satellite technology.

Cheollian 2A is a faster, more accurate weather observation satellite. Compared to Cheollian 1, its spatial resolution is improved by four times. The observation period is significantly reduced to 10 minutes for the globe and 2 minutes for the Korean Peninsula, allowing 18 times faster observations. While Cheollian 1 was capable of black and white images only, Cheollian 2A can record color images. Moreover, the number of observation channels has more than tripled, and it can observe the same area three times faster.
With the launch of Cheollian 2A, Korea has greatly improved the weather observation and forecast accuracy and capability to monitor and forecast in the Korean Peninsula and Asian region. Cheollian 2A has 16 channels (4 visible, 2 near IR, and 10 IR) compared to 5 channels (1 visible and 4 IR) of Cheollian 1, more than tripling the number of types of serviced weather data from 16 to 52. Cheollian 2A can detect clouds and calculate cloud optical thickness, cloud particle size distribution, and potential precipitation. It can also detect aerosols, yellow sand, volcanic ash, and sulfur dioxide (SO2) and calculate particle size and optical thickness. Moreover, it can derive meteorological outputs such as sea level and surface temperature, snowfall, sea ice, and ocean currents.