South Korea will develop Chollian 6, a next-generation geostationary satellite designed to monitor everything from air-quality changes caused by ultrafine dust, ozone and wildfires to marine disasters such as red tides and oil spills, all with sharper precision from space. The satellite succeeds Chollian 2B, the world's first geostationary environmental and ocean satellite, launched in 2020. The government will also pursue independence in core satellite technology by building geostationary observation sensors domestically for the first time.
The Korea AeroSpace Administration said on the 25th that the geostationary environmental and ocean satellite (Chollian 6) development project, jointly planned with the Ministry of Climate, Energy and Environment and the Ministry of Oceans and Fisheries, had passed a preliminary feasibility study for national research and development projects. The total project cost is about 769.4 billion won ($556 million), with development to run for seven years from 2027 and a launch targeted for 2033.
Chollian 6 will significantly expand the observation range and precision of the currently operating Chollian 2B. The spatial resolution of its environmental sensor will improve from 7 by 8 km to 4.5 by 5 km. As a result, the satellite aims to monitor air pollutants such as ozone, aerosols and nitrogen dioxide across East Asia at roughly the level of individual neighborhoods. A visible-light observation channel will also be added to more precisely distinguish ozone and aerosols at an altitude of about 2 km near the surface, and to produce new data such as nighttime light levels and solar-induced chlorophyll fluorescence (SIF).
Ocean observation capabilities will also be strengthened. The number of observation channels on the ocean sensor will increase from 12 to 16, with five additional channels for polarization observation. The signal-to-noise ratio will rise about 30%, from 788 to 1,030. This will allow more detailed identification of the harmful algae that cause red tides, and precise tracking of marine environmental changes such as sea fog, low-salinity water and oil spills.
Observation efficiency will also improve. On Chollian 2B, the environmental and ocean sensors take turns observing in 30-minute intervals, but on Chollian 6 the two sensors will operate simultaneously. Each observation period will also extend from 30 minutes to up to 60 minutes. That means more observation data can be secured when air pollution or marine disasters occur.
The core goal of the project is technological independence. The environmental and ocean observation sensors will be developed domestically, and the satellite system and body will be developed under the leadership of domestic industry. A hybrid propulsion system combining chemical and electric propulsion will also be developed and applied, replacing the existing chemical propulsion system. The government plans to use the related technology in future deep-space exploration satellites and to help domestic companies enter overseas markets for geostationary satellites.
Once Chollian 6 is launched, Korea's geostationary environmental satellite monitoring network will continue over the long term. If satellites from South America, Australia and Africa are later added to the Northern Hemisphere environmental satellite cooperation system — made up of Korea's Chollian 2B and 6, the U.S. TEMPO and Europe's Sentinel-4 — officials expect a system capable of constantly monitoring air pollutants across the entire globe.
