Sejong 4, 5

Sejong 4 [Hancom]

Sejong-4 is a small Earth-observation satellite developed and integrated by Hancom InSpace of South Korea. The 6U CubeSat-class spacecraft is built with domestically produced hardware and self-developed software. It is designed to acquire multispectral imagery and to verify internal satellite system integration technologies.

Sejong-4’s mission focuses on demonstrating satellite system integration capabilities using self-developed real-time operating and flight software. The satellite conducts first-space verification of these systems, including the ability to manage onboard operations and maintain stability in the radiation- and temperature-intensive environment of low Earth orbit.v

A second mission objective is the provision of 5-meter-resolution multispectral imagery. The data support agricultural and forestry monitoring by delivering imagery specialized for vegetation analysis. The satellite also contributes to broader applications such as land-use change tracking, disaster response, and environmental monitoring when integrated into Hancom InSpace’s data-analysis workflows.

Hancom InSpace, an AI-focused data-analysis company within the Hancom Group, developed the spacecraft. The company applied its own NEOS real-time operating system and flight software to operate the onboard computer and manage mission functions. The satellite incorporates domestically produced hardware, including solar panels and structural components. The mission is part of Hancom InSpace’s effort to internalize end-to-end satellite development, from system design to operation.

Sejong-4 is a 6U satellite with a mass of about 7.6 kg. It operates in a 600-km low Earth orbit, circling the Earth every 90 minutes, completing 14–16 orbits per day. Its payload provides 5-meter multispectral imaging capability. The spacecraft is designed to interface with the company’s InStation platform, which integrates heterogeneous data streams using multi-INT and automated AI-driven processing pipelines.

The satellite supports Hancom InSpace’s expanding constellation plans. The company previously launched the Spire Global built and operated Sejong-1 in May 2022 and Sejong-2 in June 2025. Sejong-4 increases the planned data-collection capacity and serves as an intermediate step toward a broader operational constellation.

Sejong 5 is similar and is planned for a launch in mid 2026.