South launches 4th recon satellite to monitor North's military movement

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South launches 4th recon satellite to monitor North's military movement

Published: 22 Apr. 2025, 14:25 Updated: 22 Apr. 2025, 19:37

Audio report: written by reporters, read by AI

A Falcon 9 rocket carrying the fourth satellite, Unit 4, under the 425 Project, takes off from Cape Canaveral Space Force Station in Florida on April 22. [YONHAP]

The South Korean military successfully launched its fourth independent reconnaissance satellite on Tuesday, bringing the country closer to completing the 425 Project aimed at building satellite-based surveillance capabilities for monitoring North Korea’s nuclear and missile activities.

With only one satellite — Unit 5 — remaining, the independently operated satellites are expected to become a core asset for the Kill Chain, South Korea’s pre-emptive strike system against signs of imminent North Korean attacks.

The fourth satellite under the 425 Project was successfully launched at 9:48 a.m. on Tuesday from Cape Canaveral Space Force Station in Florida, according to the Ministry of National Defense.

Unit 4 is equipped with a high-resolution Synthetic Aperture Radar (SAR) and, like Units 1 through 3, was launched aboard a Falcon 9 rocket developed by SpaceX, the aerospace company founded by Tesla CEO Elon Musk.

“Unit 4 separated from the launch vehicle around 10:03 a.m. in Korea and successfully entered its target orbit,” the Defense Ministry said. The satellite was scheduled to attempt its first communication with the ground station roughly three hours after launch, which will determine the final success of the mission.

The satellite will undergo an initial Launch and Early Orbit Phase operation for about two weeks, which includes deploying its solar panels and antenna reflector, verifying platform functions and confirming normal operation of the satellite. Full operational deployment is expected in about six months, according to military officials.

The 425 Project, launched in December 2017, is Seoul's initiative to secure mid- to large-sized reconnaissance satellites. It involves launching a total of five satellites: one electro-optical (EO) infrared (IR) satellite in Unit 1, and four SAR satellites in Units 2 through 5. The project name “425” is derived from the English acronyms SAR and EO, which it phonetically resembles.

A Falcon 9 rocket carrying the fourth satellite, Unit 4, under the 425 Project, takes off from Cape Canaveral Space Force Station in Florida on April 22. [YONHAP]

“This project is expected to greatly enhance our military’s independent capabilities to detect signs of North Korea’s nuclear and missile provocations and to monitor strategic targets deep inside enemy territory,” a military official said.

“Strategic targets” include North Korean leader Kim Jong-un and the North’s leadership. The more satellites South Korea has, the more it will be able to monitor Kim’s movements in real time. Until now, South Korea has largely relied on U.S. intelligence for such surveillance.

The differing types of satellites in the 425 Project were deliberately chosen to complement each other’s weaknesses and maximize their strengths.

“Units 1, 2 and 3 form South Korea’s first satellite constellation and orbit the Earth dozens of times per day,” a military official said. “This allows for frequent monitoring of targets and the use of sensors tailored to specific targets to detect North Korean provocations in a multidimensional way.”

The EO-IR Unit 1 orbits at an altitude of 400 to 600 kilometers (248 to 372 miles) in a sun-synchronous orbit, passing over the Korean Peninsula twice daily at fixed times.

While it excels at identifying ground targets under consistent lighting conditions, its performance is limited by weather — an issue given that 70 percent of the peninsula's skies are cloudy year-round.

In contrast, SAR satellites operate by emitting radar signals and receiving reflections. They follow inclined orbits optimized for revisiting specific regions and pass over the Korean Peninsula four to six times per day. Although SAR images require additional expert analysis, they can capture imagery regardless of weather or time of day, offering all-weather, day-and-night coverage.

Once Unit 4 is stably placed in orbit, only Unit 5 remains to complete the 425 Project. Once fully operational, the satellite network will allow surveillance of North Korea and the surrounding region at two-hour intervals.

The military plans to complete the launch of Unit 5 within this year and then proceed with a follow-up project to secure more than five mid- to large-sized satellites and 40 to 50 ultrasmall satellites by the early 2030s.

When complete, this expanded system will make it possible to observe North Korea at 30-minute intervals.

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.

BY LEE YU-JUNG,LEE KEUN-PYUNG [[email protected]]