[Reading Science] 'Owl' Space Debris Monitor Guards Korean Peninsula Sky 24 Hours

Visiting Korea Astronomy and Space Science Institute's Space Hazard Monitoring Center
Nation's Only Space Environment Monitoring Agency
Accurately Locates Debris from China's Changzheng 5B Rocket Reentry
Protecting Public Safety from Space Debris and Asteroids

[Asia Economy Reporter Kim Bong-su] "Article 34, Clause 6 of the Constitution - The state shall endeavor to prevent disasters and protect the people from their threats."

On the afternoon of the 10th, this constitutional phrase was encountered at the Sejong Hall in the main building of the Korea Astronomy and Space Science Institute (KASI) in Daejeon. Why would an institution that studies astronomy, that is, constellations and the universe, be talking about the Constitution? This question was soon resolved. KASI is the only ‘space environment monitoring agency’ in Korea that monitors, tracks, and issues warnings in real time about space objects such as space debris and asteroids that could potentially cause major disasters. When the 20-ton debris of China’s Long March 5B rocket fell on the 9th, causing global anxiety, it was KASI’s observations and analysis that reassured the public by stating, "There is no possibility of it falling on Korea."

On the third floor of Sejong Hall, there is the ‘Space Hazard Monitoring Center,’ which serves as the brain responsible for tracking and monitoring space debris and predicting risk levels. In a classroom-sized space within the center, a large screen was densely displaying space-related information collected domestically and internationally. The commotion caused by the Long March 5B debris fall a few days earlier was still evident that day. The largest screen showed the trajectories of satellites currently orbiting the Earth and whether they contained hazardous materials, while one wall was equipped with devices monitoring and tracking the current positions and trajectories of asteroids passing near Earth.

◇ The ‘Owl’ Protecting the Korean Peninsula

The green letters in the center of the screen reading ‘May 10 Safety’ caught the eye. According to a KASI official, this means that as of that day, there were no materials in space threatening the Earth, especially the Korean Peninsula. In another part of the center, there was a monitoring room for the ‘Owl (OWL-Net),’ which monitors the safety of the Korean Peninsula’s sky 24 hours a day. Of course, this is not an actual animal. OWL stands for Optical Wide Field Patrol. Since 2015, KASI has installed 0.5-meter wide-field telescopes in five locations?Morocco, Mongolia, the United States, Israel, and Korea’s Bohyunsan?to monitor the approach of space debris and asteroids threatening the Korean Peninsula, and this place serves as the command center for that mission.

Equipped with a high-speed mount, fully openable dome, enclosure, and remote automatic operation system, it is considered the most advanced monitoring equipment in the world. It can track and monitor artificial satellite objects and is the world’s first system to automate the entire process from observation planning to result analysis. Using this equipment, KASI observed and analyzed the final trajectory of the Long March 5B rocket debris on the 9th and concluded that ‘the Korean Peninsula is safe.’ Recently, it also captured images of Our Star 1, which was first built and launched by Koreans in 1992 and has since reached the end of its lifespan, drifting alone in orbit, informing the public of its status.

Another weapon KASI possesses is the ‘KMTNet (Korea Microlensing Telescope Network).’ This facility, equipped with 1.6-meter telescopes and wide-field CCD cameras, is installed in three locations: Chile, Australia, and South Africa, primarily for exoplanet exploration. Besides its main mission, it spends 135 days a year analyzing the physical characteristics of Earth-threatening asteroids. KASI also receives and utilizes near-Earth asteroid orbital data monthly from the International Asteroid Center.

◇ New Threat: ‘Space Debris’

Before this center was established and fully operational in 2015, the Korean government was helpless against threats from space. At best, it would tremble in anxiety after reading foreign news and feel reassured only after receiving notifications from NASA. A representative example is the public anxiety during the crashes of former Soviet nuclear satellites in 1978 and 1983, fearing a ‘radioactive firestorm.’

Threats from space are rapidly increasing. With the advent of the private space development era, the risk of falling artificial space objects, such as satellite debris, is also growing. Approximately 7,000 artificial satellites were launched from Sputnik 1 in 1957 until 2015, but since then, the U.S. private space company SpaceX alone has launched about 1,300 satellites, and the number authorized for launch has reached 12,000. With the full-scale opening of the satellite positioning system (GPS), space internet, and high-speed communication services (6G) era, tens of thousands more satellites will be launched into the sky.

Experts predict that these satellites, mostly in low and medium Earth orbit, will become so densely packed that further launches will be impossible, increasing the likelihood of collisions or malfunctions leading to falls. Even operational satellites, after their lifespan ends, will eventually fall to Earth unless they are above 1,500 km altitude. Most burn up upon re-entry, but satellites weighing over 1 ton leave 20-30% of their material as fragments that can cause damage when falling to the ground. As of July 2019, there were 19,740 trackable space objects larger than 10 cm and about 500,000 small objects larger than 1 cm.

Asteroids passing near Earth are also threatening. As of the end of last year, 2,155 asteroids with diameters over 150 meters have been discovered, while those under 140 meters are difficult to observe and even harder to statistically account for. Approximately one asteroid approaches closer than geostationary orbit (about 35,000 km) every five years. Although small, asteroids between 10 and 50 meters in size have enough destructive power to wipe out a city.

The government began responding to space threats by revising the Space Development Promotion Act in 2014. In January the following year, KASI was designated as the ‘space environment monitoring agency,’ responsible for key tasks such as monitoring and notification. However, the OWL-Net telescopes have performance limitations, making it difficult to detect asteroids smaller than 140 meters in diameter. Although the system is automated, having only about 15 personnel dedicated to space monitoring and notification is also problematic. To enhance space observation capabilities, KASI plans to build a space debris monitoring radar system at Gamaksan by 2023. Additionally, a 1.5-meter class optical telescope for detecting Earth-threatening asteroids will be constructed in Chile by 2025.

Dr. Cho Joong-hyun of KASI said, "When China’s space station Tiangong-1 fell in 2018, we worked around the clock for four days. At the final stage, it passed over Korea and was temporarily included in the danger zone, which made us very tense. As a scientist, it is most rewarding when predictions are accurate and we feel responsible for the safety of the people."