What Are the Chances of You Getting Hurt by Space Debris? [Reading Science]

[Asia Economy Reporter Kim Bong-su] "Is there an 'Owl' that protects the safety of the Korean Peninsula's sky 24 hours a day?" This is what I learned when I visited the Korea Astronomy and Space Science Institute (KASI) in Daejeon on the afternoon of the 10th. Designated in 2015 as a 'Space Environment Monitoring Agency' to prepare for the fall of threatening materials from space such as asteroids and space debris, KASI houses the Space Hazard Monitoring Center. The eyes and ears of this center are the Optical Wide Field Patrol network, which KASI refers to by the similar English acronym 'OWL-Net.' It consists of 0.5m diameter wide-field telescopes installed in five locations: Morocco, Mongolia, the United States, Israel, and Korea's Bohyeonsan. Their main mission is to track and monitor fast-moving artificial satellites and space debris falling to Earth.

Fifteen researchers work around the clock to safeguard the sky over the Korean Peninsula. Their efforts reassured the public by monitoring and analyzing in real time the fall of debris from China's 20-ton Changzheng (Long March) 5B rocket on the 9th, confirming that there was no possibility of it falling on the Korean Peninsula. Please refer to the article introducing this place ([Reading Science] Space Debris Monitoring 'Owl' Protects the Korean Peninsula Sky 24 Hours). Today, I would like to share stories that could not be fully covered in the article.

◆What is the actual probability of injury from space threats?

The issue of space debris falling became a hot topic during the fall of the Changzheng 5B rocket debris. One of the most common questions people have is: what is the actual probability of suffering damage? According to KASI, as of now, the probability of death or injury caused by falling space objects is between 1 in 10,000 and 1 in 270,000 per day. This is an 'extremely low probability,' estimated to cause harm to about one person worldwide over 100 years. This was also the basis for China's confident claim, in response to international criticism calling it "irresponsible," that "everything will burn up and cause no harm." Since 70% of the Earth's surface is ocean, even if fragments remain and fall, most land in the sea. Moreover, South Korea occupies only 1/5,100 of the Earth's total surface area. However, the expected rapid increase in space debris is a variable. Private space companies like SpaceX, led by Elon Musk, who has become a 'Bitcoin villain,' plan to launch tens of thousands of small and medium-sized satellites into space within the next decade. Many of these will fail from the start, and most are low Earth orbit satellites that will fall to Earth after their lifespan ends. Although there are technologies to move satellites to orbits that do not fall to Earth using fuel after their lifespan to maintain usable atmospheric space, these are costly. There is also a method to guide them to fall into the 'spacecraft graveyard' located at a point in the South Pacific, but this also requires cost and technology.

◆There have been cases of damage

Does this mean there has been no damage? There have been. On January 22, 1997, Lottie Williams, who lives in Tulsa, Oklahoma, USA, famous as the filming location of the movie 'Minari,' witnessed a burning fireball in the sky around 3:30 a.m. and was struck on the shoulder by some material. This material was later confirmed to be a fragment of space debris. She was lucky. The largest piece of space debris recently found without burning up weighs up to 250kg. The falling speed ranges from at least 30 to 300 km/h. If it hits a person or building, it would cause fatal damage.

There have been many other cases where large debris fell and startled people. On September 8, 2004, NASA's launch test site located in the Utah desert, USA, was shocked when the solar wind probe Genesis crashed at a speed of 300 km/h. In December 1994, a 2.4m fragment of the Russian Cosmos 2267 satellite fell in the Cosala region of Mexico, frightening people, and in August 2011, debris from a Russian rocket was found off the coast of Tobago Key, Florida, USA.

◆Is South Korea safe?

The Earth's atmosphere is expected to become filled with large and small space debris in the future. Due to Earth's gravity, space debris located below 1,500 km orbit will fall to Earth within tens to hundreds of days. The important thing is to analyze and prepare for the exact time and place of space object falls, but currently, accurate analysis and prediction are only possible 1 to 2 hours before the fall. Generally, about a week before the fall, the date can be roughly predicted with an error margin of ±1 day, and one day before, the prediction error is ±90 to 135 minutes. Even the United States, which has the world's best analysis technology, can only predict within ±9 to 12 minutes until just before the fall. Therefore, prior preparation is difficult. After the fall is confirmed and the fall location is identified, the public needs to continuously monitor and prepare for the situation as it unfolds moment by moment.

This content was produced with the assistance of AI translation services.