The future drawn by “Seungri-ho”…”Space garbage that will threaten humanity”

[사이언스 라운지] ‘Seungri-ho’, a popular movie recently, has’space cleaners’ as the main characters. Although it is a space scavenger, he is more of a space junkie’hunter’. They collect debris such as broken satellites and rocket debris that are rapidly orbiting around the earth by spacecraft, bring them to a recycling center, and receive’scrap price’. ‘Seungri-ho’ is not the first time space trash has appeared in a movie. In the movie’Gravity’, an astronaut who was repairing a space telescope crashes into space garbage and becomes a’space lost’.

Space debris does not stand still like debris on Earth. So it is dangerous. The average speed of space debris is 7 km/sec, more than 7 times faster than a bullet. Even the smallest fragments can become a weapon capable of destroying satellites, space stations, and spacecraft if their speed increases. In particular, the collision speed is faster when hitting a spacecraft flying from the other side. If space debris with a diameter of about 1cm flies at a speed of 10km per second and collides, large satellites will also break more than half. In 1996, the French satellite Serize was struck by a rocket wreck and ceased to operate. This is the first satellite damage caused by space debris. If a manned spacecraft collides with such space debris, it could lead to personal injury.

As space debris increases, there is a worst case scenario that in the future, humans will not be able to explore space as well as shoot satellites. In 1978, NASA scientist, Dr. Donald Kessler, argued that when space debris collides with another satellite, another space debris is created, which causes a chain reaction, which can cause the entire orbit to be covered with space debris. Also came out. Some of these concerns can become a reality. According to The Economist, a British weekly magazine, the number of times satellites collided with space debris in the last three years has more than doubled compared to before.

Space debris can threaten humanity living on Earth. In 1979, the first U.S. space station’Skylab’ fell to Earth at the end of its life. The Skywrap, weighing 80 tons and measuring 27 meters in length, was mostly lost in the course of the fall, but a part that was not completely burned fell to Australia. Like Skylab, there is always the possibility that the debris from space stations and satellites used by mankind will orbit after the end of their life and gradually fall to Earth by the Earth’s gravity. Falling space debris meets the atmosphere at an altitude of 80 km, with a fall speed of 25,000 km/h. Most of the artificial space objects are burned during the process of entering the atmosphere due to the frictional heat caused by the tremendous speed. However, some parts, including parts with a high melting point, do not disappear and fall to the surface of the earth.

According to NASA, as of 2021, there are about 23,000 pieces of space debris measuring 10 cm in size in Earth’s orbit. There are 500,000 pieces of space debris less than 10 cm, and more than 100 million pieces of ultra-fine space debris with a diameter of 1 mm or more.

In order to solve the problem, real’Seungri’s are coming out around the world to dispose of space debris. The first place to start cleaning is Europe. The European Space Agency of the European Union entrusted space cleaning to the Swiss space cleaner’Clear Space’. They launch a capture spacecraft equipped with four robotic arms in 2025 to capture space debris and enter the atmosphere. The first target is the satellite launch vehicle Vespa, which has been left in Earth’s orbit since 2013. It first finds space debris through an artificial intelligence (AI) camera mounted on the capture spacecraft, then uses four robotic arms to pick up the debris, then drags it down to the atmosphere and burns the space debris. This is repeated several times to dispose of about 100 kg of space waste. It costs about 120 billion won in Korean money.

There is also a way to collect space debris through nets and harpoons. In 2018, researchers from European aircraft manufacturer Airbus and British Surrey University launched an experiment to capture real space debris by launching a cleaning satellite called’Remove Debris’ that retrieves waste artificial satellites with a harpoon-shaped tool. They succeeded in wrapping the’space garbage model’ in space with a net. However, because the net itself was not anchored to the scavenging satellite, it was not successful in getting the target out of orbit. Since then, they are focusing on capturing space debris with harpoons. It shoots up a harpoon made of titanium, catches the targeted space debris, and then drags it to the atmosphere and burns it away. Airbus believes that using a harpoon could be an easier way than a robotic arm.

Japan’s space sweeper’Astroscale’ collects metal-based space garbage by floating a satellite loaded with a giant magnet and burns it in the atmosphere. The idea is to make profits by cleaning space’paths’ by receiving orders from countries or companies that operate space stations or satellites.

Sky Perfect JSAT, a Japanese satellite communications company, is developing a satellite that cleans space debris using lasers with the goal of commercialization in 2026. It is a method of evaporating the surface of space debris by firing a laser from a distance of several tens of meters, moving it to a desired place, and inducing it to enter the atmosphere and burning it. Through this, the company explained that it will be able to dispose of space garbage weighing about 100 kg.

Russian space startup (early venture company) Start Rocket is developing a satellite that collects space garbage using a technology called’Foam Breakes Catcher’. Cylindrical satellites aimed at launch in 2023 as early as 50 kg are a method of discharging sticky polymer foam (polymer foam) where space debris is collected, causing garbage debris to stick to it, then dropping them into the Earth’s atmosphere and burning them with frictional heat Use. The advantage is that the price is cheaper than the method using a harpoon and net. The company is also pursuing a project to make’ultra-large billboards’ like constellations by launching Cubesat (micro satellites) into the sky.

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