What is junk space?

According to the Catalog of Objects Launched into Outer Space managed by the United Nations Office for Outer Space Affairs, a total of 12,298 satellites have been launched since the launch of the first human satellite in 1957. 2022). Of these, only 8,378 satellites (including operational and non-operational satellites) are in orbit, and the remaining 3,918 satellites were found to have failed to enter orbit. They are called “space debris” or “space debris,” including their own debris, missile fragments, or even expired satellites.

If the satellites that fail to enter orbit are low orbit satellites, they will gradually slow down due to atmospheric microscopic effects and either return to Earth or burn up naturally in most of the atmosphere. However, high-orbit satellites with long orbital lives can be a huge problem. This is because space debris orbits the Earth at a very high speed. Given that the kinetic energy is proportional to the square of the velocity, its destructive power increases exponentially.

Also, if a lot of space junk in orbit destroys satellites or other space junk, it could cause another explosion of space junk. According to the European Space Agency’s Office of Space Debris, there are more than 30 thousand large and small man-made objects orbiting our planet, including satellites, of which more than 300 million small objects are five times faster than a bullet at a speed of 30 thousand km / h. To fly through space quickly Given the rapidly increasing number of satellite launches, it is clear that the number of space junk will increase day by day.

Why clean up space debris?

If space debris is not cleaned up, satellite orbits can be covered with space debris, which will prevent human progress into space. In addition, if the use of satellites ceases due to the destruction of satellites, humanity may immediately fall into great chaos. Even if we think from an environmental point of view about predicting and preparing for the future climate using satellites, protecting the Earth and the environment in the future would also be impossible without satellites. Large pieces of space junk can pose a direct threat to Earth, such as the crash of the Chinese space station Ten Gong-1 in the South Pacific that caused great concern a few years ago. Therefore, missions to remove space waste eventually become missions for humanity.

The first proposals to solve space junk actually began in the late 1970s. But this is a problem in which the interests of states are intertwined, and it has become a problem that is difficult to solve because there is no suitable solution. The ideas that scientists have come up with to solve the space debris problem are very diverse. Representatively, various methods have been mentioned such as capturing space debris with a harpoon-like instrument or spreading a large net in outer space to capture space debris. .

China’s SJ-21 satellite cleans up space debris

At a conference recently hosted by the Center for Strategic and International Studies and the Secure World Foundation, Dr. Brian Flewelling, designer of satellite tracking software and principal investigator at the private US company ExoAnalytic Solutions, presented some very interesting findings. . According to Dr. Flafling, in January, a Chinese spacecraft placed an inactive satellite into a “cemetery orbit, junk orbit, or disposal orbit: it used residual propellant to prevent the satellite from colliding with other satellites,” Flefling said. He said he caught something being thrown into a moving orbit.) It is considered one of the best ways to get rid of space debris because if it is dumped there, it is less likely to collide with active satellites and is much more effective than re-entering the atmosphere to dispose of the garbage. Dr Fleffling said the Chinese satellite SJ-21 was seen changing its orbit on January 22 to approach the inactive Compass-G2 (Chinese name: BeiDou-2 G2) satellite, and said the trajectory had changed. Over the next few days, the two space objects moved westward, appearing to dance, and on January 26, when the two moons separated, they said they had lost contact with G2 (see related video).

Compass-G2 is a spacecraft of China’s BeiDou-2 navigation satellite system, which failed shortly after its launch in 2009, and has been orbiting Earth as space junk for more than 10 years. On the other hand, SJ-21, which was launched in October 2021, is back in geostationary orbit (GSO: geostationary orbit or GEO: geosynchronous equatorial orbit; a satellite orbiting around the Earth at the same speed as the Earth’s rotation) above Congo Basin directly

The various efforts of mankind to protect the Earth in the end

The US Air Force expects the SJ-21 to be China’s OSAM satellite. Many space-related laboratories and agencies have been developing and enhancing various OSAM missions for decades, such as spacecraft designed to refuel, repair existing satellites, or dispose of space waste.

The European Space Agency (ESA) began trial run of the OSAM project in 1990 as a Geostationary Service Vehicle (GSV) program to capture and repair faulted geostationary satellites. It is considered one of OSAM’s successful missions. In addition, the European Space Agency plans to start its own garbage collection mission in 2025.

The Swiss Federal Institute of Technology in Lausanne, which will be responsible for the above-mentioned mission, proposes the “Clean Space One” mission, insisting on getting rid of space debris by launching a cleaning satellite, collecting space debris, and then returning it back to Earth’s atmosphere. However, since this is a one-time task, the very high cost is indicated as a drawback.

NASA also plans a number of additional OSAM missions, including OSAM-1 and OSAM-2. In particular, it was planned to equip OSAM-2 with a 3D printer for direct design and manufacture of parts.

Researchers at Purdue University in the United States insist on using the sail as a means to prevent future space debris (the mission’s official name: Spinnaker 3). A drag sail is a spacecraft that can open a thin, rectangular membrane like a sail into outer space. One regret is that it is impossible to attach a tug sail to the space debris currently orbiting the Earth, and before future spacecraft or satellites reach the end of their lifespan and become space garbage, they open them to reduce the speed of rotation and eventually return to the Earth’s atmosphere, the purpose It is causing a fall.

Japan launched the ELSA-d (Astroscale End of Life Services) mission designed to test space debris collection and removal technology in March 2021. According to Nobuo Okada, Astroscale founder and general manager of the mission, the mission includes a custom-made capture robotic arm that works in conjunction with two satellites, and a satellite for service and a satellite for the customer.

There is an attempt to create an integrated response system in preparation for the fall and collision of space objects through the “Space Hazard Preparedness Implementation Plan 2021”. Primarily, efforts are being made to develop technologies to prevent advance detection of space hazards and to broaden the space hazard preparedness base.

On the other hand, there are many concerns about the technology of disposing of space waste using OSAM missions. US Space Command Commander James Dickinson has expressed concerns that the technology could be used in satellite intake systems in the future.