October 16, 2020
Since humans began to explore space, an unavoidable problem has accumulated over time and has become more and more dangerous, that is, the shocking amount of space junk poses a security threat.
At a high place more than 1,000 kilometers away from the earth, two pieces of space junk floating freely in space moved closer to each other, getting closer and closer.
One is a long-decommissioned and abandoned Russian satellite, Kosmos-2004, which is incompletely broken, and the other is the wreckage of the Chinese Long March rocket that completed its mission. At one time, they were only 25 meters apart or even closer.
If they collide or “bear hug”, more space metal pieces will be produced, scattered into the air and floating freely, staying in this high space for a long time.
Tracking studies on this type of space junk found that they generally weigh more than 2.5 tons and have a relative speed of close to 15 kilometers per hour. The consequences of collisions are considered catastrophic and more space junk will be produced.
This high level of space debris poses an unignorable threat to operating satellites and space stations.
LeoLabs, a US Silicon Valley startup that tracks space junk from the ground, witnessed the dangerous close encounter between the abandoned Russian satellite and the wreckage of a Chinese rocket in mid-October, and found that the two finally passed by.
At that time, below them was Antarctica. LeoLabs said there were no signs of debris in Antarctica, and the two mounds of metal floating in the air could still be traced. LeoLabs provides orbit mapping services with a radar network developed by itself.
According to estimates by Dr. Moriba Jah, an astrodynamicist distributed by the University of Texas at Austin, and Aerospace Corporation, a well-known consulting company in the industry, the Kosmos-2004 and the remnants of the Long March rocket are only separated by Said hello from a distance of about 70 meters.
Space junk is accumulating day by day, and congestion in low-Earth orbit is serious. Scientists have screamed that the limit is approaching 10 years ago, and the potential safety risks are shocking.
Space junk mainly refers to abandoned satellite remains and other metal fragments that have not been completely incinerated. It is currently estimated that there are approximately 900,000 pieces of space debris, ranging in size from fingernails to bowling balls, orbiting at high speed in low earth orbit.
They pose a great threat to satellites, rockets, and space stations. On average, one satellite is destroyed by space debris every year.
As more and more satellites take off, the possibility of collisions with space junk is increasing. In addition to the thousands of commercial, military, and scientific research satellites already in the sky, thousands of satellites will be launched in the next few years.
According to the European Space Agency’s annual report on the state of the space environment in October 2020, an average of 12 space junk accidents have been observed every year in the past 20 years, including orbital explosions caused by abandoned spacecraft and remaining fuel and batteries on rockets. Such accidents are on the increase.
Space debris collides and triggers a series of collisions, resulting in the overall pollution of the satellite orbit, the “Kessler effect”, which is also a major threat.
In 2007, the number of space debris soared because China deliberately destroyed the “Fengyun-1C” weather satellite in an anti-satellite device test. Two years later, the US “Iridium 33” communications satellite collided with Russia’s scrapped “Cosmos 2251” satellite. Both of these incidents had lasting consequences for a long period of time.
According to data from the National Aeronautics and Space Administration (NASA), the total amount of man-made matter in Earth’s orbit currently exceeds 7,600 tons; the US Space Surveillance Network (SSN) is tracking more than 20,000 pieces of larger debris.
Experts pointed out that a large part of the current space junk is fragments of Zenit rockets from the Soviet era.
Tracking and monitoring
Efforts to clean up space junk have been uninterrupted in the past few decades, but it is generally believed that this aspect still faces major technical and economic challenges. Disputes between major aerospace powers over who creates more space junk continue, and relevant international consensus or regulations have yet to be formulated.
At the same time, some analysis pointed out that the space debris monitoring and tracking market will reach 100 million pounds by 2035.
Traditional methods of tracking space debris include radar and optical instruments.
The US Air Force’s “Space Fence” project uses radar to track approximately 200,000 pieces of space junk.
In August 2014, the US military giant Lockheed Martin signed a contract with the Australian Optoelectronics Technology Company EOS to cooperate in tracking space debris, using Guanxue and laser technology to search for, track and identify space debris. The cooperation includes a new tracking station in Australia.
In December 2017, a toolbox-sized debris sensor was connected outside the experimental cabin of the International Space Station, which orbited the earth to detect millimeter-sized debris and the data of debris hitting all materials to distinguish whether the impactor was a space meteorite or man-made garbage. .
Russia, another space power, signed an agreement with Brazil to set up a new space debris tracking telescope.
In addition to government-level projects, the private sector is also increasingly involved in space junk detection and tracking, including setting up or operating ground-based sensor systems and space telescope networks, and selling relevant data to satellite operators.
After mastering the whereabouts of the debris, the impact can be avoided by changing the trajectory of the debris, but the amount of debris is huge, the prevention is relatively difficult, and it is difficult to deal with all debris and garbage.
Many countries and some private companies are testing a variety of methods to remove space junk, including launching “harpoon” traps, magnets and large nets to capture space junk.
Europe launched a satellite in June 2018 to test the possibility of space garbage cleaning and recycling. The key technologies tested include visual navigation systems, nets and forks to capture debris, and devices that force debris to decelerate and fall out of orbit into the atmosphere.
The coordinating agency for this mission called REMOVEdebris is the Surrey Space Center in southern England.
The “Space Harpoon” can crush larger space junk and is similar in size to a pen. The crushed garbage enters the atmosphere through the garbage collection network and derailment device and burns itself.
If the REMOVEdebris installation is successful, more missions will be launched in Europe in the future, and it is also hoped that commercial organizations will follow up and participate.
The European Space Agency chose to use the scrapped satellite test through the e.deorbit spacecraft to safely remove objects that are not under ground control from orbiting the Earth.
Sensors are installed on the spacecraft to safely approach the satellite and dock with controlled objects such as the International Space Station.
In February 2012, Swiss scientists launched a space-junk-clearing satellite program. The mission of the “CleanSpace One” satellite is to collect space junk in orbit while orbiting the earth, and then carry the junk back to the earth and return. These garbage will be burned in the atmosphere.
In 2016, Japan launched the “Stork” cargo spacecraft to transport supplies to the International Space Station and test space junk removal technology.
During the space flight, the spacecraft releases a metal guide cable to make it adsorb to the surface of the space junk, and discharges to it through the metal guide cable, using the principle that an object will move when it is energized in a magnetic field to slow it down. After being lower than the speed required to revolve around the earth, it fell into the atmosphere and burned by friction with the atmosphere.
The European Space Agency plans to launch the first space mission to remove debris from Earth’s orbit in 2025.
The British Space Agency hopes that British companies will actively participate in the space junk tracking market with the aim of attracting more satellite operators to settle in the UK.