At about 7:30 a.m. EDT on March 4, a piece of debris from a rocket that had been in space for seven years and weighed about 4 tons slammed into the far side of the Moon at a speed of nearly 5,800 miles (10,944 kilometers) per hour. The circumstances of the impact are not yet known. And may not observe the crater for weeks or even months.
“Scientific American” magazine pointed out that this is the first accidental case of space junk hitting the Moon in space, and it expects that the diameter of the impact crater may reach about 20 meters. NASA has said it is enlisting an orbiter to arrive at the accident site to confirm details of the impact site. In fact, for the past six decades, like the rockets, satellites. And other vehicles and payloads that have continuously deploy by aerospace powers such as the United States Russia (the Soviet Union). And others have come to an end, and spacecraft have been crashing into the Moon to dispose of them or to study the craters they formed—resulting in the accumulation of space junk and severe congestion in low-Earth orbit.
The reviews of space junk events in recent years
In November 2021, South Korea’s “Arirang 3” satellite was nearly hit by a piece of high-speed space junk. The closest distance between the garbage and the satellite was only 62 meters at one time, and the satellite escaped through an emergency ascent; in early February this year, Musk’s SpaceX company had an accident during the launch process. Due to a geomagnetic storm, Of the 49 Starlink satellites launched, 40 fell into the Earth’s atmosphere and burned up. Although scientists have been calling for the limit to approach ten years ago, disputes between countries over who creates space junk continue, relevant international consensus or regulations have not yet been formulated, and the clean-up of space junk has become an unsolved case.
Some analysts pointed out that it expects that by 2035, the market size of space debris monitoring and tracking will reach more than 100 million U.S. dollars. Gao Enyu, founder and general manager of “Micro-Nano Star,” a commercial satellite and ground application developer, recently. Said that the on-orbit management of space debris caused by spacecraft in space needs to carry out in a unified manner, and this is not a matter of one country. More It is a matter of all humanity. However, Gao Enyu also pointed out that there is currently no demand for space resources that are so crowded that ground parking and collisions in space are very low probability. NASA scientists have said that the chance of a collision in an area is as low as a few in 10 million.
The total amount exceeds 8,400 tons. What impact will space junk cause?
The first thing to be clear is that space junk mainly refers to abandoned satellite debris and other metal fragments that have not been entirely incinerated. With the retirement of spacecraft, natural disintegration, or accidental collision, these artificial wastes and their derivatives that countries cannot use to land in low orbit and fly around the Earth. Still, they are useless, so they are collectively referred to as “space junk.” It estimates that there are currently about 900,000 pieces of space debris ranging from fingernails to bowling balls. And they are mainly concentrated in orbits at an altitude of 500 kilometers to 800 kilometers, which are also the orbits in which active satellites operate.
According to NASA and the U.S. Space Surveillance Network (SSN), since humans stepped into space, more than 27,000 pieces of space debris or “space junk” with a total weight of more than 8,400 tons have been produced. Much of this junk came from scattered rocket parts. Space junk has not existed since ancient times. At least before 1957, space was very “silent.” However, with the economy’s needs, national defense, and scientific research, human beings have begun to develop space resources continuously, and various spacecraft have come to outer space. Except for extraterrestrial exploration, such as Mars, lunar exploration, etc., most satellites are concentrated around the Earth, while aircraft A lot of debris is inevitably generated. According to media statistics, the top five source countries of this “space junk” are Russia, the United States, China, France, and India.
They run at a speed of nearly 30,000 kilometers per hour, posing a particular threat to satellites, rockets, and space stations. On average, one satellite is destroyed by space debris every year. And space debris collides and triggers a series of impacts until all spacecraft is destroyed, which will lead to the overall pollution of satellite orbits, which is the “Kessler phenomenon.”
While today was the first time space junk collided with the Moon, it wasn’t the first time an artificial object crashed. As early as 1985, the Soviet Union (Russia) used a missile to hit an observation satellite launched by the United States in 1979. This anti-satellite weapon directly threatened the United States in the Cold War between the United States and the Soviet Union. By 1996, a French satellite had been hit and damaged by debris from a French rocket that exploded a decade earlier. And the debris crashed on the Moon. In 2007, space debris soared, and China destroyed its Fengyun-1C weather satellite, launched in 1999, in a test. Two years later, in 2009, the U.S. communications satellite Iridium 33 collided with Russia’s defunct Cosmos 2251 satellite, adding more than 2,300 traceable large pieces and smaller pieces. Both events had lasting consequences over a long period.
Today, the accidental collision between rocket debris and the Moon was discovered by the Catalina Sky Survey Telescope in the United States and was subsequently named WE0913A. However, WE0913A does not orbit the sun like an asteroid but orbit Earth. For this reason, American astronomer Bill Gray suspected that it was an artificial object and first predicted in March 2015 that the thing would be similar to the Moon. Collide. Because it hit the far side of the Moon, scientists could not observe the crater for some time until satellites orbiting the Moon were in suitable orbits to help them better understand scientific phenomena under the Moon’s surface. And impact effects. The Moon litters with naturally formed impact craters, estimated to number more than 100,000.
However, there is currently some controversy over the information on the rocket’s debris that hit the Moon. Previously, Bill Gray pointed out that the rocket debris may have originated from a Falcon rocket launched by Musk’s SpaceX in 2015. Still, some analysts believe that it is an aircraft from China. It can only be determined this controversial conclusion until the plane finds the impact site. It is worth mentioning that Jonathan McDowell, a scientist at the Harvard-Smithsonian Center for Astrophysics in the United States, pointed out that the number and risk of “space junk” are increasing. He found that about 3% of the more than 800 Starlink satellites SpaceX launched into the sky failed due to failures, and the resulting space junk, that is, the “dead” satellites produced, may eventually reach more than 1,200.
Solution: tracking and monitoring, removing garbage
In the face of space junk, all countries take active actions, from avoidance to prevention and protection monitoring to removal. At present, the most effective solutions for human beings to solve the problem of space junk mainly include tracking monitoring and garbage removal. Among them, traditional methods of tracking space debris include radar and optical instruments.
In August 2014, the United States proposed the “Space Fence” project plan and let the military giant Lockheed Martin and the Australian optoelectronic technology company EOS sign a contract to track space debris. Using caves and laser technology to search, track and identify space debris, The partnership includes building a new tracking station in Australia that will use radar to track some 200,000 pieces of space junk. In December 2017, scientists developed a space tracking device that connected a toolbox-sized debris sensor to the outside of the International Space Station’s experimental module, orbiting the Earth with the space station, detecting millimeter-scale debris, and data on waste hitting all matter. To distinguish whether the impactor was a space meteorite or artificial junk.
The space power Russia signed an agreement with Brazil to set up new space debris tracking telescope, including establishing or operating a ground sensor system and a network of space telescopes to track data related to space debris. On the other hand, the vast amount of space junk is becoming more and more difficult to follow. At present, countries are testing various methods to remove space junk, including launching “harpoon traps,” magnets, and large nets to capture space junk.
In 2016, Japan launched the “Stork” cargo spacecraft to test space junk removal technology while delivering supplies to the International Space Station. During the space flight, the spacecraft released a metal guidewire to make it adsorb to the surface of the space junk, discharge it through the metal guidewire, and use the principle that objects will move after being electrified in a magnetic field to slow them down. After falling below the speed required to orbit the Earth, it fell into the atmosphere and burned up by friction with the atmosphere.
In June 2018, Europe launched a satellite to test the possibility of cleaning up space junk. Key technologies tested include a visual navigation system, nets and prongs that capture debris, and devices that force the trash to deorbit and fall into the atmosphere. Among them, the “space harpoon” can crush giant space junk with a size similar to a pen, and the waste enters the atmosphere directly through the collection net and deorbiting device and burns itself.
In 2019, the European Space Agency announced that it had commissioned a company called Clearspace to carry out the first human space junk cleaning mission in 2025, which will carry out by the cleaning satellite Clearspace 1. The satellites orbiting the Earth, patiently weaving the web, slowly approaching the garbage, capturing them, and then turning on the return thruster will carry the space garbage back. The trash will be burned in the atmosphere during the return process and fall back to the Earth together.
Gao Enyu said that the current global action to clean up space junk has a specific effect. The satellite products developed by China can ensure that they continue to operate normally in the target orbit. In the end, they will automatically fall, enter the atmosphere and then burn up, thereby reducing the risk of “space junk.” “The way (our satellite) enters orbit is different from SpaceX’s Starlink. Starlink is a rocket that first sends the satellite into 200-300 kilometers. Then, the satellite has to climb another 300 kilometers by itself and enter 500-600 kilometers—the target orbit. The rocket launched by China directly sends the satellite into the target orbit of more than 500 kilometers. It does not need to fly to change its trajectory, so there is no possibility that the satellite may fail when changing orbit and thus stay in excessive rotation. Gao Enyu told the Titanium Media App that the space junk caused by Starlink is more driven by orbital change and the manufacturing process not reaching the highest level.
In his view, although satellites have a lifespan, Chinese satellites will be equipped with electric propulsion orbit change devices, which will automatically fall into the atmosphere at the end of the period. They will not produce space junk that affects the space station’s operation. However, Gao Enyu also emphasized that “space junk” must be managed with the normalization of deep space. “For satellites launched by China, whether within the system or outside the system, everyone is obliged to make their efforts to mitigate space debris,” he said.