#长文创作激励计划#
On a sunny afternoon in January 1997, an incredible "visitor from the sky" event was staged in Tulsa City, Oklahoma, USA!
Lottie Williams, 52, is taking a leisurely walk in the park. Suddenly, a metal fragment weighing several kilograms fell from the sky, like a thrilling scene from a movie, and hit her directly in the shoulder!
Luckily, the lady was only slightly injured, which was thrilling and fortunate. Later, the investigation found that the space junk that caused the accident came from a decommissioned Delta 2 rocket.
After the rocket was launched in 1996, the wreckage re-entered the atmosphere, which eventually led to the "catastrophe from the sky".
This incident is the first case in history of space junk directly injuring people, but it is definitely not the last, which also sounded the alarm for all mankind from space junk!
Delta 2 rocket
Where does space junk come from?
According to the latest data from the European Space Agency (ESA), by 2020, a staggering amount of space junk had accumulated in Earth's orbit, with 34,000 pieces of debris over 10 centimeters, 900,000 pieces of debris between 1 and 10 centimeters, and more than 100 million pieces of fragments smaller than 1 centimeter.
The debris is speeding through orbit at breakneck speeds, reaching kilometers per second, posing a huge threat to satellites, space stations, and other spacecraft. In 1979, the U.S. Skylab re-entered the atmosphere and crashed in Australia, causing no casualties but sparking global attention to space debris.
Space junk mainly comes from the wreckage of abandoned satellites, rockets, and various space missions. Every launch mission inevitably produces debris, some of which can float in orbit for years, if not decades. These high-speed flying debris may create more debris after colliding with other objects.
This phenomenon is known as "Kessler syndrome" and is a theory proposed by NASA scientist Donald Kessler in 1978.
The theory describes that when the amount of debris in space accumulates to a certain level, the collision between them triggers a chain reaction. Imagine a piece of debris hitting another and splitting into more smaller pieces, which in turn may continue to hit other objects, and so on.
In 2007, China conducted an anti-satellite test and successfully destroyed an abandoned weather satellite with a missile. However, the test came at the cost of producing more than quite a few large pieces of debris, which in some way exacerbated space junk. In orbits flying at high speeds, the debris could pose a threat to other satellites and the International Space Station.
Another striking event occurred in 2009. At that time, an American star Iridium collided with an abandoned Russian satellite over Siberia. The collision created thousands of pieces of debris, further increasing the amount of trash in low-Earth orbit. This is also the first time in human history that two artificial satellites have collided in orbit.
NASA's assessment is very worrying! They point to the density of debris in low Earth orbit, which is already close to the tipping point of Kessler's syndrome. There may be more collisions in the future, leading to a further spike in the amount of space junk!
As the amount of space junk continues to grow, if similar collisions occur in the future, not only could people on the ground be at risk, but also could cause damage to satellites and other important spacecraft, which in turn could affect critical services such as communications, navigation, and weather monitoring.
Where do these mysterious objects come from?
NASA reports that there are more than 20 potential collisions between space junk and satellites or space stations every year! Most of these thrilling and passing events are less than a kilometer away!
To protect against these potential risks, the ISS has to make orbit adjustments two to three times a year.
Since 1957, when humans began launching artificial satellites, more than 560 satellites around the world have been damaged or scrapped due to space junk or collisions with other satellites. Each collision can lead to the retirement of a satellite and its services, with losses in the hundreds of millions, if not billions, of dollars at a time.
Historically, such a tragedy befell France's Cerise satellite in 1996. Unfortunately, it was hit by an abandoned piece of rocket wreckage, which damaged the antenna, and while the satellite was still barely functioning, its functionality was greatly reduced. In 2009, the American Iridium-33 collided with the Russian Cosmos-2251 satellite over Siberia.
The collision had a severe impact on Iridium's communications network services, and the company had to adjust the satellite's orbit frequently to cope with the situation. In June 2016, the window of the International Space Station also suffered a thrilling impact.
The perpetrator was a tiny piece of space junk less than 1 mm in diameter. Although the window is not broken, the glaring crack is like a mirror, reflecting the great threat that space junk poses to the space station and astronauts.
With the increasing frequency of space exploration activities and the proliferation of commercial satellite launches, such collision events are likely to become more common in the future. This reminds us that countries around the world must work together to develop and implement effective measures and policies to tackle the problem of space junk and ensure the safety of Earth and space.
This country bears the greatest responsibility!
When it comes to space junk, the United States is undoubtedly one of the "big players". As one of the pioneers of space exploration, the United States has carried out a large number of launch missions, leaving behind countless abandoned satellites and rocket wreckage.
According to statistics, as of 2020, more than 8,000 pieces of space junk left by the United States in Earth orbit are more than 10 centimeters in size.
The Soviet Union, the former superpower, has been in the field of artificial satellites since 1957, and by 2020, the amount of space junk in Russia has accumulated to more than 7,000, all of which are larger than 10 centimeters. In 2019, when the Long March 5B rocket was successfully launched, part of the rocket wreckage returned to Earth, which also almost caused a safety threat on the ground.
From the available data and cases, space junk generated by space activities by the United States, Russia, and China occupies a prominent place. In order to meet this challenge, the United Nations Office for Outer Space Affairs and the International Telecommunication Union (ITU) are actively formulating relevant regulations to reduce the production of space junk and jointly protect the blue sky above us.
Do countries have an effective system for space junk?
Tech giants and tech companies have also invested in research and are working to develop various ways to clean up space junk.
In 2018, the Fraunhofer Institute in Germany has preliminarily realized the use of laser technology to clean up space debris. They used laser beams to push small debris away from dangerous orbits and reduce the risk of collisions, and the initial experimental results showed great potential. In 2018, the European Space Agency (ESA) teamed up with the University of Surrey in the United Kingdom on a mission called Remove DEBRIS.
This mission included several technical tests of space junk cleanup, one of which was the use of the Space Junk Net Capture System, as mentioned above, to capture space junk. During the test, the space junk network successfully captured simulated space debris. It seems that cleaning up space junk can be regarded as a new big business in the 21st century!
In order to clean up space debris, NASA has worked with international partners to jointly plan a more systematic and far-reaching cleanup plan, hoping to build a complete mechanism for monitoring and cleaning up space debris through international cooperation. The U.S. space surveillance network has played a pivotal role in space junk monitoring.
As of 2020, the network has successfully tracked more than 26,000 pieces of space junk larger than 10 centimeters, providing vital data support for global space activities and ensuring the smooth progress of space exploration.
In 2019, the European Space Agency (ESA) also announced an ambitious plan called Clear Space-1. The mission, which is expected to lift off in 2025, has a unique mission dedicated exclusively to cleaning up space junk. The core mission of the "Space Cleanup" is to lock down and remove the wreckage of a Vespa upstage rocket adapter that was left in space in 2013.
China's "Space Debris Capture and Processing Technology"
Of course, our country has not stopped, our Tiangong-1 and Tiangong-2, during their orbit, the Aerospace Science and Technology Group has carried out a large number of space debris protection and avoidance experiments. By monitoring space debris and adjusting its orbit, the Tiangong space station has successfully avoided multiple collisions with space junk, demonstrating its strength in space debris monitoring and avoidance.
Wukong's main mission is to explore the traces of dark matter, but in the process, its design and operation experience provides valuable data and reference for our future space garbage cleanup work.
Since its launch in December 2015, Wukong has been in space for more than five years, collecting a lot of data about the space environment. This data is very important for us to monitor and clean up space garbage!
The "Fifth Academy of China Aerospace Science and Technology Corporation" has directly carried out a major project called "Space Debris Capture and Processing Technology". The technology uses a mesh device and a flexible robotic arm to capture the trash floating in space. In 2016, they conducted a series of experiments on the Tiangong-2 laboratory, simulating the capture of space debris with a robotic arm, and the effect was quite good, and a significant breakthrough in technology was also made.
From these experiments, it is not difficult to see China's determination and strength in space junk cleanup technology. The market size of space junk cleanup in the next decade is expected to reach a staggering billions of dollars! The rise of the space junk cleanup market will provide important support for the security and sustainable development of the global space environment.
Resources:
The Problem of Space Junk, Coal Industry Press, 2001