Where does space debris come from? What does it threaten? How to remove it?

Space debris is artificial objects or parts of objects that no longer function but remain in orbit around the Earth. They have a wide range

Where does space debris come from? What does it threaten? How to remove it?
Where does space debris come from? What does it threaten? How to remove it?

Space debris is artificial objects or parts of objects that no longer function but remain in orbit around the Earth. They have a wide range of sizes: from microscopic particles of dried paint to spent rocket stages.

Most space debris is in low Earth orbit, ie at an altitude of up to 2,000 kilometers above the surface. However, some of these objects are much higher, in geostationary orbit, located at a distance of 35,786 kilometers above the equator. Depending on the height, how long the space debris will last:

Objects below 600 kilometers above the surface will fall and burn up in the atmosphere in a few years, while above 1000 kilometers they can revolve around the Earth for centuries. The highest concentration of debris - at an altitude of 750 to 1000 kilometers.

How many such objects are in orbit now?

According to the European Space Agency, since the beginning of the space age, humanity has made more than 6,000 rocket launches, sending into orbit 11,370 satellites. There are now 6,900 satellites orbiting the Earth, of which only about 4,000 are still operational.

Currently, the US Space Surveillance Networks monitors 28,160 objects, but in reality there are many more. Statistical simulations show that 34,000 fragments more than 10 centimeters long, 900,000 objects ranging in size from 1 to 10 centimeters, and 128 million fragments ranging from 1 millimeter to 1 centimeter revolve around the Earth. The total mass of all objects in orbit is 9800 tons.

What exactly creates debris in orbit?

More than a third of the objects in orbit that are being monitored are satellites and rocket stages. They are the main sources of smaller fragments. Fuel residue explosions are the most common cause of their fragmentation. Under the influence of extreme conditions of the space environment details of steps or satellites are destroyed, leading to leaks or mixing of fuel components and eventually to an explosion. In addition, extreme ultraviolet radiation has a negative effect on the coating of spacecraft, peeling it off, resulting in orbits of micro particles of paint. Finally, sometimes astronauts working in outer space lose a variety of objects. For example, Edward White, the first American to go into outer space, dropped a thermal glove during this historic event, which then burned in the atmosphere.

How dangerous is space debris?

In low Earth orbit, space debris revolves around our planet at a speed of about 7-8 kilometers per second. However, the average speed of one object colliding with another is about 10-15 kilometers per second. This is 10 times the speed of the bullet. Therefore, collisions with even small fragments emit large amounts of energy.

Spacecraft are constantly hit by very small orbital objects up to a millimeter in size without significant damage, but fragments a millimeter or more in size are already at high risk. In addition, over time, a large number of collisions disables some of the devices.

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Most affected are solar panels, which are constantly attacked by the smallest particles that are not available for monitoring. For example, Hubble is affected.

In 2002, the European Space Agency replaced the telescope's solar panels and returned one to Earth. It clearly shows traces of almost ten years of bombardment with fragments of various sizes. The risk of a catastrophic collision with the wreckage for Gubble is about 1 in 185, it has almost doubled since the early 2000s.

There is also a risk of collisions for crew missions. In particular, the wreckage could crash into the International Space Station. However, its critical components, such as housing modules and high-pressure tanks, are securely protected. They can withstand the impact of debris up to 1 centimeter in diameter. However, if the chance of a collision is greater than 1 to 10 thousand, the ISS performs an evasive maneuver. This happens quite often, on average at least once a year.

Have there been significant collisions in space?

Since 1961, researchers have recorded 560 events of object fragmentation in orbit, and only seven of them have been related to collisions. But it is assumed that in the future the main incidents that will lead to the formation of debris will be the collision itself. The probability of an accidental collision of two large objects (more than ten centimeters in diameter) is very small. However, the chances are not zero.

The first recorded such event occurred in 1996. Then the wreckage of the European Arian rocket, launched ten years earlier, crashed into a working French microsatellite. He was injured, but continued to work.

On February 10, 2009, the worst such incident occurred when a working American satellite, Iridium-33, collided with a Russian Cosmos-2251, which was no longer working. It happened at an altitude of 776 kilometers over Siberia, the devices crashed into each other at a speed of 11.7 kilometers per second. As a result, both were destroyed and formed about 2,300 fragments that could be traced. Some of them have already entered the atmosphere and burned.

In addition, some countries have tested anti-satellite weapons. For example, in 2007, China destroyed its meteorological satellite while testing such weapons. This event alone increased the amount of traceable space debris by 25%, creating more than three thousand fragments. They will remain in orbit for decades.

The number of satellites in orbit will continue to grow. In particular, not only SpaceX and its Starlink plan to create "mega-constellations" from thousands of satellites for Internet coverage - Amazon has similar plans. Increasing the number of objects in space will inevitably lead to an increase in the number of fragments. It is believed that this can cause a chain reaction - the so-called Kessler's syndrome. The wreckage of the satellites, crashing into spacecraft, will create even more fragments. It is estimated that doubling the amount of space debris will quadruple the risk of a collision. Eventually, the Earth's orbit can no longer be used.

Is it possible to clear the orbit of debris?

Researchers offer many ways to remove debris from orbit. Thus, on March 20, 2021, the Japanese company Astroscale launched the ELSA-d mission. It sent two satellites into orbit: a small "client" and a "staff" that would catch a smaller spacecraft. Over the next six months, the system will conduct three tests: the "staff" will release the "client" and try to find him,

Using GPS navigation, and grab by magnetic docking. This mission aims to demonstrate such technology, but this solution is not suitable for small garbage.

In 2018, the UK launched the Remove DEBRIS satellite, which tested two other ways to clean up space debris: using a net and using a special harpoon. Japan's Aerospace Exploration Agency is proposing to use a long cable that will knock satellites out of orbit so that they end up in the atmosphere and burn up. The European Space Agency plans to launch the ClearSpace-1 mission in 2025, during which the satellite will try to capture the payload adapter left over from the Vega rocket.