Thousands of rockets and satellites have been launched from Earth into space since 1957. While most of these still remain in space, it is known that more of them will be launched into space in the future. While this increases space junk, it risks colliding rockets and satellites launched over time.
In addition to meteorites, there are also man-made debris in orbit. These include obsolete satellites and spacecraft, launch vehicle launchers, and weathering parts.
Some objects within a few hundred kilometers of Earth can re-enter the atmosphere after a few years. Most of these are destroyed by burning due to friction as they enter the atmosphere. However, garbage and satellites at an altitude of more than 36 thousand kilometers can continue to orbit the Earth for hundreds or even thousands of years.
In addition to the two satellites colliding causing a lot of space junk, some countries such as the USA, China and India can use missiles to destroy their own satellites. This causes thousands of fragments to spread into orbit.
Currently orbiting space debris poses no major risk to exploration attempts, but is seen as a major threat to other orbiting satellites.
A French satellite was hit by fragments from a rocket that exploded 10 years ago in 1996.
In January 2007, China destroyed an old weather satellite with a missile in an anti-satellite test, causing more than 3,500 pieces to scatter into orbit. This event increased the rate of traceable objects by 25 percent.
The first accident in which two satellites collided occurred on February 10, 2009. The private American communications satellite “Iridium-33” collided with the Russian military satellite “Kosmos2251”. While both satellites were destroyed, more than 2,300 fragments were exposed, some of which re-entered Earth’s atmosphere and disappeared.
In March 2021, the Chinese satellite shattered into pieces after the collision.
Satellites avoid collision with space junk
The satellites are trying to avoid space debris in their movement areas so that they don’t get hit. Every year, all satellites, including the International Space Station (ISS), have to move to avoid hundreds of collisions.
The ISS has maneuvered to avoid space debris 25 times since 1999.
A satellite of the European Space Agency also made its first move in September 2019 to avoid a collision with a large satellite constellation.
The ISS had to maneuver to avoid collision due to space debris from Russia’s anti-satellite missile test in 2021. In November 2021, ISS astronauts took shelter in the transport spacecraft as the space station passed near a space junk.
China’s scientific observation satellite was also in danger of colliding in January 2022 due to this test by Russia.
Plans by companies to launch new sets of satellites into space, especially for internet use, could lead to an increase in space junk. In this case, 50,000 more satellites may start moving in orbit, which may require more collision avoidance maneuvers in the long run.
Donald Kessler, a NASA scientist, suggested in 1978 that if too much space debris accumulates in orbit, it could create a chain effect, and that more objects could collide and form new space junk.
Kessler claimed that as a result, Earth orbit could become unusable in the future. While this idea may seem extreme, some experts worry that some variant of it may one day be realized. Therefore, it is stated that this situation should be avoided.
There are 28,160 objects in orbit.
According to data from the European Space Agency, more than 6,500 rockets have been launched within the framework of space activities that have continued for more than 60 years, resulting in 56,450 trackable objects in orbit.
About 28,160 of these objects remained in space and are tracked by the US Department of Defense’s global Space Surveillance Network (SSN). About 4,000 of these serve as active satellites.
SSN focuses specifically on low-orbit objects at geostatic altitudes ranging from 5-10 centimeters to 30 centimeters to 1 meter.
More than 560 fragmentation events have been recorded in orbit since 1961. It is stated that only 7 of them occurred as a result of collision and explosion of spacecraft.
However, collisions are expected to be the source of space debris in the future.
Today, it is estimated that the number of litter in space will increase, with the annual number of launches being around 110 and breaking/fragmentation 10-11 times a year. Increasing debris also increases the likelihood of collisions, which increases the fragments to form in orbit, posing even greater risk of collision.
As a result, the greater the number of litters, the more collisions will occur. But space debris isn’t a problem for exploration outside Earth orbit.
UN calls for out-of-date satellites to be removed from orbit
The United Nations (UN) requests all companies to remove satellites from orbit within 25 years.
But this causes confusion when some satellites’ missions fail from the start. In this case, the method of burning and destroying the satellites by inserting them into the atmosphere is generally preferred.
Experts say that if inactive satellites are removed from orbit, the problem of space debris in orbit can be alleviated in the future.