“As satellite launches increase, so does the risk of collisions and damage from space junk”
Orbital space is a dangerous and hazardous environment for both humans and their machines. The lack of an atmosphere, extreme cold temperatures, and the risk of radiation and small meteorites and space dust all pose significant threats. In addition to these natural dangers, there are also man-made hazards in the form of space debris and satellites.
Since the 1960s, over 6,000 rocket launches have sent more than 50,000 satellites or satellite-sized objects into orbit. As of the end of 2022, there were 8,261 space satellites orbiting the Earth, with only 58% of them still active. In recent years, the number of satellites launched into orbit each year has increased significantly, with over 1,000 satellites being sent up annually and this number is expected to continue to grow.
This proliferation of satellites has contributed to the accumulation of space debris in orbit. Currently, there are over half a million pieces of debris larger than 100 mm (4 inches) in orbit that can be tracked. In addition to these larger pieces, there are over 120 million untracked objects smaller than 1 mm also in orbit. The larger debris, which is capable of damaging or disabling active satellites, and the smaller debris, which can cause less immediate damage but can eventually lead to major problems, pose a significant threat to operational satellites.
The increasing amount of debris in orbit has forced countries that launch expensive satellites into low Earth orbit (LEO) to place their satellites in orbits that are less likely to encounter large amounts of debris. However, the orbital space around Earth is vast, with each “layer” of orbit covering over 600 million square kilometers. Even in low orbit (500-2,000 kilometers), there are 1,500 such layers. Orbits lower than 500 kilometers will quickly bring debris back into the Earth’s atmosphere, where it will burn up. Despite this, the chances of a live satellite being hit by debris are low but increasing as the amount of debris continues to accumulate. To mitigate this risk, satellite operators are taking precautions such as equipping their satellites with the ability to move and paying people to constantly monitor the collision risk from debris.
The space debris poses a significant threat due to its high velocity. Objects as small as 1 cm (0.4 inches) can damage satellites, while larger debris (at least 100 mm or 4 inches) can destroy satellites and seriously damage the International Space Station (ISS). Despite the large number of fragments in orbit, most are relatively small and can only cause damage to smaller objects such as satellites. However, the larger pieces of debris, such as dead satellites and rocket stages, can cause significant damage to other objects in orbit.
The space debris problem is not limited to low Earth orbit, as debris can also be found in higher orbits, including geostationary orbit (GEO) and the Moon. Debris in GEO, which is located at an altitude of around 36,000 kilometers, can be particularly problematic as it is used by a large number of satellites for communication and other purposes.
There is currently no known technology that can effectively eliminate space debris, and efforts to address the issue have largely focused on preventing the creation of new debris and mitigating the risks posed by existing debris. One potential solution that has been proposed is the use of debris removal satellites, which would be tasked with capturing and removing debris from orbit. However, the development and deployment of such satellites is still in the early stages and it is unclear when they will be operational.
In conclusion, the proliferation of satellites and the accumulation of space debris in orbit pose significant hazards to both humans and their machines. While the chances of a live satellite being hit by debris are currently low, the risk is increasing as more debris accumulates in orbit.