Over the past few years, humanity has launched so many satellites into space that the problem of debris in orbit has become much worse. Currently, there are more than 6,600 tons of space debris in low Earth orbit (160 to 2,000 km), according to an annual report from the European Space Agency (ESA).
Image source: esa.int
That’s more than the 6,000 tonnes NASA estimated were in orbit in 2023. The problem is largely invisible, but massive, because “we depend on satellites as a source of information in our daily lives, from navigation to telecommunications, services and Earth observation, including defence and security,” said ESA Director General Josef Aschbacher.
Space debris comes from a variety of sources. Sometimes a payload, such as a working satellite or calibration instrument, explodes or collides with another object in orbit. There are objects that are deliberately jettisoned during the course of a payload’s operations, such as instrument covers or tools used by people in orbit. And there are pieces of debris that result from accidents, such as collisions, explosions, or wear and tear on spacecraft.
Even tiny pieces of space debris just a millimetre in size can cause serious damage to satellites and other spacecraft. A piece of debris just a centimetre in size has the energy of a hand grenade. There are currently at least 1.2 million pieces of space debris larger than 1 cm in orbit – each of which can collide with another object and produce hundreds of new fragments in a chain reaction known as the “Kessler effect”. According to ESA’s MASTER modelling programme, at an altitude of about 550 km there is as much debris as there are active satellites.
Since the beginning of the space era, both the number of objects in orbit and their combined mass and area have been growing, increasing the likelihood of unintentional collisions of operational spacecraft with space debris. An additional contribution is made by the miniaturization of satellites and their growth. In 2024 alone, several major and minor incidents occurred, resulting in more than 3,000 new trackable objects in orbit.
There are no international space regulations governing the cleanup of low Earth orbit debris. Therefore, some national space agencies are developing their own guidelines, including:
- Preventing the release of mission-related objects such as lens caps and deployment mechanisms;
- Use of materials and components that minimize the risk of destruction of objects during and after the completion of missions;
- Implementation of reliable mechanisms for deploying devices that do not leave behind waste;
- Designing structures with minimal risk of failure due to internal energy sources;
- Integration of the possibility of disposal of the device at the end of its service life already at the design stage;
- Creation of passivation systems to neutralize energy sources, including batteries and fuel, at the end of the mission;
- Development of designs that are capable of burning completely upon entry into the atmosphere.
In 2028, the ClearSpace-1 space debris removal device is scheduled to remove the PROBA-1 satellite from orbit. The 112-kg device was developed by the Swiss company ClearSpace and captures objects using four “claws”. Tokyo-based Astroscale also offers space debris removal services. Both companies have agreements with the UK Space Agency to remove several retired British satellites from orbit.