Space is crowded. There is a traffic jam in low earth orbit (LEO, 200 to 2000 km above the earth). There are a very large number of both civilian and military satellites in LEO, both operational and defunct – not to mention the innumerable pieces of random space debris including spent rocket parts, pieces of equipment accidentally lost by astronauts, and very small flecks of paint chips and other debris too small to track. NASA estimates that there are around 27,000 pieces of space debris, 10 cm or larger, in LEO. But the real number is much higher since anything smaller than 5 cm is not tracked … and all of it travelling at speeds between 10 and 15 Km per second, which could cause significant damage if they hit a functioning satellite.
Civilian satellites in LEO are used for such things as weather monitoring, agricultural forecasting, urban planning, climate change assessment, and all forms of communications including facilitating electronic financial transactions, money transfers, air traffic control, emergency preparedness, and search and rescue. In short, our modern technological life would be impossible without LEO. The military uses of space include earth observation (“spy satellites”) and battlefield communications. Critically, no states’ military has (yet) placed weapons in space. Military satellites (for now) are used to support terrestrial military operations, not conduct them. Intermingled among the operational civilian and military satellites in LEO are defunct satellites that are no longer functioning.
NASA estimates that 99% of the mass of all space debris is in the form of no-longer-in-use satellites. NASA scientist Donald Kessler has calculated that the volume of space debris in LEO could be so dense that satellites would soon be crashing into each other creating more debris which, in turn, would crash into other satellites creating even more debris. This cascading effect of increasing debris creation, or the “Kessler Effect”, could result in LEO being unusable due to the threat of damage to satellites. By some estimates, the congestion in LEO today is very close to reaching the threshold for the “Kessler Effect” to become a reality.
The world’s space fairing nations face two significant challenges to maintain the sustainable use of LEO. First, they must ensure that the number of satellites in LEO is manageable so that the number and mass of debris does not increase in a way that would trigger a Kessler Effect. Second, their militaries need to address the threat their adversaries’ military satellites represent, without destroying them and causing new debris in LEO, thereby increasing the chances of a Kessler cascade and threatening civilian satellites.
Despite best efforts, challenges remain. How can space fairing nations (1) ensure the sustainable use of LEO while avoiding the Kessler Effect; and how can they (2) address the threat posed by adversaries’ military satellites without destroying them, to avoid creating even more debris?
Clearly then, some form of international cooperation is needed to ensure the continued sustainable use of LEO. In 2008 the EU proposed a voluntary International Code of Conduct on the Peaceful Use of Outer Space. However, mistrust among the main space fairing countries (i.e., USA, Russia, and China) bogged down negotiations on the Code which ended in failure in 2014. Russia and China, for their part, also in 2008, proposed at the UN Committee on Disarmament (CD) a legally binding treaty to prohibit the placement of weapons in outer space. However, the long-standing disfunction of the CD and the distrust of Western countries as to Russia and China’s true intentions in the field of disarmament has made this draft treaty a non-starter.
Despite best efforts, challenges remain. How can space fairing nations (1) ensure the sustainable use of LEO while avoiding the Kessler Effect; and how can they (2) address the threat posed by adversaries’ military satellites without destroying them, to avoid creating even more debris? For now, there is an uneasy equilibrium that seeks (1) to find ways to remove defunct satellites from LEO; and (2) either tolerate adversaries’ military satellites or find ways to inhibit their ability to spy on your military without actually destroying them.
This uneasy equilibrium exists among state actors in space. However, since 2015 a new challenge has emerged – non-state actors in space. Private sector companies have been launching satellites for a long time (e.g. Canada’s Telsat satellite by MDA). In recent years, however, there has been a proliferation of private sector companies providing space-based communications and earth observation services, much of which can be used for military purposes. A prominent one is Space X’s Starlink network of communications satellites. Since 2018, Starlink has put more than 5,000 satellites in LEO, and more are on the way. While these satellites are relatively small (roughly the size of a table and weighing around 260 kg or 560 lbs) compared with more traditional communications satellites, they are also more material in LEO. While private and civilian in nature, Starlink has been used by the Ukrainian military in their resistance of the Russian invasion. So, although Starlink is a private enterprise, Russia could regard it as a military threat.
Similarly, there has been a proliferation of private sector earth observation satellites being used to monitor developments on the ground in the Ukraine conflict. Images from these privately owned satellites are being shared on the internet, including on Twitter/X, to inform open-source intelligence efforts (OSINT). Now even private individuals can access intelligence imaging of developments on the ground in Ukraine including defence preparations and military deployments. While the quality of these privately sourced satellite images is nowhere near as detailed as those of state intelligence agencies, nonetheless, militarily sensitive images, and the expert interpretation to explain them, are now freely available to anyone who wants them, thanks to private sector satellites in LEO.
The military challenges represented by satellites in LEO are therefore no longer confined to those of adversary states. The images and OSINT made possible by private sector satellites also represent a real threat to a states’ military. This adds a new layer of complexity to dealing with potential military threats from LEO without causing a Kessler Effect catastrophe. Ensuring the sustainability of space should therefore no longer be only a state responsibility but must include non-state actors in any future measures.