A Systems Perspective on Satellite Proliferation

The number of satellites being placed into orbit now is increasing dramatically, particularly with large constellations of small commercial satellites in low Earth orbit.  A prime example is Space X’s constellation of Starlink satellites, designed to provide global satellite Internet access and mobile phone service.  As of February 2023, there are over 3,580 Starlink satellites in orbit.  Nearly 12,000 Starlink satellites are planned to be deployed to complete the first phase of the system, with a possible extension later to a total of 42,000 satellites.  The effort is made economically feasible by high-volume mass production of the satellites and Space X’s development of the Falcon 9 reusable rocket booster that dramatically reduces launch costs.

The U.S. regulatory approval for the Starlink constellation and its spectrum allocation was given by the Federal Communications Commission (FCC) in November 2018.  This approval was paralleled by approval by the International Telecommunications Union (ITU).  Both of these bodies are primarily focused on regulating the use of the electromagnetic spectrum for communications.

In addition to commercial use, the Starlink system has various military users.  Recently it has been revealed that Ukrainian units have been employing Starlink to control commercially-produced drones to attack Russian forces in the war in Ukraine.

Separate from the management of the spectrum, there appears to be little control at the international level for managing the physical space of low earth orbit.  New large constellations such as Starlink add to an already heavily congested space environment.  FCC approval of the Starlink constellation was contingent upon Space X assuring that they would implement an operations protocol to de-orbit Starlink satellites at the end of their lives.  This would be done by having the satellites propel themselves to a disposal orbit where they will re-enter the atmosphere approximately one year after the completion of their mission.

Space X says that Starlink satellites are designed to autonomously avoid collisions, both with each other and with other satellites, using uplinked satellite tracking data.  A concern I have is the reliability of this mechanism, particularly if Starlink satellites suffer system failures that would prevent them from deorbiting.  As is now well demonstrated, satellite collisions create large amounts of space debris that in turn can greatly increase the incidence of further collisions.  The process can result in a runaway amplifying feedback effect, where collisions cascade.  This could quickly make a particular orbital regime too dangerous to use.  The process has been termed the Kessler Syndrome, named after the scientist who first described it in detail in 1978.  In my view, having such a large number of satellites in low earth orbit in a small altitude band seems rather hazardous.  It could make manned spaceflight too hazardous to conduct for many decades and greatly impair other uses of near Earth space.

In addition to the prospect of orbital collisions, astronomers are distressed by the increasing effects very large constellations of satellites will have on ground-based optical astronomy.  Solar reflections off the Starlink satellites are already creating bright tracks in the telescope images, greatly decreasing the scientific value of the observations.  As the number of satellites increases, the problem will only grow.  Space X has attempted to reduce the reflective brightness of the satellites, but only so much can be done to darken components such as the satellite solar cell arrays.

The commercial benefits of satellite systems such as Starlink need to be weighed against possible systemic risks and harm to the interests of other communities, such as optical astronomy science and other users of low Earth orbit.  I feel that better international management of what is allowed to be placed into the space environment is an urgent requirement, as this is a matter that affects the whole population, not just those who directly benefit from the systems.

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