How Far Can the Number of Artificial Moons in Low Earth Orbit Be Increased?

Abstract

The number of artificial moons is increasing exponentially. While a few years ago only a few thousand active satellites and roughly 20,000 traceable pieces of debris orbited the Earth, today only the Starlink system has approximately 4,000 members, which may increase tenfold in the next few years. In addition, in the daily press you could also read about the plans of a constellation of 300,000 members.
The question arises, is there room in low Earth orbit for so many satellites? We can examine the question from several angles. If the satellites orbit too close to each other, they can interfere with each other’s operation and communication. On the other hand, due to the deviation of the Earth’s gravitational field from being spherically symmetric, perturbations caused by the celestial bodies of the Solar System and non-conservative forces, near-collision conditions may occur from time to time. In the following, we give an upper estimate of how many artificial moons fit in low Earth orbit by numerically examining the effect of gravitational perturbations.