Long-Term Evolution of the Space Environment Considering Constellation Launches and Debris Disposal

Increasingly frequent launch activities, as well as the development of mega constellations, would cause a drastic increase in the number of space objects, which will then alter the evolution of outer space. To reveal this long-term change, an accurate space-environment model is required. There are two main approaches to building this model, one of which is to track the state of space objects individually, which will use significant computing resources; and the other is to take macroscopic variables, such as spatial density, as the state variable to depict a group of space debris, which requires less computational effort. In this article, a space debris environment evolution model with spatial density as the state variable is established, which considers the nonzero eccentricity of the debris orbit and utilizes the NASA breakup model to ensure accuracy. In addition, the Gaussian mixture model is applied to take the uncertainty of launch activities into account. The long-term impacts of mega constellations and their postmission disposal (PMD) on the debris environment are discussed based on the evolution model. It was found that constellations with high orbit altitude, such as OneWeb, will lead to an exponential increase in space objects in low Earth orbit. In addition, deorbit time is the main factor affecting the PMD efficiency, followed by deorbit strategies.