VLEO and space sustainability: how does Very Low Earth Orbit contribute to the shift towards more sustainable space activities?

Abstract The use of Very Low Earth Orbit (VLEO) has often been cited as a possible solution to the growing problem of space debris, especially as we enter the era of mega-constellations of thousands of satellites. By definition, interaction with the residual atmosphere in VLEO induces drag which rapidly pulls debris and failed satellites from orbit, minimising any long-term impact on the debris population. As such, it provides a relatively consequence free environment, at least in terms of debris considerations, for rapid and high-risk technological innovation. There are many benefits achieved from operating satellites at lower altitudes, such as improved resolution for Earth observation and reduced latency and power requirements for communications constellations. These benefits, combined with the self-cleaning nature of VLEO and rapidly reducing launch costs, continue to drive growing use and interest in VLEO. However, the sustainable use of space also demands the consideration of other impacts of the use of low Earth orbit generally, including VLEO, on the Earth and orbital environments. These go beyond debris considerations to include light and radio pollution for optical and radio astronomy, and the carbon footprint of the space industry. Meanwhile, the impact on the atmosphere of satellites re-entering the atmosphere at end-of-life is known to have impacts on ozone depletion and the Earth’s radiative balance, the significance of which is still being assessed. One can imagine that in the future, with the drive for a circular space economy, moving end-of-life satellites to a reprocessing facility in-orbit becomes mandated; but this is realistically still a long-term goal. In the near term, what are the opportunities and benefits that VLEO can provide to space sustainability, and how do these need to develop to continue to be part of the solution in the long term? This paper reviews factors driving the growing interest in the use of VLEO, including benefits for sustainability, alongside the longer-term technology challenges that need to be addressed to ensure that VLEO remains a sustainable solution in a future circular economy for space.