A systematic literature review of the environmental impacts of space activities: planetary boundaries for the New Space age

Abstract

Meeting the 1.5oC global warming goal of the Paris Agreement is becoming tenuous and six of the nine planetary boundaries, a framework outlining safe limits of anthropogenic pressure on the environment, have been transgressed. A seventh will likely being crossed in the coming years. The meteoric rise of the commercial space sector, dubbed New Space, is adding fuel to the fire and is forecast to continue to grow into a $1.8T USD industry by 2035. This poses significant environmental risk to the upper atmosphere and Earth’s orbits as space activities are the only direct source of pollution in these areas. Operating with limited environmental oversight, there is a tragedy of the commons unfolding which some researchers have called an uncontrolled geoengineering experiment. To understand the scope and scale of the environmental impacts of the New Space economy, an iterative systematic literature review following the ROSES protocol was undertaken. Assessing 4254 papers published over 60 years it was established that there are environmental impacts which can be assessed using the planetary boundaries framework. Specifically, the boundaries most at risk from New Space activity are climate change, stratospheric ozone depletion, and atmospheric aerosol loading. Using the planetary boundaries framework, the orbital environment was also considered due to its increasing congestion. 252 papers were given critical appraisal and 21 were included in a qualitative synthesis of the impacts against each discussed boundary, Earth’s orbits, and the regulatory environment governing space activities. The findings of this review indicate that space technology has progressed much faster than research into its environmental impacts. Indeed, knowledge of these impacts has declined over time as the nature and intensity of activity has evolved. The emissions from rocket launches and object re-entry into the atmosphere may have more of an impact than previously thought and the orbital environment is becoming dangerously crowded due to mega-constellations. Crucially, the planetary boundaries which are furthest from transgression, stratospheric ozone depletion and atmospheric aerosol loading, are under threat from New Space activity. International collaboration between industry and governments will be required. Regulatory overhaul and further research into the environmental and socio-cultural impacts of New Space activity is urgently needed.