Night lights from space: potential of SDGSAT-1 for ecological applications

Light pollution affects biodiversity at all levels, from genes to ecosystems, and improved monitoring and research is needed to better assess its various ecological impacts. Here, we review the current contribution of night-time satellites to ecological applications and elaborate on the potential value of the Glimmer sensor onboard the Chinese Sustainable Development Goals Science Satellite 1 (SDGSAT-1), a novel medium-resolution and multispectral sensor, for quantifying artificial light at night (ALAN). Due to their coarse spatial, spectral or temporal resolution, most of the currently used space-borne sensors are limited in their contribution to assessments of light pollution at multiple scales and of the ecological and conservation-relevant effects of ALAN. SDGSAT-1 now offers new opportunities to map the variability in light intensity and spectra at finer spatial resolution, providing the means to disentangle and characterize different sources of ALAN, and to relate ALAN to local environmental parameters, in situ measurements and surveys. Monitoring direct light emissions at 10–40 m spatial resolution enables scientists to better understand the origins and impacts of light pollution on sensitive species and ecosystems, and assists practitioners in implementing local conservation measures. We demonstrate some key ecological applications of SDGSAT-1, such as quantifying the exposure of protected areas to light pollution, assessing wildlife corridors and dark refuges in urban areas, and modelling the visibility of light sources to animals. We conclude that SDGSAT-1, and possibly similar future satellite missions, will significantly advance ecological light pollution research to better understand the environmental impacts of light pollution and to devise strategies to mitigate them.