Page:The Case for Space Environmentalism.pdf/7

 as a Carbon Footprint analogue, that should be loosely interpreted as the burden that any ASO poses on the safety and sustainability of any other ASO and the environment itself. In order to illustrate potential damage, throughout this article we frequently use a simplified and standardised potential 2030-era population of 100,000 objects at an altitude of 600 km. A full environmental assessment would of course use a much more sophisticated approach.

In considering the impact of satellites on astronomical observations, we have to bear in mind that individual sources of light pollution may be billions or even trillions of times brighter than those that astronomers study, and that many of the most scientifically important observations concern unrepeatable time sensitive or transient events — such as the detection of Near Earth Objects, Supernovae, or Fast Radio Bursts.

Optical astronomy

ASOs can be seen from Earth because they reflect sunlight. Their brightness depends on numerous factors, such as the size of the satellite, its reflective properties, its height above the Earth and its orientation. As satellites move across the field of view of an astronomical exposure they leave streaks across the image (Fig. 4). For damage already caused by satellites in 2021, see [6,7,8,17] and references therein. To see the likely impact very soon, consider our simplified 2030-era LEO satellite population of 100,000 satellites at a height of 600 km.



''Fig. 4. An image of the sky taken by the Dark Energy Survey Camera in 2019. Although at that point there were relatively few Starlink satellites, the effect is severe because many''