Page:The Case for Space Environmentalism.pdf/3

 ''Fig.1 The growth of all tracked objects in space over time. Updated version of the plot from [3]. Data extracted from the General Catalog of Artificial Space Objects [5].''

Historically, telecommunications satellites were typically placed into GSO. The new satellite constellations, however, are at LEO — partly to minimise the latency (signal delay time), but also to reduce the cost to launch, and ensure rapid decay of failed satellites. Because LEO satellites can access only a small portion of the Earth, many more satellites are needed to achieve the equivalent GSO global coverage. The impact of such large constellations has caused considerable disquiet and much work in the astronomical community to mitigate the deleterious effects [3,6,7,8,9,10].

Of the many thousands of satellites that have been launched over the years, most have reentered, exploded, or continue to orbit the Earth as derelicts, along with other leftover rocket parts. (See Fig. 1.) At LEO a realistic lifespan is about five years, so constellation operators will continuously need to replace satellites. This will require frequent launches and deliberate de-orbiting, leading to a constant turnover within LEO, and the risk of more derelicts from failed satellites. Various processes have led over the years to an ASO population of small pieces of space debris. Down to a size of roughly 10 cm, these can be tracked with telescopes or radar on Earth; there are 22,436 such pieces in The General Catalog of Artificial Space Objects [5].

In Fig. 2 we illustrate the distribution in height and spatial distribution of the entire tracked ASO population, divided into categories. In Fig. 3 we show a distribution of a subset of the tracked ASO population in angular momentum space. These two visualisations make the