Predicting where falling space debris will end up

What is it about?

Imagine a graveyard hurtling through space at 27,400 kilometres per hour. Every headstone represents a silent, tumbling satellite. These defunct machines in Low Earth Orbit are not stationary; they are gradually pulled down by the Earth's upper atmosphere, which is very thin. It is notoriously difficult to predict exactly when they will drop. This unpredictability makes it challenging for mission planners to avoid collisions or prepare for fiery re-entries. However, we have now developed a way to improve these predictions by looking backwards. By comparing the known past paths of six specific pieces of debris with standard physics models, our team has created a custom calibration factor. This factor acts like a corrective lens, adjusting the calculations to account for each object's unique interaction with the air. The team tested this method over a six-month period and found that their simulations closely matched reality. In some cases, the prediction was off by only 20 metres after six months of orbiting. This breakthrough enables operators to manage the growing cloud of space debris more effectively, eliminating the need for expensive new sensors. Understanding how the air affects our past can help us to navigate the future of our crowded sky more safely.

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Photo by NASA on Unsplash

Photo by NASA on Unsplash

Why is it important?

This study shows that we can accurately predict the path of uncontrolled space debris by calibrating models against their flight history. This level of precision is crucial for preventing collisions in our increasingly crowded orbital lanes and for planning the safe lifetime of satellites. The method was only tested on six objects; its accuracy over, for example, longer timescales and during extreme solar storms, remains an open question.

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