Space debris is emerging as a problem with the potential to cause major socio-economic impacts. It is currently estimated that there are over 900,000 pieces of debris greater than 1 cm in size orbiting the Earth.

Collisions with such objects can damage and even destroy satellites, leading to concerns over the sustainability of future space activities and even the safety of human spaceflight.

As well as reducing the number of debris objects in low Earth orbit (LEO), we must improve the accuracy in predictions of near misses and to enable timely and efficient planning of collision avoidance manoeuvres. A major challenge is that current orbit modelling and prediction are insufficiently accurate because of the variable drag effect of the upper atmosphere on satellites. The dominant unknown in orbital trajectory predictions of LEO objects is the density of the region of the upper atmosphere known as the thermosphere. Given that the thermospheric density can vary by 80% every day and by 250% during a solar storm this is a major modelling challenge.

Lancaster University researchers have been working to better predict orbital conjunctions (collisions) using a fully coupled model of the lower and upper atmosphere that ingests a broad range of measurement data using novel mathematical techniques. This goal is to provide a complete and accurate picture of the ionosphere and thermosphere that will facilitate a step-change in the UK Met Office's ability to specify and forecast thermospheric density.