Enhancing Orbit Determination Through Atmospheric Modelling

Satellites interact with the atmosphere as they orbit the Earth.

This interaction changes the orbit, slowing the satellites down ever so slightly until they eventually de-orbit and burn up in the atmosphere.

The International Space Station loses 100 m of altitude every day and needs to boost its orbit periodically.

If you want to predict the orbit of a space object you need to take a lot of things into account; the variable gravity well over mountains and oceans, the size and shape of the satellite, the light from the sun, the sunlight reflected from the Earth, whether you are in the sun or in the shadow of the Earth, and the density and charge of the changing atmosphere.

It is a non-trivial problem.

SERC researchers in Research Program 2 tackled the atmosphere component in orbit determination and developed a refined atmospheric mass density (AMD) model to give more reliable orbit predictions.

SERC Program 2 researchers...developed a refined atmospheric mass density model to give more reliable orbit predictions. 

The new AMD model includes models for both neutral and ion densities in low Earth orbit atmosphere.

The ion (predominantly oxygen ions) density and dynamics have been included in the drag equations.

Above altitudes of 500 km the ion contribution to the overall AMD becomes significant, and at heights of 1,000 km can be as much as 30% of the today mass density.