Kyoto, Japan -- The space around Earth is becoming increasingly crowded, with thousands of satellites and pieces of debris now sharing low Earth orbit. Even above this region -- at altitudes of several hundred kilometers -- the extremely thin upper atmosphere can slow satellites down, making accurate information on atmospheric density essential for predicting satellite motion and preventing collisions.

The upper atmosphere is composed of more than 99 percent electrically neutral atmosphere called the thermosphere, and thermospheric density is the term used to describe neutral atmospheric density at heights from 100 to 1000 kilometers above the Earth's surface. While the ionized gas of the ionosphere makes up less than 1 percent of the atmosphere, the effect of the ionized gas on radio wave propagation renders the ionosphere relatively easy to observe, while thermospheric observations pose a considerable challenge.

Nonetheless, developing observation methods for thermospheric density is essential both to further advancing the science of the upper atmosphere and for applications in space engineering. These needs inspired a team of researchers at Kyoto University to develop a new method of visualizing this elusive environment.