5:15 PM - 7:15 PM
[PEM14-P15] Study of thermospheric density from orbit variation of STARLINK satellites
Keywords:Thermosphere, Atmospheric dencisy, Satellite orbit change, STARLINK
The Earth's atmosphere gradually transitions into the solar-terrestrial system at 100-1000 km altitudes. Part of the atmosphere is ionized by ultraviolet and X-ray radiation from the Sun, resulting in weakly ionized plasma, called the ionosphere. However, the degree of ionization is only 0.1 percent at most. Most of the extremely thin atmosphere is electrically neutral, called the thermosphere. Difficulties in the study of the thermosphere and the ionosphere are often due to a lack of knowledge about atmospheric density. There is a need to develop a monitoring system for the atmospheric density in the thermosphere. This altitude region is also a space where satellites fly. With the recent progress in space development, the number of satellite launches has drastically increased in recent years, and there are concerns about collisions between satellites and between satellites and debris. The situation also increases the demand for accurate atmospheric density information. This research aims to develop a method for estimating the atmospheric density from changes in satellite orbits. Although this method is not new, we want to shed light on the recent situation of many satellites flying. We focus on the STARLINK satellites the US company SpaceX launched (more than 6000!) for internet communication. Their orbitals are nearly circular at 200 to 600 km altitudes with inclination of around 50 degrees. Public orbit data from the website are updated 1 to 4 times daily for each satellite, realizing the big-data analysis. Most STARLINK satellites are operated to keep the constant altitudes, but some are in free fall. We have already found that atmospheric density increases during geomagnetic storms. In the presentation, we will discuss the development of our atmospheric density estimation method.