Impact of the Atmospheric Drag on Starlette, Stella, Ajisai, and Lares Orbits

The high-quality satellite orbits of geodetic satellites, which are determined using Satellite Laser Ranging (SLR) observations, play a crucial role in providing, e.g., low-degree coefficients of the Earth's gravity field including geocenter coordinates, Earth rotation parameters, as well as the SLR station coordinates. The appropriate modeling of non-gravitational forces is essential for the orbit determination of artificial Earth satellites. The atmospheric drag is a dominating perturbing force for satellites at low altitudes up to about 700-1000 km. This article addresses the impact of the atmospheric drag on mean semi-major axes and orbital eccentricities of geodetic spherical satellites: Starlette, Stella, AJISAI, and LARES. Atmospheric drag causes the semi-major axis decays amounting to about ▲a = -1.2, -.12, -.14, and -.30 m/year for LARES, AJISAI, Starlette, and Stella, respectively. The density of the upper atmosphere strongly depends on the solar and geomagnetic activity. The atmospheric drag affects the along-track orbit component to the largest extent, and the out-of-plane to a small extent, whereas the radial component is almost unaffected by the atmospheric drag.