Thermal thrust acting on LAGEOS due to direct solar radiation

The study of the LAGEOS orbital features has concentrated on the modeling of nongravitational effects acting on the satellite. LAGEOS tracking data analysis shows that the residuals on the along-track acceleration have a secular drag of about -3.4 x 10-12 m/s2 and signatures whose periods arise from linear combinations of the longitude of the LAGEOS node and of the sun. Thermal thrust due to the earths infrared radiation (Rubincam effect) and charge and neutral particle drag seem to explain the overall secular drag. The Yarkovsky-Schach effect due to solar heating is a probable mechanism to explain the signatures occurring, together with the earth and LAGEOS anisotropic optical properties. The new Yarkovsky-Schach model corrects some inaccuracies of the old one, and studies possible improvements not yet considered.