A15 Gravitation, Références, Astronomie, Métrologie
Study of the Yarkovsky diurnal effect on planetary satellites: Application to the satellites of Mars
The Yarkovsky effect is a result of a force acting on a rotating body in space caused by the anisotropic emission of thermal photons (basically re-emitted from the Sun) , which carries momentum. It is usually considered in relation to meteoroids or small asteroids (about 10 cm to 10 km in diameter), as well as artificial satellites of the Earth, since its influence is most significant for objects in this size range and not too far from the Sun. The induced force affects the orbital motion of these bodies. To our knowledge the effect on small planetary satellites has never been studied.
Here we study the perturbation caused by the Yarkovsky diurnal effect on the long term evolution of Phobos' and Deimos' orbits. In particular, the past evolution of the Mars satellites is still not completely understood. While tidal effects may have played the most important role in the past evolution of their orbits, it is still important to verify that all relevant perturbations required to compute accurately the moon orbits have been considered.
We consider the Mars system composed of a main central body (the Sun), Mars and one of its satellites. We develop a general analytical formulation describing the effect of the Yarkovsky diurnal perturbation on the variations of the semi-major axis, eccentricity. We conclude, that the Yarkovsky diurnal effect has provided only a very limited effect on the past evolution of the Mars moons. Our formulation can be easily applied to any other planetary or asteroid system.