Scientists at the ORB study the state of Cassini Mercury. They have shown that the obliquity of Mercury is close to zero, i.e. that its rotation axis is almost perpendicular to the orbital plane Mercury around the Sun. This value is very important for the Peale experiment. They do this work on the long-term evolution of orbital elements of Mercury, its precession and plan Laplace. For more information: Rambaux and Bois (2004) (2004), Yseboodt and Margot (2006) (2006), and Peale, Yseboodt, and Margot (2007) (2007).