It is known since the seminal study of \citet Las1989 that the inner planetary system is chaotic with respect to its orbits and even escapes are not impossible , although in time scales of billions of years .
The aim of this investigation is to locate the orbits of Venus and Earth in phase space , respectively to see how close their orbits are to chaotic motion which would lead to unstable orbits for the inner planets on much shorter time scales .
Therefore we did numerical experiments in different dynamical models with different initial conditions – on one hand the couple Venus-Earth was set close to different mean motion resonances ( MMR ) , and on the other hand Venus ’ orbital eccentricity ( or inclination ) was set to values as large as e = 0.36 ( i = 40 ^ { \circ } ) .
The couple Venus-Earth is almost exactly in the 13:8 mean motion resonance .
The stronger acting 8:5 MMR inside , and the 5:3 MMR outside the 13:8 resonance are within a small shift in the Earth ’ s semimajor axis ( only 1.5 percent ) .
Especially Mercury is strongly affected by relatively small changes in eccentricity and/or inclination of Venus in these resonances .
Even escapes for the innermost planet are possible which may happen quite rapidly .