Why do trojan ASCs (not) escape?

The orbits of 12 Trojan asteroids, which have Lyapunov times T-L similar to 10(5) years and were previously classified as ASCs(=asteroids in stable ch aos), are integrated for 50 Myrs, along with a group of neighbouring initia l conditions for each nominal orbit. About 40% of the orbits present strong instabilities in the inclination, which may be attributed primarily to the action of the (v)16 secular resonance; two escapes are also recorded. High er-order secular resonances, involving the nodes of the outer planets, are also found to be responsible for chaotic motion. Orbital stability depends critically on the choice of initial conditions and, thus, these objects can be regarded as being on the edge of strong chaos.