  A number of irregular moons of the Jovian planets have recently been
discovered. Most adequate way of their origin is capture, but detailed
mechanism is unknown. A few possibilities are discussed: collisions, gas drag,
tidal destruction of a binary asteroid. In this paper the capture process in
restricted four body problem (RFBP) is researched. The interaction with regular
satellite can be studied by this way as well as binary asteroid destruction in
Hill sphere of planet. The energetic criteria of ballistic capture are studied
and some numerical experiments are developed. It is confirmed, that capture in
four body problem is more probable on retrograde than on prograde orbit. In
according with our results, encounter with regular satellites is more effective
mechanism to create an irregular satellite population, than a binary asteroid
flyby.
