var target : Transform;
var speed=1.0;
var rotateSpeed = 1.0;
function FixedUpdate ()
{
    var directionRotate = target.position - transform.position;
    transform.rotation = Quaternion.Slerp (transform.rotation, Quaternion.LookRotation(directionRotate), rotateSpeed * Time.deltaTime);
    transform.eulerAngles = Vector3(0, transform.eulerAngles.y, 0);
    transform.Translate(0,0,speed * Time.deltaTime);
}