var electrons = document.querySelectorAll('.electron'),
    paths = document.querySelectorAll('.path'),
    startDuration = 2;
for(var i = 0; i < electrons.length; i++) {
  var myDelay = -(i * 0.5);
  orbit(electrons[i], paths[i], myDelay);
}
function orbit(electron, path, delay) {
  TweenLite.to(electron, startDuration, {rotationY:'-360', ease:Linear.easeNone,
               onComplete: orbit(electron, path, delay)}, delay);
  TweenLite.to(path, startDuration, {rotationZ:'360', ease:Linear.easeNone},
               delay);
}

TweenLite.to(electron, startDuration, {
        rotationY:'-360',
        ease:Linear.easeNone,
        onComplete: function(){
            orbit(electron, path, delay);
        }
    },delay);