That's Because You Are Using A Limited Definition Of Cats
Optimizing launcher configuration is hardly a technically advanced way to achieve CATS. That is not what I am talking about. I'm talking about air breathing rocket engines, laser propulsion, nuclear technology, magnetic launch, space elevators and or any other feasible lower cost option to current expensive chemical rockets. We don't need to lower the cost by half we need it lowered by an order of magnitude preferably 2. The Way to Go in Space is a somewhat dated review of the possibilities from a 1999 issue of Sciam. Of course I may have to slide towards Tom's low view of the accuracy of Sciam since it treats Roton as a serious possibility ;-).
regards,
Mark