Hi Ken -

The architecture you're describing is similar to the SEI architecture of Bush Snr, and its simply too expensive to use. The functional blocks I lifted from Valentin Glushko's designs are about the cheapest way to split up useful manned Moon flight.

I don't anticipate Earth to LEO costs coming down any time real soon - first, it is rocket science, in other words high enigineering costs manufactured to exacting specifications, and second, and more importantly, the energy costs are really high with current propulsion technologies. Maybe something like Chan Diaz's engines might lower this, but that's a long way off. Realistically, nothing else is around that I can see, and I am open.

For manned Mars, what is needed are a variant of Aldrin's cyclers using solar thermal propulsion.
In any case, back ontamination is going to have be definitively shown not to be a problem before manned Mars flight is going to be alllowed.

As far as asteroids and comets are concerned, before the collapse of the Energia storage sheds a really cheap manned trip to Phobos and Deimos was possible, but that is no longer an option.

Bush Jnr plan is the only viable option, and only if it is tied into Dr. Mazanek's CAPS planetary defense system.

ep