OK Larry I know tou have mentioned many other things that ned to be developed although I and others disagree with the closed loop life support requirement. You don't even need that for a colony on Mars when you can use local CO2 and Water as resources. However, I thought the primary expense was the launcher and I thought your earlier comments implied something similar so lets pin down some particulars. How much do you think a heavy lift derived from the shuttle will cost?

Do you also think NASA's 50 billion for a more complex plan was bogus? It requires more equipment and launches. 20 billion seemed low to me initially without any expertise in the area until I saw NASA come in with a figure about twice as high for a mission which seemed to me should cost about twice as much. They planned to send 50 % more people with a larger number of vehicles requiring more launches and using more space (and hence mass) per astronaut.

You also have to look at Apollo as a groundup program costing 70 billion in today's dollars. It covered a lot of technology development we don't need this time. Unless the ISS is a total waste we should also have learned a lot needed to design the habs. Just as a heavy lift is no longer a ground up program the hab isn't either. I have a real hard time seeing why a mission to Mars should cost much more than half of Apollo's cost using a simple Mars Direct program when we have so much more computer power and design software than we had back then. 20 billion may be low, but I don't know enough to say that. It seems to me by comparison of the complexity of Mars Direct and current knowledge with both Apollo and NASA's Mars reference mission that a Mars Direct program should cost between 20 and 35 billion.

This is a very rough ball park approach, but I don't see much evidence that you are doing anything much more detailed. You throw out a laundry list of things to do but don't compare those to past costs, assess how much further we are ahead in starting on new versions than we were on the olds ones, or address much the behind the scenes work that has already been done (shuttle C, Magnum, transhab, space suits esc).

Regards,
Mark