I had missed this when they were posted, but the Chair Force Engineer had some thoughts on DIRECT a couple weeks ago, here and here.
“Wow.” Are we to believe that ESAS was designed with little or no consideration of what the supporting infrastructure would cost? It would certainly explain why we’re stuck with the unaffordable Ares I and Ares V.
I’d like to say that I’m surprised, but sadly, I’m not.
Further NASA statements such as “Ares I + Ares V uses 15 SRB segments, while two Jupiter 232’s use 16 segments” also reveal an incredibly simplistic approach to cost estimation. Such simple methods might be appropriate for pre-algebra students. Professional cost estimators ought to know better. That’s why cost estimation is so difficult; there may literally be thousands of dependent and independent variables that make up the true cost of the system over its lifetime. Saving a few million in rocket hardware may have bigger reprocussions with development dollars, standing army costs, and infrastructure costs. It’s best summed up on Slide 26, where Jupiter’s higher launch costs (measured in tens of millions per launch) are offset by the savings of billions in development costs.
We’d have to see a full life-cycle cost accounting with assumptions to know whether or not it’s a good saving to cut development cost at the price of higher ops costs. It depends on how much you’re going to fly. But I suspect that it probably is, because the up-front costs are in expensive near-term dollars whereas the flight costs are down stream and discounted, and the flight rate will probably never get big enough to justify spending more on development to reduce marginal cost per flight. That’s always the problem with expendables.
I really need to write up my talk on marginal costs from Space Access.