> Yeah but you see, they will miss that 'one mission per year' thing by quite a large margin.

So, that's fair. But it's also complicated. Part of that number (for EGS) is for the upkeep of buildings like the VAB. Which is fair - SLS is the only real user, so they get charged for it.

But it's also kind of not fair, since NASA's going to keep it around, even if SLS wasn't a thing. As evidenced by NASA doing just that in the interim period between Constellation and SLS.

> And I don't think just excluding all 'prior development' as if it was irrelevant makes much sense. Development cost should be considered as part of a program.

I completely agree with you in general.

But I think that it's easier to tally the development costs separately.

And it's important to know how much it costs to just build and launch the rocket. A number which NASA (outside of OIG) has been extremely reluctant to release to the public. As far as I know, NASA leadership has never made specific claims about how much SLS costs, just that the OIG numbers are wrong and/or misleading.

Once the program ends, we'll have a better idea of how to amortize the develop costs over the total number of launches.