[nordsieck]

> SLS cost way, way more then $1 billion per launch. More like 4 billion $ per launch.

So, the full stack of SLS costs $4.1B. But that includes the cost of Orion which is ~$1.3B when you include the European Service Module, and it includes the cost of 1 year's worth of ground support equipment including upkeep for various buildings like the VAB, etc.

The marginal cost of a cargo SLS (should one ever launch, which is looking increasingly unlikely) is a bit over $2B. Which is still a horrifically high price.

For people who don't know much about SLS, one way to put its cost into context is, every time the full stack with Orion launches, that's about 1/6th of NASA's yearly budget. And that doesn't count any development cost which is several tens of Billions.

[panick21_]

I'm not sure that's true. I would bet with Orion its even more. It depends what you consider to be work before launch 1 as launch cost. And we don't really yet know the cost of the EUS.

You can of course get higher if you add development cost as well. But that depends on how many launches there are.

[nordsieck]

> I'm not sure that's true.

From the OIG report[1]:

> We project the cost to fly a single SLS/Orion system through at least Artemis IV to be $4.1 billion per launch at a cadence of approximately one mission per year.47 Building and launching one Orion capsule costs approximately $1 billion, with an additional $300 million for the Service Module supplied by the ESA through a barter agreement in exchange for ESA’s responsibility for ISS common system operating costs, transportation costs to the ISS, and other ISS supporting services. In addition, we estimate the single-use SLS will cost $2.2 billion to produce, including two rocket stages, two solid rocket boosters, four RS-25 engines, and two stage adapters. Ground systems located at Kennedy where the launches will take place—the Vehicle Assembly Building, Crawler-Transporter, Mobile Launcher 1, Launch Pad, and Launch Control Center—are estimated to cost $568 million per year due to the large support structure that must be maintained. The $4.1 billion total cost represents production of the rocket and the operations needed to launch the SLS/Orion system including materials, labor, facilities, and overhead, but does not include any money spent either on prior development of the system or for next-generation technologies such as the SLS’s Exploration Upper Stage, Orion’s docking system, or Mobile Launcher 2.

> And we don't really yet know the cost of the EUS.

We have an idea of an initial cost estimate from this[2].

NASA agreed to buy 2 core stages and 2 EUSes for $3.2B. Since RS-25s are around $100M each and the SRBs are around $200M each, this pushes the cost of the rocket up to $2.4B, maybe a bit more.

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1. https://oig.nasa.gov/wp-content/uploads/2024/02/IG-22-003.pd...

2. https://www.nasa.gov/humans-in-space/nasa-commits-to-future-...

[panick21_]

> We project the cost to fly a single SLS/Orion system through at least Artemis IV to be $4.1 billion per launch at a cadence of approximately one mission per year.

Yeah but you see, they will miss that 'one mission per year' thing by quite a large margin. And it will be more expensive because of that alone.

There are other traps in these numbers. OIG numbers are far better then NASA but I bet in 20-30 years when somebody does the total cost it will be higher.

> prior development of the system or for next-generation technologies such as the SLS’s Exploration Upper Stage, Orion’s docking system, or Mobile Launcher 2.

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.

[nordsieck]

> 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.