FLASHBACK: NASA does not deny the “over $2 billion” cost of a single SLS launch.

The White House number appears to include both the “marginal” cost of building a single SLS rocket as well as the “fixed” costs of maintaining a standing army of thousands of employees and hundreds of suppliers across the country. Building a second SLS rocket each year would make the per-unit cost “significantly less,” Hambleton said.

What the White House cost estimate did not include, however, was development costs. Since 2011, Congress has appropriated approximately $2 billion per year for the “development” of the SLS rocket (this does not include hundreds of millions of dollars spent annually on ground systems “development” for the rocket at Kennedy Space Center). If these costs are amortized over 10 launches of the SLS vehicle during the 2020, the per-flight cost would be approximately $4 billion per flight.

And that still doesn’t include the payload.