WELL, YES: NASA should consider commercial alternatives to SLS, inspector general says.

“Our analysis shows a single SLS Block 1B will cost at least $2.5 billion to produce—not including Systems Engineering and Integration costs—and NASA’s aspirational goal to achieve a cost savings of 50 percent is highly unrealistic,” Martin wrote in an audit of the agency’s plans, which was published on Thursday.

The main problem with the SLS rocket is not its performance—the vehicle’s debut during the Artemis I mission in late 2022 was virtually flawless—but rather its extremely high cost. Independent reviews of the vehicle, which Congress mandated that NASA build more than a decade ago, have found that NASA is unlikely to have a sustainable deep space exploration program built around such an expensive heavy-lift rocket.

Digging into Martin’s report, it’s not difficult to see why. The SLS rocket is powered by four main engines derived from the Space Shuttle program. The cost of these four engines is $582.7 million, or $146 million per engine. This means that a single engine on NASA’s rocket costs roughly the same amount that the space agency paid for an entire mission on the Falcon Heavy rocket — $178 million for the Europa Clipper spacecraft.

The Psyche mission that launched on a Falcon Heavy last week cost an estimated $113 million. SLS has a lot more lift than Falcon Heavy does but not that much more, dollar for dollar.

Starship — when Washington finally lets testing proceed — is supposed to bring costs down dramatically from even that.