NASA began developing the Space Launch System (SLS) in earnest when the Space Shuttle program ended in 2011. This super-heavy-lift rocket will be key to NASA's return to the moon, but the escalating costs have some inside and outside the agency concerned. The Government Accountability Office (GAO) has just released a report that brands the SLS as "unsustainable."
NASA's cost estimates at each stage have been very optimistic, and the GAO objects to the agency's decision to monitor cost via the five-year production and operations cost estimate. The GAO report says these are poor tools to control costs, and NASA hasn't even been consistent about updating the five-year estimates.
So far, NASA has spent $11.8 billion developing the SLS. The 2024 budget proposal includes another $11.2 billion to see the program through 2028. Will that be enough? The GAO says, no, probably not. A previous report by NASA's inspector general suggested the $2 billion launch cost for each Artemis mission was unrealistic, and the real number was closer to $4.1 billion.
The Artemis program has suffered from numerous delays, and the report says that NASA has not been accounting for how these schedule changes affect costs. The SLS and Orion capsule contain components built all over the US (in a lot of influential congressional districts, naturally). Even minor changes cause logistical challenges and ballooning costs. However, the GAO says that at least one NASA official claimed additional SLS delays would not impact the bottom line, which seems hard to believe. On the other hand, NASA's leadership did admit that the SLS is too expensive to support the lunar program as currently envisioned.
So what's the solution? The GAO report (PDF) boils down to 'NASA should do everything better.' The vague bullet point suggestions include stabilizing the flight schedule, achieving learning curve efficiencies, encouraging innovation, and reducing acquisition costs. NASA has struggled to cut program costs, though.
As it currently stands, Artemis II is on the books for late 2024, and the Artemis III moon landing follows in 2025. However, the GAO projects that Artemis II will launch no earlier than 2025, and Artemis III will be lucky to get off the ground in 2026. The GAO notes that each component of the SLS gets more expensive as time goes on, and NASA's attempts to control costs aren't working. For example, NASA says it's working with Aerojet to make the new RS-25 engines for the SLS 30% cheaper. Yet, Ars Technica reports that NASA's own inspector general says the agency's calculations don't include project management or other overhead costs—expenses that scale up as timelines slip.
The version of the SLS we have now isn't even the final one. NASA hopes to move from the Block 1 design to more powerful Block 1B and Block 2 setups starting in Artemis IV and IX, respectively. The report does not attempt to estimate the cost of these design updates but notes that the creation of new components like the Exploration Upper State could be too expensive to fund.
