An anonymous reader shared this report from the senior space editor at Ars Technica:
In a new report, the federal department charged with analyzing how efficiently U.S. taxpayer dollars are spent, the Government Accountability Office, says NASA lacks transparency on the true costs of its Space Launch System rocket program. Published on Thursday, the new report (see .pdf) examines the billions of dollars spent by NASA on the development of the massive rocket, which made a successful debut launch in late 2022 with the Artemis I mission. Surprisingly, as part of the reporting process, NASA officials admitted the rocket was too expensive to support its lunar exploration efforts as part of the Artemis program. “Senior NASA officials told GAO that at current cost levels, the SLS program is unaffordable,” the new report states…

Moreover, the report indicates that NASA has not regularly updated its five-year production cost estimates for the rocket. The report also cites concerns about development costs of future hardware for NASA’s big-ticket rocket program, including the Exploration Upper Stage. Another problem with NASA’s cost estimates is that they do not appear to account for delays to Artemis missions. It is probable that the Artemis II mission, a crewed flight around the Moon, will launch no earlier than 2025. The Artemis III crewed landing will likely slip to at least 2026, if not more, with additional delays down the line…

NASA officials interviewed by the Government Accountability Office acknowledged that they were concerned about the costs of the SLS rocket. “NASA recognizes the need to improve the affordability of the SLS program and is taking steps to do so,” the report states. “Senior agency officials have told us that at current cost levels the SLS program is unsustainable and exceeds what NASA officials believe will be available for its Artemis missions.”