
"The cost and schedule estimates for the National Aeronautics and Space Administration's (NASA) Space Launch System (SLS) program substantially complied with five of six relevant best practices, but could not be deemed fully reliable because they only partially met the sixth best practice--credibility. While an independent NASA office reviewed the estimate developed by the program and as a result the program made some adjustments, officials did not commission the development of a separate independent estimate to compare to the program estimate to identify areas of discrepancy or difference. In addition, the program did not cross-check its estimate using an alternative methodology."