The Space Launch System (SLS) program is making solid progress on the SLS design. However, the National Aeronautics and Space Administration (NASA) has not developed an executable business case based on matching the program's cost and schedule resources with the requirement to develop the vehicle and conduct the first flight test in December 2017 at the required confidence level of 70 percent. NASA uses a calculation referred to as the "joint cost and schedule confidence level" to estimate the probable success of a program meeting its cost and schedule targets. NASA policy usually requires a 70 percent confidence level for a program to proceed with final design and fabrication. GAO's work on best practices has shown that programs that do not establish an executable business case that matches requirements--or customer needs--to resources, such as schedule and funding--are at increased risk of cost and schedule growth.
The program is satisfying many of NASA's metrics that measure progress against design goals, such as requirements for design maturity. According to the program's risk analysis, however, the agency's current funding plan for SLS may be $400 million short of what the program needs to launch by 2017. Furthermore, the development schedule of the core stage--which drives the SLS schedule--is compressed to meet the 2017 launch date. NASA also faces challenges integrating existing hardware that was not originally designed to fly on SLS. For example, SLS is using solid rocket boosters from the Constellation program, but integrating a new non-asbestos insulating material into the booster design has proven difficult and required changes to the booster manufacturing processes.