"GAO found that the Orion program's cost and schedule estimates are not reliable based on best practices for producing high-quality estimates. Cost and schedule estimates play an important role in addressing technical risks. ... For example, the cost estimate lacked necessary support and the schedule estimate did not include the level of detail required for high-quality estimates. Without sound cost and schedule estimates, decision makers do not have a clear understanding of the cost and schedule risk inherent in the program or important information needed to make programmatic decisions. ... NASA and the Orion program have made some programmatic decisions that could further exacerbate cost and schedule risks. The Orion program is executing to an internal schedule with a launch readiness date of August 2021, which has a lower confidence level than its commitment baseline. This means that NASA is accepting higher cost and schedule risk associated with executing this schedule .... The lack of cost reserves has caused the program to defer work to address technical issues and stay within budget. As a result, the Orion program's reserves in future years could be overwhelmed by work being deferred. Program officials told GAO that they have not performed a formal analysis to understand the impact that delaying work might have on the available reserves since the program was confirmed. Without this type of analysis, program management may not have a complete understanding of how decisions made now will affect the longer-term execution of the program."
"... the SLS program has not positioned itself well to provide accurate assessments of core stage progress - including forecasting impending schedule delays, cost overruns, and anticipated costs at completion - because at the time of our review it did not anticipate having the baseline to support full reporting on the core stage contract until summer 2016 - some 4.5 years after NASA awarded the contract. Further, unforeseen technical challenges are likely to arise once the program reaches its next phase, final integration for SLS and integration of SLS with its related Orion and Exploration Ground Systems (EGS) human spaceflight programs. Any such unexpected challenges are likely to place further pressure on SLS cost and schedule reserves. ... NASA officials stated that this review will have limited discussion of cost and schedule. Proceeding ahead without reassessing resources, however, could result in the EGS or SLS program exhausting limited resources to maintain pace toward an optimistic November 2018 launch readiness date. ... In July 2015, GAO found that SLS's limited cost and schedule reserves were placing the program at increased risk of being unable to deliver the launch vehicle on time and within budget."