"For example, NASA should enhance contract management and oversight to improve program outcomes," the report said. "NASA's past approach in this area has left it ill-positioned to identify early warning signs of impending schedule delays and cost growth or reap the benefits of competition."
The report recommended that NASA provide sufficient cost and schedule reserves to address unforeseen risks, and also begin producing "realistic cost estimates and assessments of technical risk."
"NASA has historically provided little insight into the future cost of these human spaceflight programs, limiting the information useful to decision makers," the report said.
NASA’s goal of sending two humans to the Lunar south pole by 2024 depends on the successful completion and integration of three systems, the giant SLS [Space Launch System] rocket, the Orion crew capsule and the ground control unit, the release said.
NASA senior leaders have acknowledged that the agency is unlikely to meet previously revised 2020 test launch date, while the GAO report warned that issues uncovered during integration and testing may push the date as late as June 2021.
In addition, GAO estimated that NASA's calculations of cost growth for the Space Launch System program is understated by more than $750 million.
At President Donald Trump’s insistence, NASA set a 2024 deadline for the first human flight to the Moon since the final Apollo 17 mission in December 1972 - four years earlier than originally planned.