This week, the US Government Accountability Office reported on progress the space agency is making to prepare the Space Launch System rocket, Orion spacecraft, and launch systems at Kennedy Space Center for future missions. NASA is making progress on these complex integration activities, the report finds, but the space agency has a long ways to go to make a test flight in late 2019 or early 2020.

One surprise in the report is that NASA still has not provided Congress (or anyone else) with cost estimates for the first crewed mission of the SLS rocket and Orion spacecraft, which could occur in 2023 or later. This "Exploration Mission 2," which would entail flying a crew of four into deep space and possibly delivering the first component of a space station into lunar orbit, would mark the first human mission after 12 years of development of the rocket and nearly two decades of work on Orion.

"Establishing a cost and schedule baseline for NASA’s second mission is an important initial step in understanding and gaining support," the report states of NASA's exploration plans, which include building the deep space station and then going to the lunar surface or on to Mars. "NASA’s ongoing refusal to establish this baseline is short-sighted, because EM-2 is part of a larger conversation about the affordability of a crewed mission to Mars."

The government report notes that it previously recommended to NASA and Congress that costs of the first (and subsequent) human missions be calculated and disclosed three years ago in 2014. Since then, the report says, a senior official at NASA's Exploration Systems Development program, which manages the rocket and spacecraft programs, replied that NASA does not intend to establish a baseline cost for Exploration Mission 2 because it does not have to.

This response must have struck investigators with the General Accountability Office—Congress' auditing service—as a bit in-your-face. Later in the report, the director of acquisition and sourcing management for the accountability office, Cristina Chaplain, notes that, "While later stages of the Mars mission are well in the future, getting to that point in time will require a funding commitment from the Congress and other stakeholders. Much of their willingness to make that commitment is likely to be based on the ability to assess the extent to which NASA has met prior goals within predicted cost and schedule targets."

Essentially, then, Congress does not have any good information about how much NASA's plans to explore the Moon and Mars might cost. In a written response to the report, NASA's chief of human spaceflight operations, William Gerstenmaier, said this was not a problem.

"NASA believes it has the processes in place to provide stakeholders insight to cost, schedule, and risks," Gerstenmaier wrote earlier this month. "Cost estimates and expenditures are available for future missions; however, these costs must be derived from the data and are not directly available. This was done by design to lower NASA's expenditures. NASA does not think that structuring acquisition and implementation to ease accounting on a mission-by-mission basis is prudent as it would result in higher overall program costs and is not in keeping with the nature of the program."

The ball is now in Congress' court. In the past, they have paid limited attention to what NASA will actually do with SLS and Orion, as they've been more interested in the development of those vehicles. Now, however, Congressional auditors are poking them, saying they ought to care about the actual costs of any missions NASA might undertake. It will also be interesting to see if the White House nominee to lead the space agency, Jim Bridenstine, decides to become more forthcoming about the true cost of NASA's human exploration plans.