and mission assurance. In addition, the committee sought input from potential providers of future commercially procured human spacecraft, such as SpaceX and Sierra Nevada Corp., and from the Federal Aviation Administration (FAA), which is responsible for licensing commercial launch vehicles in the United States and is expected to play a role in licensing future commercial human spacecraft. And it received briefings on training practices of the Naval Reactors Program and the commercial airline industry.

The committee received substantial cooperation and assistance from the Flight Crew Operations Directorate, including the chief of the Astronaut Office and members of her staff. The committee assessed the information provided to it by FCOD in presentations and the planning tools used by FCOD and the Astronaut Office. That cooperation made it possible for the committee to explore all aspects of its task. Taking into consideration questions posed by the committee during its meetings and questions submitted directly to the Astronaut Office, in March 2011 the Astronaut Office produced a white paper containing substantial amounts of information directly relevant to the committee’s task.1 Throughout this report, the committee uses graphics provided by NASA in that white paper, which is referred to in the report as “NASA Astronaut Office 2011 White Paper.”


Question 1—Role and Size of the Flight Crew Operations Activities

NASA’s Astronaut Office, which is part of FCOD at JSC, is responsible for managing NASA’s Astronaut Corps, which the committee defines as the set of astronauts qualified to fly into space, excluding astronauts who have transitioned to management positions in the agency and are no longer eligible to fly space missions. The Astronaut Corps has been reduced substantially since it reached a peak of nearly 150 in 2000. In May 2011, the Astronaut Corps consisted of 61 persons, and NASA has projected a minimum required Astronaut Corps of 55-60 astronauts through 2016. In 2009, the agency selected a new class of nine astronaut candidates for addition to the Astronaut Corps in 2011. It is expected that the new class will compensate for any attrition and help to ensure long-term sustainment of a skilled U.S. Astronaut Corps.

Although NASA’s human spaceflight program and its post-shuttle crew requirements have not been well defined except in terms of the ISS, the committee concluded that the sizing of the Astronaut Corps to meet ISS crew requirements has been well modeled by using as input ISS crew selection, training and flight recovery times, and a post-shuttle force reduction plan. NASA uses a model to predict the minimum staffing requirements and then applies an arbitrary management margin to the result (Figure S.1).

According to a presentation by the chief of the Astronaut Office to the committee during its first meeting, the model produces a theoretical minimum and does not include several real-world constraints, such as mission-required skills mix, temporary or permanent medical disqualification, inability of astronauts returning from a long-duration mission to fly another long-duration mission at the end of the normal 1.5-year recovery period, and the desired pairing of inexperienced and experienced astronauts on new assignments. In light of those unpredictable constraints, a 25 percent margin, as shown in Figure S.1, is factored into the model used to determine the size of the Astronaut Corps that will meet the minimum manifest requirement.

The committee notes that in addition to substantially reducing the size of the Astronaut Corps recently, NASA has reduced the management margin that it applies to its model. The margin, which was 50 percent, was reduced in 2010 to 25 percent, apparently because of budget pressures. According to the chief of the Astronaut Office, “The corps requirements will always be greater than the manifest analysis, and 25 percent may not be enough margin.”2

The committee notes that new sources of uncertainty have been identified in the human spaceflight program. For example, a relatively new medical condition has been observed among astronauts returning from long-duration space missions: papilledema, a swelling of the optic disk. The condition has led to several Astronaut Corps mem-


1 NASA Astronaut Office, “Ensuring the Readiness of the Astronaut Corps: A White Paper,” NASA Johnson Space Center, Houston, Tex., March 25, 2011.

2 P.A. Whitson, Astronaut Office, “Presentation to the NRC Committee on Human Spaceflight Crew Operations,” presentation to the Committee on Human Spaceflight Crew Operations, January 6, National Research Council, Washington, D.C., 2011, p. 36.

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