Review of NASA Plans for the International Space Station (2006)

According to the materials presented to the panel,^a the ISS today is approximately 50 percent completed. Issues surrounding the ISS as a facility for research, technology demonstration, operations demonstration to support exploration appear to fall into three categories: the completion of construction, the post-shuttle logistical support, and crew deployment.

While the panel did not receive substantive information about completing construction of the ISS in NASA briefings, nearly all of them referred to it. The rest of this chapter is based on what the panel inferred about NASA’s plans from those briefings and other information provided to it. The shuttle will be decommissioned at the end of 2010. The current goal is 19 shuttle flights, which will allow deployment of most of the major planned facilities. Currently, the shuttle is the only transportation system capable of deploying the large ISS structural components and research modules. The ISS external configuration remains as previously planned, with the exception of the deletion of the centrifuge accommodation module (CAM) and the Russian science power module (SPM). Animal holding facilities and the life sciences glove box (both would have been internal components of the CAM) were also deleted.^b

Otherwise all major facilities are planned to be deployed by the shuttle. Examination of documentation provided to the panel indicates that several research support facilities have been deleted in concert with cancellation of the research program that would have utilized them.^c In addition to the deletion of the CAM and the Russian SPM, some logistics flights were deleted, reducing the number of planned shuttle flights from 28 to 19. To build schedule margin, the program will endeavor to fly extra flights in some years. Given that shuttle flights are being delayed and that all future flight schedules are unsure, the planned ISS configuration might not be completed by 2010, which puts ISS exploration mission objectives at risk. It appears that there are no plans to provide an alternative to the launch-by-

shuttle of ISS structural components and research modules if the shuttle does not complete this task by 2010.

A robust logistics capability not only will maintain the basic functioning of the ISS facility but also will be paramount in accomplishing ISS exploration mission objectives. Logistics flights to the ISS will deploy crew supplies; maintenance equipment, including replacement spares; specific research experiments and associated equipment and samples; and, finally, technology demonstration hardware and associated provisions.

Logistics requirements can be categorized as either pressurized logistics for internal use or unpressurized logistics for external use. The size and shape of unpressurized logistics are such as to prevent them from being handled internally. NASA suggested that logistics requirements after 2010 over and above those provided by the current baseline Progress flights, the European Space Agency’s automated transfer vehicle (ATV) flights, and the Japanese H-II transfer vehicle (HTV) flights will be provided by a combination of a yet-to-be-procured U.S. commercial cargo vehicle, the crew exploration vehicle (CEV) pressurized cargo system, the cargo delivery vehicle (an unpressurized CEV derivative), and additional Progress, HTV, and ATV flights. The capabilities of each element in the combination, the acquisition schedules, and the funding requirements have not been specified in enough detail to give the panel confidence that ISS exploration mission objectives have a high likelihood of being fulfilled. This suggests that there would be significant value in developing a detailed plan to provide the post-shuttle logistics system.

Although no clear data were provided on the amount of crew time required to accomplish the planned ISS research, technology demonstrations, and operations demonstrations, it is unlikely that a team of three will be sufficient. Nor were plans for increasing the crew size to six discussed in detail. A discussion and review of other NASA materials suggested several options for crew deployment. NASA described Notional Scenario 1,¹ which provided for a crew of six in 2015. Notional Scenario 2 provided for a crew of six in 2009. In response to questions, NASA indicated that the ISS might be capable of sustaining a crew of six in 2008 at the earliest, depending on deployment of the advanced environmental control and life support systems. The panel believes that in order to accomplish ISS exploration mission objectives, the crew complement has to be increased as soon as practicable.

The following steps are needed to make possible the research, technology demonstrations, and operations demonstrations required to enable plans for human exploration of the Moon and Mars:

1. NASA should plan options and decision points for obtaining a post-shuttle logistics capability for maintaining the ISS facility, for supporting the flight crew and research, and for demonstrating the technology and operations that will enable exploration missions.

2. NASA should establish priorities and develop back-up plans to enable the post-2010 deployment of large ISS structural components and the research facilities required to accomplish exploration mission objectives.

3. NASA should develop plans to deploy six persons to the ISS as soon as practicable, preferably in 2008.

1. National Aeronautics and Space Administration (NASA). 2004. Bioastronautics Critical Path Roadmap. NASA, Washington, D.C.