of a large number of research facilities, supporting hardware, and experiment modules. For convenience, this scenario is referred to as “proposed Rev. G” in this report.3


The task group was extremely concerned about the schedules for the development and deployment of ISS research facilities that were presented by NASA during the course of this study. In the task group’s view, a fully equipped ISS—including adequate crew support, electrical power, and experiment accommodations—needs to be in operation if NASA’s scientific objectives are to be achieved. Proposed reductions in crew size, facilities, and power have caused great concern in the scientific community. Specific concerns expressed by groups representing the ISS user community (Sekerka, 2001; Fettman, 2001; Katovich, 2001) have strengthened this task group’s view that the future of science on the ISS would be severely impaired under the proposed Rev. G scenario.

Based on a review of NASA’s program data—including ISS experiments planned, rates of proposal submission, and success and student funding levels—as well as input from members of the ISS user community, the task group reached the following conclusions:

  • The U.S. scientific community is ready now to use the ISS.

  • However, this readiness cannot be sustained if:

    • The proposed reductions in the scientific capabilities of ISS take effect, or

    • Slippage continues in both the development and science utilization schedules for the ISS as currently proposed, or

    • Uncertainties continue in funding for science facilities and flight experiments on the ISS.

Adding Annual Shuttle Missions for Laboratory Science

Proposed reductions in available experiment accommodations, crew, and power raise concerns about the ultimate functionality of ISS and thus directly affected the task group’s consideration of whether additional shuttle flights dedicated to science should be flown during ISS assembly and outfitting.

The task group concluded that ISS science could not proceed without the appropriate crew support and a clearly defined time line for deployment and completion. If the present Rev. F design and schedule were maintained, then it would be preferable to proceed with construction of a fully equipped ISS rather than divert resources to fly ISS science on additional shuttle missions. However, if ISS capabilities were to be reduced below Rev. F levels and there were no annual microgravity research-dedicated shuttle flights, then the viability of the overall program in microgravity research would be seriously jeopardized, as would the ability of NASA to achieve its stated scientific goals for the ISS. Therefore, if it becomes apparent that the ISS will not be available for meaningful microgravity research by the beginning of FY 2006, then annual shuttle flights dedicated to microgravity experiments should be made a part of the program.

Specifically, the task group recommends that:

  1. Assuming that the Rev. F schedule and capability are achieved, then:

    1. If ISS development were to be the funding source for additional microgravity shuttle flights, then no additional shuttle flights should be planned for microgravity research.


Though based on NASA’s draft Rev. G Assembly Sequence (4/01), this scenario is currently referred to by NASA as the 2002 Presidential Budget Submission.

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