figure is used by NASA for mission planning, and although the time actually devoted on-orbit may differ, the end result is that the tasks that are planned on the ground for 20 hours represent one-half of the on-orbit available time for one crew member. A further complicating factor in deciding how to apportion the 20 hours per week available for science payload operations stems from the fact that, according to the agreements currently in place with the international partners, the 20 available hours will be allotted, on average, in the following manner: 10 hours for Russia, 7.5 hours for the United States, and 2.5 hours for all others. This arrangement makes the situation even bleaker for U.S. investigators. The dramatic reduction in available crew time results in a space station with less time available for research than was available 30 years ago on Skylab, and it will critically compromise the ability of the ISS to support a significant program of science research. This limitation has an impact on every discipline examined, from a potential total elimination of the ability to achieve even a modicum of meaningful work on the ISS in many areas of radiation biology, systems physiology, crew behavior and performance, and fundamental biology, to lesser impacts on disciplines such as plant science, materials science, fundamental physics, combustion science, and fluid physics. Even these potentially less-affected fields will probably sustain significant negative impacts when they are forced to compete with the remaining scientific complement for the minimal time available.

Distributing the 20 hours of available time among several crew members ensures that no crew member will have more than a small percentage of his or her time associated with science activities. This creates inefficiencies and a lack of continuity. Past spaceflight experience has shown that science is served best when crew members train in depth on experiments and have a substantial portion of their on-orbit time dedicated to science.

International Partner Participation

The numerous revisions to the ISS configuration have resulted in strong objections by international partners that NASA is no longer in compliance with agreements on ISS development and utilization. To date, these compliance issues have not been resolved. This raises questions about whether the international partners will continue to support the ISS at previously planned levels. Since the announcement of the Core Complete configuration for the ISS, a large portion of the ESA budget for ISS support has been frozen, and NASDA has also announced that it expects to make substantial cuts in its ISS budget. Loss of science facilities that were to be provided by partners could have serious consequences for an already hobbled science program. For example, if the Japanese experiment module exposed facility were not available, the fundamental physics program on the ISS would be all but eliminated.

Experiment Facilities, Equipment, and Upmass

As shown in Table 1.1, many experiment racks have been eliminated or delayed indefinitely in the redesign of the ISS. In addition, the modules containing the functional equipment that will go into the remaining racks have also been reduced significantly in number, worsening an already dramatically reduced capability. The disciplines that are affected most severely by these reductions are materials science, fluid physics, fundamental biology, and muscle and bone physiology. For instance, the deletion of the animal habitat and the lengthy delay in the 1-g centrifuge severely limits research in systems physiology, fundamental biology, radiation biology, and bone and muscle physiology. The animal habitat is essential for basic studies on rats and mice, and the 1-g centrifuge is critical for providing valid in-flight controls for animal and plant experiments. The 1-g centrifuge could also be used in the future to support combustion research. The absence of these facilities significantly limits what kind of research can be proposed and implemented on the ISS.

Facilities for materials science research have been reduced dramatically. The Rev. F plan called for a facility with three research racks, a rack-mounted materials science laboratory, 13 experiment



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