Readiness Issues Related to Research in the Biological and Physical Sciences on the International Space Station (2001)

The second charge to the task group in phase 1 of this study was as follows: “Complete an assessment of the relative costs and benefits of either dedicating an annual space shuttle mission to life and microgravity research during assembly of the ISS or maintaining the current schedule for ISS in place.”

There were numerous factors that had to be taken into account by the task group and NAPA when considering a question as complex as this one. Because the configuration of the ISS was in a state of flux, the task group was not able to obtain firm estimates of the ISS’s projected capabilities or their scheduled availability. Based on presentations from NASA personnel and other NASA materials, the task group selected two scenarios. The first envisioned configuration and capabilities as per Rev. F. The second envisioned a notable decrement in capability (proposed Rev. G). In considering both scenarios, the task group’s intent was to bound the potential capabilities and provide a context in which operational recommendations could be made in a more informed manner.

A number of issues are affected by the potential redesign scenarios. Several capabilities are pacing items. For instance, cancellation or delay of the crew return vehicle limits the crew size to three. This means that at best, the equivalent of half of one crew member would be available to conduct science, according to briefings by NASA. Such a limitation would severely affect the science that depends on crew member participation as operators, observers, or subjects. Examples include nearly every type of biomedical research planned for the ISS, including that needed for countermeasure development, the onboard analysis of protein crystals, most glovebox experiments, and any physical science experiment requiring sample preparation or postexperiment manipulation. If, as seems likely, maintenance of the ISS requires the full attention of the downsized crew of three, then the ISS becomes ineffective as a platform for laboratory research.

Loss, delay, or significant downscaling of the Centrifuge Accommodation Module would preclude the performance of critical, onboard control experiments, without which valid interpretation of life science microgravity data becomes tenuous at best. The proposed removal of a major solar array wing may result in a significant reduction in power available for microgravity research. Many of the facilities, such as the furnaces used by materials science experiments, would require large amounts of power, as would certain life science facilities such as the centrifuge.

In addition to the changes that would seriously affect, or even cripple, a wide range of science disciplines, a number of proposed changes would target individual research disciplines. Reduction in the number of racks for research—such as the proposed reduction¹ of the three-rack fluids and combustion facility to a single fluids rack, the cancellation of two of the three materials science racks as well as most of the experiment module inserts for the remaining rack, and elimination of the mammal, plant, and cell culturing habitats for the Centrifuge Module—would have a major detrimental impact on materials and fluids research and eliminate most combustion and fundamental biology research from the ISS (see Table 2.4 in Chapter 2 and Figure 3.1).

FIGURE 3.1 Habitat modules in the Centrifuge Accommodation Module that would be eliminated under proposed Rev. G. Dashed lines are drawn around the deleted habitats. SOURCE: Kathie Olsen, Acting Associate Administrator, presentation at NASA Headquarters to the Biological and Physical Research Advisory Committee on June 14, 2001.

The cost-benefit issues of flying additional shuttle research missions are discussed in detail in the NAPA analysis performed for this study (see Appendix A) and are only summarized here. There are both financial and opportunity costs and there are benefits that are both subjective and tangible. In brief, the costs and benefits considered in the NAPA analysis fall into the following categories:

• Cost of mounting new microgravity research missions

  1. SPACEHAB lease costs (double research module);

  2. Selection, mission design, preparation, integration and testing, operations, deintegration and data analysis;

  3. Marginal cost of an added shuttle flight; and

  4. Cost impact of any ISS schedule slip as a result of diverting assembly funds.

• Benefit of maintaining ISS assembly without perturbing the schedule

  1. Avoidance of high-cost schedule slips;

  2. Likelihood of an earlier opportunity to begin ISS-based research;

  3. Less turmoil induced in the ISS program; and

  4. Focusing of all program activity on single target—outfitting and using the ISS.

• Benefit of adding shuttle research flights

  1. Ensures that at least some low-gravity research not requiring long-duration exposure is accomplished;

  2. Provides near-term opportunities for flight and scientific advancement;

  3. Enhances continuity of investigators in the biological and physical sciences program by providing near-term access to a microgravity environment;

  4. Sustains readiness by maintaining active participation of the investigator base;

  5. Demonstrates NASA commitment to support of microgravity activities; and

  6. Provides fire safety data in support of ISS outfitting.

Each of these points is analyzed in the NAPA report (Appendix A) and will not be repeated here. Utilizing the results of the NAPA analysis and its own evaluation, the task group came to conclusions on several questions relevant to this study.

Prior to the establishment of the ISS, microgravity research on the shuttle was substantial, in both physical sciences and biology. Many of the questions being posed for ISS flight could initially be addressed on the shuttle. Longer-term experiments (e.g., the effects of microgravity on the long-term growth of organisms) cannot be performed on the shuttle. The task group unanimously agreed that shuttle flights were worthwhile, but recognized the importance of longer-term experiments, which by their very nature would have to be performed on the ISS.

To maintain high-quality microgravity research, a critical mass of investigators must exist in each field. The inability of researchers to attract graduate students and postdoctoral fellows for the study of microgravity has the potential to cascade into the total loss of that critical mass. If new students are not recruited now, there will be few faculty to recruit them later.

In the absence of a crew return vehicle (critical in case of a disaster) and the habitation module, which would result in a lack of sufficient crew and crew time (now estimated as half a crew equivalent per week) to handle experiments, as well as the critically needed life sciences Centrifuge Accommodation Module, state-of-the-art experiments cannot be performed on the ISS (see Table 3.1 for a comparison of ISS with other platforms). If this occurs, more investigators will become convinced that there are no worthwhile opportunities in microgravity research. The end result will be a further decrease in the ability to recruit new students and a further diminution in the size of the community trained to do research in microgravity aboard the ISS.

As previously discussed, there was not a defined scenario reflecting recently proposed budget constraints provided to the task group by NASA; hence, the task group bounded the problem with two alternative scenarios. These scenarios supplied a framework from which conclusions and recommendations could be made. In phase 2 of this report, the task group anticipates that sufficient information will be available to make more concrete recommendations. The two scenarios were based on Rev. F² and proposed Rev. G.³

Against this background, the task group makes the following recommendations:

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.

   2. If funding were to be provided from new sources, then it would be highly beneficial to fly additional annual flights until the ISS (with Rev. F capabilities) is complete.

2. Assuming that the proposed Rev. G schedule and capability are selected, then:

   1. If capabilities were to be reduced according to Rev. G projections, then annual shuttle flights devoted to science should be flown until the ISS reaches either the research capability planned for “assembly complete” under Rev. F or a similar level of capability that has been reviewed and approved by an independent body of scientists that can credibly represent the interests of the ISS user community.

The task group unanimously agreed that a fully equipped ISS as defined in Rev. F—including adequate crew support, electrical power, and experiment accommodations—is needed if NASA’s stated scientific ISS goals are to be realized. If ISS capabilities were to be reduced (as in proposed Rev. G) and there were no annual shuttle flights dedicated to microgravity research, then the viability of the overall program of research in microgravity would be seriously jeopardized, as would be the ability of NASA to achieve its stated scientific goals for the ISS. If it becomes apparent that the ISS will not be available for microgravity research by the beginning of FY 2006, then annual shuttle flights dedicated to microgravity experiments should be made a part of the program. Beginning 2 years ahead, in FY 2004, plans to use the shuttle should be integrated into the overall NASA mission planning. These recommendations all assume that space shuttle microgravity missions STS-107 and STS-123 (R2), planned for 2002 and 2004, respectively, are conducted as scheduled. And, finally, the activities defined above should not be accomplished in a manner that would jeopardize the sustainability and readiness of the microgravity research program.