Prepared Statement of Dr. Matthew B. Koss: “The Future of Human Space Flight” (part 2)
If researchers no longer had access the Space Shuttle or Space Station, then a vital research area in the advancement in the materials sciences would be halted.
With the indulgence of the Committee, I would like to briefly discuss my field of expertise and how orbital research has played a key role in promoting understanding of our physical world. One of the major thematic elements in the research and manufacturing of materials is what is termed the microstructure. The understanding and control of microstructure is one of the ultimate goals of both the materials scientist and materials engineer. A material’s microstructure includes not only what atoms make up a material (composition), but also how are those atoms arranged (structure).What is the geometry of these atomic arrangements and what patterns emerge? Microstructure is a vital theme in materials science because it appears in both major paradigms of material science. That is, the way a material is formed determines its microstructure, and a material’s microstructure determines how it behaves. This then, of course, determines whether or not a material is useful for a given engineering purpose.
Historically, during the emergence and development of materials science, scientists were most interested in the two microstructures that could be completely described, perfect single crystals and completely disordered glasses. Nonetheless, important aspects of a specimen’s properties depend on a range of complex microstructures that exist between these two extremes. They could not be addressed from a general scientific or engineering methodology until the description and behavior of those complex microstructures were better understood. For most materials, this analysis requires the understanding of how solids form from their melts. For metals and alloys, such an analysis further requires an understanding of what we call dendritic solidification.
During the past fourteen years my research activities have concentrated in the examination of microstructure as it concerns dendritic solidification. Dendritic solidification is the transformation of a molten liquid into a complex, tree-like branching crystalline microstructure. Dendrites are known to appear in the freezing of water, molten salts, ceramic materials, organic materials, and most importantly in the solidification of metals and alloys. I have been personally involved in the experimental investigation of the growth of thermal dendrites. With the aid of NASA’s orbital facilities and programs we have made substantial progress because the effective reduction in gravitational body forces on orbit enabled us to understand details of the process that we were not able to accomplish otherwise.
The NASA materials science program has also made substantial gains in the understanding of microstructure. Currently, through its flight programs, NASA is the leading governmental agency in promoting and enabling the understanding of microstructure.
With respect to dendritic solidification in particular, despite the recent advances, the following quote from 1999’s National Research Council’s (NRC’s) report on Condensed Matter and Materials Physics makes clear there is more to be done. The report states,Very significant progress has been made in the last decade in understanding dendritic pattern formation in crystal growth. That progress, however, has yet to have a major impact on efforts to predict and control solidification microstructures in industrially important materials. In part, the difficulty is that there remain some challenging scientific problems to be solved, such as the ‘mushy zone’. Another part of the difficulty is that there is relatively little effort in this area in the United States, especially in industrial laboratories.
Work remains to be done both in understanding additional details about dendritic growth, and in bridging the gap between our understanding of an isolated isothermal dendrite and the final, as-cast microstructure of metals and alloys. The “mushy zone” during dendritic solidification processes is the region where solidification is actively occurring, and the material is part liquid and part solid (hence the term “mushy zone”). This zone consists of many dendrites, each growing in a complicated manner, interacting with their neighboring dendrites. The ultimate scientific goal is to understand this process in its entirety. But to reach this goal, it is necessary to first understand how individual dendrites grow, both isolated from and subject to external influences. This is the substance of several NASA funded projects.
The fact that NASA has been funding research on dendrites since the mid 1970’s, both in ground and flight programs, and that the research is now so varied and so vibrant, is evidence of the success of NASA physical science in space program. Using the orbital environment to continue this progress in understanding dendrites is vital. If the access to orbit were eliminated, then the most fruitful avenue of advancement on this important topic will be halted. While orbital research is vital, I content that human tended scientific missions are not absolutely necessary to continued progress in our quest to understand more about microstructure.
And while I have mentioned research on dendrites specifically, I am mindful that the research in which I participate is but one of many examples of productive lines of research in materials science. There are many additional examples of important research being done in the fields of Fluids, Combustion, Fundamental Physics, and Biotechnology. Since I cannot speak authoritatively on these fields, I refer the Committee to experts in those scientific fields.
To the best of my knowledge, at this time, there are no alternatives for autonomous or remote operations of on orbit experiments if the Space Shuttle or Space Station were unavailable. NASA has extensive ground programs that use drop tubes, drop towers, and parabolic airplane flights to provide from 2 to 25 seconds of apparent weightlessness. These are valuable and productive programs in their own right, but they are not a substitute for long duration orbital flight experiments.
I believe that the Office of Biological and Physical Research in Space has begun to discuss an autonomous or remote platform, but no action or commitment to such a program has been made.
I do not have the necessary expertise to make a specific financial estimate of what a free flying, on orbit, autonomous or remote controlled facility would cost. However, I can detail the tradeoffs between an autonomous/remote facility versus that of continued human enabled facilities. In my view, these trade-offs favor the autonomous/remote facility.
NASA already has the appropriate expertise at the Office of Biological and Physical Research in Space and at the various field centers to design, built, launch, operate, and recover an autonomous/remotely controlled payload platforms. The only new feature would be the newly designed and built space flight hardware for these operations.
If experiments had to be designed for an autonomous/remotely controlled facility, there would be both cost increases and savings. The cost increases would be to design and built autonomous or remotely controlled experiments in place of those that were formerly designed for astronaut operation. Similarly, those experiments that were built to operate autonomously or remotely could be scaled back some because of the relaxation of constraints necessary for flight aboard a human tended spacecraft.
The greater cost savings would occur because there would be no need to launch and operate shuttles dedicated to physical science experiments. There would be significantly less upmass to the International Space Station for physical science experiments. The Space Station itself could be scaled back as there would be no need for laboratory space dedicated to physical science experiments, and there would be no requirements for astronauts to be trained or travel to orbit to conduct these physical science experiments.
In addition, there would be some secondary cost savings as well. Currently, payload experiments are designed and built to exacting standards so as to certify that a given experiment has a greater than 90% chance of success. This high standard is necessary since the cost and risk of bringing that payload to orbit is so high. If a new unmanned autonomous or remote facility could be brought online and made operational at a lower cost per launch, the probability of success standards could be relaxed to, say, 75%, with a much greater percentage reduction is design, construction, testing, certification, and operating costs. This is so because if a given experiment were not successful, it could be modified and re-launched on a future flight quickly and inexpensively. In other words, a whole new design and operating philosophy would occur with significant cost savings.
Lastly, with an autonomous or remote facility as described above, it would be significantly easier and more likely to maintain launch and operating schedules. The reliability of scheduling would also result in a cost savings and would give the program a consistency that would benefit all current investigators and help attract graduate students and post doctoral associates into the program.
It is very unlikely that a more ambitious mission for NASA, such as sending people back to the moon or to Mars, would be likely to provide materials science researchers with unique opportunities for experimentation. Materials science is a laboratory science aimed at understanding and controlling the inner workings of materials. Unlike like observational sciences and planetary geology, the moon and Mars have little or nothing to offer to the physical laboratory sciences.
The key element of the on orbit free fall environment for materials science researchers is the effective elimination, or great reduction, in gravitational body forces. This reduction effectively eliminates the hydrostatic pressure in fluids, and thereby effectively eliminates buoyancy, sedimentation, and natural convection while giving greater reign to other convective processes and surface effects. This allows a materials scientist to try to understand fundamental phenomena in how materials are formed and function in a way that is simply not possible on an Earth based, or other planetary, laboratory.
Naturally, if NASA had a more ambitious mission, such as sending people back to the moon or to Mars, materials science would be one of the enabling technologies, much like the present NASA sponsorship in materials for radiation shielding. The need for such enabling technologies would benefit materials science as there would be increased funding for certain lines of research. However that research work would be the more traditional Earth-based laboratory materials research and is not really different that that which is taking place in academic, national, and industrial laboratories today.
Additional Comments Related to the Specific Questions Submitted by the Chair
In addition to my statement directly addressing the specific questions posed by the Chair, I have a number of comments that indirectly address those questions.
Several of the questions addresses to me were specifically directed to my professional experience in condensed matter and materials physics. I answered these questions to the best of my ability. In addition, when I believed my knowledge to be up to the task, I inserted comments about other of the disciplines under the auspices of the Office of Biological and Physical Research in Space.
When colleagues heard that I was testifying here today, one said something like “Don’t say anything bad about Fundamental Physics.” Well I won’t. But I would like to do one better. I affirm the tremendous value of the research in combustion, fluids, fundamental physics, and materials science that has been done by brilliant and talented scientists, and it remains my fervent hope that this fundamental research will continue to take place on orbit. I cannot make, and will not attempt to make any value judgment that places one of these disciplines, even my own, above another.
I say this for the real fraternity I belong to is science, and when one science is diminished in competition with another, all are diminished. It is crucial that all sciences have a path to the future. A while back when the crisis in science funding occurred in the Office of Biological or Physical Research, a fellow materials scientist advised me to get out there and lobby for materials the way other scientists are doing for their discipline. To the extent that this was true, it was deleterious to all the so named “microgravity” sciences, and other sciences as well. I will not engage in that. Despite any criticisms I have expressed, I am a committed advocate of the on-orbit environment as one of many vital national resources for scientific advancement across the disciplinary boundaries.
Lest my advocacy for an autonomously or remotely operated facility for the physical laboratory sciences in low earth orbit be misinterpreted, I also favor a continued human presence in space. We may always need astronauts to assume certain risks human exploration and development of space. I agree with NASA when they say that “exploration is what great nations do” and “exploration is part of the human fabric.” Space shuttles and space stations may indeed be necessary to fulfill that need to explore. I am only advocating that a better balance be found for autonomous, remote and human enabled programs. I fully support NASA and the country in looking for a grand overarching mission, including that of the future of human space flight. However, the time has come to decouple the human exploration and development of space from the needs and benefits of conducting basic research in the laboratory physical sciences in low earth orbit.
I think that many scientists fear that if this decoupling takes place, that the basic laboratory physical sciences would disappear from NASA’s portfolio in favor of the more dramatic and compelling future of human space flight. I share that fear, and if that came to pass it would be a great shame. However, the cost of using astronauts to perform science experiments to gain public support of science in space is not justified. All the orbital experiments that can be conducted autonomously or remotely should be done in that mode. The Office of Biological and Physical Research portfolio is a vibrant and vital program. I truly believe that moving the physical science research program, and as much of the biological research program as possible, to a fully autonomous or remote facility would benefit both the program itself and be a great complement to NASA’s larger mission.
Conclusion
As stated earlier, NASA already has the appropriate expertise at the Office of Biological and Physical Research in Space and at the various field centers to design, built, launch, operate, and recover an autonomous/remote controlled payload platform. I believe, based on the way NASA has created and cultivated such a robust, professional and productive laboratory science program on orbit, that they could assuredly manage a tremendously productive autonomous/remote facility as a vital national resource, and do so at a reasonable and reduced cost and at greatly reduced risk.
Again, thank you for the opportunity to address you here today.
