Although NASA's microgravity research program certainly includes research conducted on materials science and materials processing, the reality is that this program is much broader in its scope. Specifically, current microgravity research, viewed as a laboratory science, is also broadly directed toward fundamental studies in physics, chemistry, and biology. Thus, the acceleration of gravity is becoming a meaningful, independent, experimental parameter. This approach is analogous to that employed for more than a century in low-temperature physics, in which diverse phenomena are studied in a cryogenic regime where temperature is the primary independent variable that may be set arbitrarily close to zero. In summary, microgravity research involves strong elements of traditional laboratory science, in contrast with the observational science that constitutes most of the NASA space science program.
Experiments often involve controlled model systems and exacting parameter settings.
Numerous experimental conditions must be explored, and repeat experiments must be conducted for each investigation in order to understand the phenomena of interest and establish, according to scientific standards, the validity and reproducibility of the data. By contrast, however, the U.S. microgravity research program has produced in its limited experience of in-orbit experimental time only a few score samples and sets of data that meet high scientific standards. This situation is not surprising in view of the fact that humans have been able to make observations in the absence of gravity for less than a quarter of a century and that serious laboratory experiments have been feasible in space for only about 15 years. The decade of the 1990s represents the first phase of experimentation in microgravity and the potential advent of a true laboratory science in space. More recently, the 1992 report Toward a Microgravity Research Strategy 3 began to lay a foundation for a more mature research program, and the current report is a continuation of that effort.