role of science in any future program of human exploration of the solar system.

Given the often lofty, but still ill-defined, human exploration aspirations, what is the role of science in a Moon/Mars program? CHEX started with the recognition that one of the major goals in the National Aeronautics and Space Administration's (NASA) original charter was the acquisition of new scientific knowledge about space and the terrestrial environment. Indeed, scientific goals have always played an important part in NASA's activities. Thus it is natural to expect that science will play a major role in any future program of human exploration, as it did in Apollo and in all subsequent piloted spaceflight programs. The specific nature of that role and the way in which the scientific community has historically interacted with human space exploration will be dealt with in the third CHEX report.

It is not surprising then, that many, if not all, concepts for human exploration of the Moon and Mars include scientific investigations. Many proponents also propose using the Moon as an observational platform from which to conduct astronomical and space physics studies.

Is science then the motivation for a Moon/Mars program? This question was answered in the negative by the National Academy of Sciences and National Academy of Engineering in a report on space policy prepared in 1988. It stated that “the ultimate decision to undertake further voyages of human exploration and to begin the process of expanding human activities into the solar system must be based on nontechnical factors. ”⁷ In other words, the expansion of human presence and activity into the solar system does not demand any a priori scientific research component beyond the enabling research needed to provide for the health and safety of the astronauts (see next section).

Nevertheless, recognizing the need for enabling research and that piloted flight can result in new or modified space science opportunities, the U.S. research community has the opportunity and obligation to provide the best and most constructive scientific advice it can to help shape the political and technical decisions regarding piloted flight.⁸ Accepting such a role commits scientists to participating in establishing human exploration strategy and goals, mission planning, management, implementation, and analysis of results. During mission design and operations, scientists must participate to ensure optimal scientific return. Part of that optimization is the inclusion in the crews not only of people trained to perform particular scientific tasks, but also of experienced scientists. Indeed, scientist-astronauts have an important role to play in planning, postmission analysis, and preparations for future exploration.

Since the end of the Apollo program in 1972, humans have not set foot on another body in the solar system. The Apollo experience involved hundreds of scientists in many disciplines. Although science was not empha-