1. What are the practical methods for achieving mobility?

2. For surface missions, what are the associated needs for sample acquisition?

3. What is the state of technology for planetary mobility in the United States and elsewhere, and what are the key requirements for technology development?

4. What terrestrial field demonstrations are required prior to spaceflight missions?

Mobility may be achieved by a variety of techniques, including balloons, aircraft, rovers, and hoppers. In addition, the concept of mobility can be thought to encompass devices for instrument positioning, digging, drilling, and sample manipulation. Indeed, the history of planetary exploration contains a number of examples of the application of mobility. Conventional flybys and orbiters, together with entry probes, are explicitly excluded from consideration in this study because these mission modes have already been discussed extensively. Given that COMPLEX’s expertise is in the planetary sciences rather than engineering or robotics, and that the primary reason for employing mobility is to enhance the return of valuable scientific data, this report is focused on scientific rather than technological issues. COMPLEX therefore restricted its attention to six case studies, representative of the goals, environments, disciplines, and technologies drawn from previous COMPLEX and NASA reports:

• What is the nature of the circulation in the lower atmosphere on Venus?

• What tectonic processes are responsible for the structural and topographic features present on Venus?

• Is there evidence for extinct or extant life on Mars?

• What is the physical and chemical heterogeneity within small bodies such as asteroid 4 Vesta?

• What drives the zonal winds in the jovian atmosphere?

• What is the internal structure of Europa?

These six case studies are discussed in Chapter 2 .

The most important conclusion from this study is that mobility is not just important for solar system exploration—it is essential. Many of the most significant and exciting goals spelled out in numerous NASA and National Research Council documents cannot be met without mobile platforms of some type.

A second conclusion is that the diversity of planetary environments that must be explored to address priority scientific questions requires more than one type of mobile platform. Thus, the simultaneous development of some combination of wheeled rovers, aerobots, aircraft, touch-and-go orbiters, and cryobots is not only justified but is also necessary, as long as there is a scientific justification for the development of each mobile platform. Technology development funds are likely to be scarce and so should be allocated only after a vigorous peer review of the proposed mobility device’s technical feasibility and the scientific applications for which it will be used. Technology development activities should be undertaken by the best-qualified individuals and teams within NASA, industry, and academia, as determined by peer review.

With some exceptions, the current technical development efforts are appropriate and well focused. However, it is instructive to compare the tenor of recommendations in science-oriented presentations and of science-centered working groups with the thrust of technical development efforts. The science sources emphasize the need for very capable mobile platforms with these characteristics:

• Synergy of instruments, that is, a suite of mutually complementary instruments rather than either a small number of instruments or many instruments that are independently conceived and developed;

• Extensive range and long lifetime; and

• One or more manipulative devices, such as claws, drills, and the like, some of which are likely to be complex and difficult to develop.

These characteristics define a mobile platform that is fairly large and potentially rather complex. In contrast, the main thrusts of technical development, especially of rovers, are directed at reducing their size and increasing

Front Matter (R1-R4)

Contents (R5-R6)

1. Charter and Organization of the Board (1-7)

2. Activities and Membership (8-35)

3. Summaries of Major Reports (36-58)

4. Short Reports (59-74)

5. Congressional Testimony (75-77)

6. Cumulative Bibliography (78-86)