1990 Update to Strategy for Exploration of the Inner Planets

7

Supporting Research and Analysis

The decade preceding the 1978 report included a fast succession of major and pioneering missions, with brief pauses for postmission synthesis. The 1978 report recommended both scientific instrument development and a "vigorous and ongoing program of data analysis and synthesis ... designed to foster interdisciplinary and comparative planetological research." These recommendations have been implemented. The last decade also has witnessed, however, significant advances related to NASAs objectives that were stimulated not only by new mission data, but also by new ideas and unexpected discoveries.

Several examples can be cited. First, the discovery of meteorites from the Moon and Mars on the Antarctic ice sheet provided unexpected new clues about planetary materials and raised critical questions about impact physics. This discovery and subsequent analysis have led to a new perspective on the transfer of materials between planets.

Second, the recognition of a geochemical cosmic signature on the Earth closely correlating with a period of dramatic biologic and climatic change led to a broader awareness of impacts as a. fundamental geologic process, a fact already documented on the other planets. Further analyses raised the possibility for a nonrandom and perhaps even periodic flux of bodies affecting the inner solar system, a problem that can be uniquely addressed from future lunar studies.

Third, the timely convergence of lunar studies enabling. computer technology, and recognition of planet-scale collisions as possible events early in solar system history led to serious consideration of the Moon as a product of a catastrophic collision on Earth. Such a perspective now provides a new context for understanding lunar and perhaps early terrestrial history.

Finally; the discovery of a tenuous Na and K atmosphere around both the Moon and Mercury may provide a new means to investigate interactions of the surface with its environment (microimpacts), in addition to degassing from the interior. Such advances serve to underscore the progress in knowledge made possible by the continuity of a vital program of basic research.

What began as a philosophy of post-mission data analysis naturally evolved into inter-mission thematic analysis. This parallel approach of directly related mission definition and analysis and basic research has formed the foundation for posing testable questions, refining mission objectives, and revealing new or even unexpected directions. An integral part of this philosophy includes continuity of complementary studies and facilities.

Earth-based spectroscopic observations of the planets have provided significant information about planetary surface materials, while radar imaging of Venus has revealed important clues about the nature of its surface, providing baseline information for planning future missions.

Remote sensing of the planets will continue to be an important aspect of planetary studies. The capabilities of ground-based telescopes are rapidly improving. New long-term observatories in near-Earth orbit, such as the Hubble Space Telescope and the Space Infrared Telescope Facility, will allow higher resolution and sensitivity for remote planetary observatories. These improved remote sensing capabilities will provide a context for the space missions to the planets, as well as direct comparisons between simultaneous remote and local observations. The scientific return of the spacecraft activities will be enhanced by these concurrent observations from the ground or Earth orbit.

Laboratory analyses help to constrain interpretations or broaden understanding of complex phenomena. Such analyses cross a wide range of relevant problems, including remote sensing, impact cratering, shock physics, and surface-atmosphere interactions. Similarly, theoretical studies permit exploring at broad scales complex phenomena such as global climate models, celestial dynamics, and impact processes.

Analog planetary studies in terrestrial settings permit testing aspects of both the experimental and theoretical approaches. Moreover, they provide essential information for broad-scale geologic processes such as suboceanic volcanism and rifting. Finally, interdisciplinary themes and timely synergistic studies permit thoughtful study of new discoveries without the time-constrained analysis of missions.

Continuity in basic research not only helps to achieve one of NASAs most fundamental goals, but also establishes a healthy scientific climate for education of the next generation of planetary scientists. It is important that NASA maintain the appropriate balance between planetary missions and the supporting research and analysis that provide the basis for understanding new results and for training future researchers. COMPLEX therefore recommends that NASA support a vigorous program of data analysis, basic research, and scientific instrument development.