The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce Alberts is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce Alberts and Dr. Robert M. White are chairman and vice-chairman, respectively, of the National Research Council.

The Committee on Geodesy (COG) of the National Research Council (NRC) has long been involved in evaluating the opportunities for new insights and applications that accurate geodetic measurements offer the earth, ocean, and space science communities. With the development of the Global Positioning System (GPS) and the possibility of having very precise aircraft navigation, new scientific opportunities exist for high-resolution surveys of the topography and gravity field of the Earth. To assess these new opportunities and the ways in which airborne techniques using GPS might complement other ground-and space-based techniques, COG held a workshop on airborne geophysics in July 1993. The goals of the workshop were as follows:

• to evaluate the current status of airborne geophysics and precise positioning techniques;
• to identify the scientific objectives that are made possible by integrating aerial measurements and precise positioning techniques; and
• to propose strategies for expanding and optimizing the future development of airborne research platforms, aircraft-based measurements, and precise positioning.

A steering committee of six individuals from COG with expertise in both the instrumentation and the scientific aspects of airborne geophysics planned the workshop. Steering committee members were Robin Bell (chair), Thomas Herring, Christopher Jekeli, J. Bernard Minster, Richard Sailor, and David Sandwell. Held on July 12–14, 1993, in Washington,

D.C., the workshop consisted of plenary and poster sessions that allowed interaction between federal managers and the applied and basic research communities.¹ Workshop participants (see Appendix D) included approximately 40 scientists and engineers who are active in the areas of airborne geophysics and precise positioning, or who are addressing research questions that could benefit from the application of a new generation of airborne geophysical measurements.

The workshop (see the agenda in Appendix C) was organized around four principal technical elements of airborne geophysical measurements and the scientific objectives that can be addressed by these new techniques. The themes of the workshop were as follows:

The scientific objectives of the next generation of airborne geophysics programs were discussed within the framework of the technical elements. Working groups chaired by members of the steering committee developed conclusions related to these themes. The major conclusions of the working groups are presented in Appendix B.

The following report is based primarily on information presented at the workshop and on the expertise of the workshop participants and the steering committee. The Committee on Geodesy worked with the steering committee in the preparation of this report and takes full responsibility for its conclusions and recommendations.