Introduction to the Report on Geodesy

The following articles summarize the achievements of the U.S. geodetic community during the years 1971–1974, between the General Assemblies of the IUGG. During this quadrennium, American geodesy made the first transition from meeting the traditional needs of surveying and mapping to catering to the geophysical and oceanographic communities, trying to satisfy their ever‐increasing appetite for ultraprecise surveys. Major achievements included the completion of the National Geodetic Satellite Program, probably the largest single effort to establish a global network of satellite tracking stations and the determination of the earth's gravity field to an accuracy heretofore not available; the proliferation of Doppler satellite observations for control surveys and polar motion determination; the affirmation of lunar and satellite laser ranging and very long base line interferometry (VLBI) as the best available geodetic tools for global geophysical investigations, such as plate tectonics, polar motion, and the earth's rotation; the development of the satellite‐borne altimeter and the establishment of its feasibility for a better definition of the surface of the oceans; major improvements in the knowledge of the dynamics, size, shape, gravity field, and topography of the moon and some of the major planets; the extension of the high‐precision transcontinental traverse to a total of 9000 km, only 10% of the network remaining for completion in 1975; the start of the readjustment of the North American Datum, in collaboration with Canada, Mexico, and Denmark; and an unprecedented cross‐fertilization between geodesy, solid earth geophysics, oceanography, and dynamical astronomy.