The Magsat project was a joint NASA/United States Geological Survey (USGS) effort to measure near-earth magnetic fields on a global basis. Objectives included obtaining an accurate description of the earth's magnetic field, obtaining data for use in the update and refinement of world and regional magnetic charts, compilation of a global crustal magnetic anomaly map, and interpretation of that map in terms of geologic/geophysical models of the earth's crust. The spacecraft was launched into a low, near-polar, orbit by the Scout vehicle. The basic spacecraft was made up of two distinct parts: the instrument module that contained a vector and a scalar magnetometer and their unique supporting gear; and the base module that contained the necessary data-handling, power, communications, command, and attitude-control subsystems to support the instrument module. The base module complete with its subsystems was comprised of residual Small Astronomy Satellite (SAS-C) hardware. The magnetometers were deployed after launch to a position 6 m behind the spacecraft. At this distance, the influence of magnetic materials from the instrument and base module (chiefly from the star cameras) was less than 1 nT. Sixteen complete vector magnetic field measurements and eight scalar measurements were obtained every second.