Explorer 61 (Magsat-A)

The Magsat project was a joint NASA/United States Geological Survey (USGS) effort to measure near-earth magnetic fields on a global basis. It was the third of a series of Applications Explorer Missions (AEM). 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.