Van Allen radiation belt
The objectives of the flight were to measure the Earth's magnetic field, the solar X-ray radiation and its effects on the Earth's atmosphere, the near-Earth micrometeoroid environment, and the drag effects and density of the upper atmosphere. Instrumentation included a proton magnetometer, X-ray ionization chambers, radio transmitters, and various micrometeoroid detectors. The data obtained provided a comprehensive survey of the Earth's magnetic field over the area covered, defined the lower edge of the Van Allen radiation belt, and provided a count of micrometeoroid impacts. Vanguard 3 has an expected orbital lifetime of roughly 300 years from launch.