Explorer 7 was a NASA satellite launched on 13 October 1959, at 15:30:04 GMT, by a Juno II launch vehicle from Cape Canaveral Air Force Station (CCAFS) to an orbit of and inclination of 50.27°. It was designed to measure solar X-ray and Lyman-alpha flux, trapped energetic particles, and heavy primary cosmic rays. Secondary objectives included collecting data on micrometeoroid penetration, molecular sputtering and studying the Earth-atmosphere heat balance. Satellite description The spin-stabilized satellite's external structure consisted of two truncated conical fiberglass shells joined by a cylindrical aluminum center section. The spacecraft was wide at its equator and about high with a payload mass of about . The spacecraft was powered by approximately 3000 solar cells mounted on both the upper and lower shells. Additional power was provided by 15 rechargeable nickel-cadmium batteries that were positioned on its equator near the outer skin as an aid in maintaining a proper spin rate. Two crossed dipole (1 W, 20-MHz) telemetry antennas projected outward from the center section, and a 108-MHz antenna used for tracking was mounted on the bottom of the lower shell. Located around the periphery of the center section were five bolometers for thermal radiation measurements and three cadmium sulfide micrometeoroid detector cells. A cylindrical ion chamber (lithium fluoride window) and a beryllium window X-ray chamber were located on opposite sides of the upper cone, and a cosmic-ray Geiger counter was located on the very top. A primary cosmic-ray ionization chamber was located within the center portion of the upper cone. Communications and tracking were provided by a 108-MHz transmitter at 15-mW designed to operate for 2 months and a 20-MHz transmitter at 600-mW powered by the solar cells designed for cut-off after about one year. Experiments Ground Based Ionospheric An all-transistor beacon telemetry transmitter was operated at a fundamental frequency of 19.9915 MHz. This transmitter, which was powered by solar cells and rechargeable nickel-cadmium batteries, provided 660-mW of power at the fundamental frequency. It also radiated the second and third harmonics (15-mW each) at 39.9830 and 59.9745-MHz. Beacon receivers were known to have been located in Washington, D.C., and Chicago, Illinois. Interpretation of the changes of beacon signal characteristics between the satellite and the ground station showed irregularities to be present at all times of the day with horizontal dimensions of to . Data were received over a period of 16 months. Heavy Primary Cosmic Rays This experiment