Explorer 8

Launch data: Designation 00060 / 1960 Xi1 / 60014A Launch date 03 Nov 1960 - 05:23:10 UT Launch site CC, LC26B Launch vehicle  Juno 2 (#AM-19D) Mission Scientific: ionosphere study Earth orbit on Nov 03, 1960 (.3): Perigee / Apogee  417 x 2288 km Eccentricity  0.121 Inclination  49.95 deg Period  112.69 min Earth orbit on May 29, 2000 (.21): Perigee / Apogee  387 x 1156 km Eccentricity  0.054 Inclination  49.91° Period  100.27 min

Photo NASA

Description:

• Explorer 8 was a 41 kg mercury-battery-powered, earth-orbiting satellite designed to obtain measurements of the electron density, the electron temperature, the ion concentration, the ion mass, the micrometeorite distribution, and the micrometeorite mass in the ionosphere at altitudes between 400 and 1600 km. It was intended to study the temporal and spatial distribution of these properties and their variation from full sunlit conditions to full shadow, or nighttime, conditions.
• The payload was in the form of two truncated cones with the bases attached to a cylindrical equator. The outer shell was aluminum and had a diameter of 76 cm and a height of 76 cm. The 108.00 MHz transmitter had 100 mW average power, and it functioned for the life of the battery pack (54 days). The data system included telemetry consisting of continuous operation with real-time transmission.
• To avoid the possibility of effects on the experiments by asymmetrical charging on solar cell surfaces, solar cells were not used.
• Experiment instrumentation included an RF impedance probe, an ion current monitor, a retarding potential probe, a two-element and a three-element electron temperature probe, an electron current monitor, a photomultiplier-type and a microphone-type micrometeorite detector, an electric field meter, a solar horizon sensor, and thermistor temperature probes. Simultaneous measurements of electron and ion concentration were used to resolve the question of neutrality of the medium.

Mission details:

• Battery power failed on December 27, 1960 (just after 54 days). Considerable difficulty was encountered with decommutating the telemetered data to make machine processing possible. As a result of these difficulties, the data were mostly processed by hand. In spite of these difficulties, considerable new knowledge about the ionosphere was gained from operation of the satellite.
• During its mission, Explorer 8 confirmed the existence of a helium layer in the upper atmosphere. Explorer 8 answered many questions about Earth’s Ionosphere that were fundamental at the time.