[2] It was intended to study the temporal and spatial distribution 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 km (250 mi) and 1,600 km (990 mi) and their variation from full sunlit conditions to full shadow, or nighttime, conditions.

The addition of a single grounded grid and a positively biased collector permitted the measurement of electron current as a function of satellite attitude.

The experiment also allowed the grid to be swept from -1.2 to +8 V in order to measure the spacecraft equilibrium potential and the external electron temperature.

One probe, with the inner grid at -15 V, collected incoming positive ions while repelling external electrons and suppressing internal photoelectrons.

Some manual recognition of meaningful signal sequences was systematized, and a limited amount of this information formed the total observational data obtained from the experiment.

For the first mode, an aperture grid was maintained at spacecraft potential to monitor the orientation sensitivity of electron diffusion current.

Another severe limitation to the collection of useful data was the failure of the commutation system to provide information in a machine-sensible form.

[6] Two piezoelectric crystals, each attached to two sounding boards acoustically isolated from the satellite skin, were used to measure the frequency and momentum of micrometeorite impact.

Information from these sensors was obtained in low-, medium-, and high-sensitivity levels and stored in three independent digital counters.

The maximum sensitivity of the sensor to light pulses was of the order of 1.E-14 erg, which means it could detect impacts of particles of 1.E-14 g having a velocity of 20 km/s.

[9] Because of its symmetrical shape, Explorer 8 was selected for use in determining upper atmospheric densities as a function of altitude, latitude, season, and solar activity.

Density values near perigee were deduced from sequential observations of the spacecraft position, using optical (Baker-Nunn camera network) and radio and/or radar tracking techniques.

[11] A replica is on display at the Smithsonian National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Virginia.