The main telescope consisted of five collinear elements (three solid state, one Caesium iodide (CsI), and one sapphire Cherenkov) surrounded by a plastic anticoincidence shield.

The instrument consisted of a stack of 11 fully depleted silicon solid-state detectors surrounded by a plastic scintillator anticoincidence cup.

[9] The instrument was designed to measure ambient electric fields in the solar wind and the Earth's magnetosheath up to 1 kHz in frequency.

The wires were insulated from the plasma, except for their short outer sections, to remove the active probe area from the spacecraft sheath.

However, the effective low-frequency filter threshold was determined by interference due to harmonics of the spacecraft spinning within an asymmetric sheath.

Whenever the electron plasma density was less than about 10 particles/cc, the sheath overlapped the active antenna portions and precluded meaningful measurements of ambient conditions.

The magnetic and electric field intensities and frequency spectra, polarization, and direction of arrival of naturally occurring radio noise in the magnetosphere were observed.

Phenomena studied were the time-space distribution, origin, propagation, dispersion, and other characteristics of radio noise occurring across and on either side of the magnetospheric boundary region.

The instrumentation consisted of a three-element telescope employing fully depleted surface-barrier solid-state detectors and a magnet to deflect electrons.

[12] This experiment consisted of a boom-mounted triaxial fluxgate magnetometer designed to study the interplanetary and geomagnetic tail magnetic fields.

With the aid of a bit compaction scheme (delta modulation), 25 vector measurements were made and telemetered per second.

[13] This experiment was designed to measure the energy spectra of low-energy electrons and protons in the geocentric range of 30 to 40 Earth radii to give further data on geomagnetic storms, aurora, tail and neutral sheet, and other magnetospheric phenomena.

[14] The Goddard Space Flight Center cosmic-ray experiment was designed to measure energy spectra, composition, and angular distributions of solar and galactic electrons, protons, and heavier nuclei up to Z=30.

The first system consisted of a pair of solid-state telescopes that measured integral fluxes of electrons above 150, 350 and 700 keV and of protons above 0.05, 0.15, 0.50, 0.70, 1.0, 1.2, 2.0, 2.5, 5.0, 15, and 25 MeV.

[15] A hemispherical electrostatic analyzer measured the directional intensity of positive ions and electrons in the solar wind, magnetosheath, and magnetotail.

Energy analysis was accomplished by charging the plates to known voltage levels and allowing them to discharge with known RC time constants.

[16] A modulated split-collector Faraday cup, perpendicular to the spacecraft spin axis, was used to study the directional intensity of positive ions and electrons in the solar wind, transition region, and magnetotail.

[17] This experiment was designed to determine the composition and energy spectra of low-energy particles observed during solar flares and 27-d recurrent events.

The detectors used included: (1) an electrostatic analyzer (to select particles of the desired energy per charge) combined with an array of windowless solid-state detectors (to measure the energy loss) and surrounded by an anticoincidence shield and (2) a thin-window proportional counter, solid-state particle telescope.