Instruments I: Wave Experiment Consortium

The control and computing brain for the WEC. It provided precise timing that allowed correlation studies between the four spacecraft, and had a particle correlator that enabled variations in the electron population around the spacecraft to be compared with the wave measurements.

EFW used electrical sensors on four 42-metre-long wire booms to measure electric fields and waves. Currents generated in each sensor revealed the density of nearby electrons. EFW could take up to 36 000 measurements per second, allowing the motion of plasma structures and wave fronts travelling at thousands of kilometres per second to be detected.

A magnetometer that picked up any rapid variations in the magnetic field the spacecraft happened to be passing through. This occurred particularly in regions where the charged particles of the solar wind interacted with the magnetosphere.

WBD was designed to provide high-resolution measurements of both electric and magnetic fields in selected frequency bands. WBD listened for radio whistles and hisses from particles that bounced around near Earth's magnetic poles.

WHISPER used radar to measure the density of charged particles in space. Brief radio pulses, sent out through the two 42-metre-long EFW wire booms, triggered oscillations or 'echoes', which were detected after a short delay. In addition, WHISPER monitored natural wave activity in the frequency range 2–80 kHz.