The Suprathermal Electron Telescope, STE, is a new Instrument designed to measure Electrons in the Energy Range ~2 keV to 20 keV which are present as a Superhalo on the Solar Wind Electrons, and as CME Shock-Accelerated, or Flare-Accelerated Populations extending beyond the SWEA Range. These Electrons are ideal for tracing Heliospheric magnetic Field Lines back to their Source Regions on the Sun and for determining Field Line Lengths, thus probing the Structure of Interplanetary Coronal Mass Ejections, ICMEs, and of the ambient Inner Heliosphere.

STE utilizes passively cooled Silicon Semiconductor Devices, SSDs, which measure all Energies simultaneously. The STE consists of two Arrays of four SSDs in a row, each ~0.1 cm^2 Area and ~500 microns thick. Each Array looks through a rectangular opening that provides a ~20°×80° Field of View for each SSD with the 80° direction perpendicular to the Ecliptic. Adjacent Fields of View are offset for a total Field of View of ~80°×80°. The two Arrays are mounted back-to-back, looking in opposite Directions, centered about 25°. from the average Parker Spiral Field Direction. STE is located just inboard of SWEA on the STEREO Boom to clear its Field of View and remain in shadow.