The EESA instrument consists of two sensors: EESA-i (right side of image below) measures suprathermal ion flows, while EESA-e (left side) measures suprathermal electrons and magnetic topology.

Suprathermal Ions
(UCB/SSL: R. Livi)

Energy: 0.5 eV -30 keV (17% ΔE/E)
Angles: 2.8π(23°x23°)
Mass: M ≤ 4, M ≥ 16

Suprathermal Electrons
(UCB/SSL: P. Whittlesey)

Energy: 10 eV -10 keV (17% ΔE/E)
Pitch Angle Distributions: 20-160°(23°x23°)