Left panel: the SPAN-A composite instrument, consisting of two ESA instruments, SPAN-I and SPAN-Ae. The sensor on the left is the SPAN-Ae electron sensor, and the sensor to the right is the SPAN-I instrument. The deflectors, the polished gold-colored surfaces in the analyzer heads, are clearly visible in the image. Right panel: the SPAN-B instrument, mounted to a thick aluminum plate (non-flight). SPAN-B was designed to be safe to operate when in sunlight, and part of that design includes the use of radiator fins on top of the analyzer (shown) and a radiator plate under the electronics box (obscured in figure) on in combination with AZ-2000-IECW, which functions as a radiative coating.