The payload is extremely simple with only two single pixel sensors and a single Combined Electronics Unit (CEU). The IBEX payload and spacecraft achieve the simplest, most flexible, most reliable, and lowest risk design with very ample margins within the constraints of the SMEX program. The overlap between IBEX Hi and Lo maximizes statistics and allows for in-flight cross-calibration, and provides imaging via two completely independent sensors across the most critical energy range for achieving the IBEX science objective.