Remote Sensing Satellites Conceptual Design Figure 8. f/H for available sizes of detector elements and the boundary values of f/H based on the constraint of the orbit altitude. Figure 9. The allowable design area after sizing to the spatial resolution. According to Figure 8, the value of f/H for the detector elements larger than 2 μm are greater than the boundary values specified in Figure 8 and they are outside of the allowable area, so only the sensor with size 2 μm remains in the allowable area and the four other sensors with size larger than 2 μm will be unusable. Due to the lenses manufacturing technological constraint, the value of the DD, f/D is enclosed between two boundary values of 1.2 and 2.8 then allowable area in this stage is as indicated in Figure 9. 2. Sizing to the Spectral Resolution Requirements. The following equation, which relates the physical properties of an optical satellite image payload, can be considered: 46 D= λf (8) Qx Equation (8) could be rewritten as follows: f Q.x = λ D (9) When the smallest pixel size is taken into account, then: f λ f x .Q ≥ xmin ≥ min DQ D λ When the largest pixel size is taken into account, then: x ≥ xmin = 2 μ m x ≤ xmax = 14 μ m IEEE A&E SYSTEMS MAGAZINE f λ f x .Q ≤ xmax ≤ max DQ D λ FEBRUARY 2018