LM124s were not used since they are not available in surface-mount packages. The completed PC boards will be tested down to -60 degC to assure conformance with specifications. The AD538 has only been tested to 10 krad. It is unknown if it would pass at 100 krad. Aluminum and tantalum shielding will be added to the board to protect the two AD538s from radiation.
Heat can be a concern in space applications since there is no convection cooling.
Higher-dissipation components were connected to large copper foil areas to help radiate heat. The filters on the photodiode inputs each consist of a pair of ferrite beads in series and a 0.001 uF capacitor in shunt. It is unknown if these filters are needed or if they are adequate.