Circumferential heat pipes can be used to conduct heat to full circumference of the spacecraft. The ACS power load can be very high to counter aero-torques. Whether reaction wheels or momentum wheels are used they are likely to be torqued at high powers during perigee passage and, until the speed can be reduced by momentum unloading later in the orbit, they will continue to require relatively high power. Duty cycling of the instruments is the only option. The exact amount of duty cycling required depending on many factors including b angle, CP-CG offset, power system efficiency, and natural instrument duty cycle.
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The solar arrays spin the wheels up during the sunlit period and the wheels generate electricity during eclipses. How to minimize, and control, the CP and CG locations provide one of the major trades for the spacecraft design. Kinetic theory has to be modified by an accommodation coefficient. Experimental data from AE-C indicates that models based on kinetic theory and ground measure accommodations coefficients results in overly conservative thermal design. A tungsten resistance thermometer on the ram surface of AE-C measured temperatures no higher than 150 C at 135km.