Stable operation of the CCDs with low dark current
requires cooling the CCDs to a temperature of 
C.
Temperature variations during flight must be small to minimize changes
in the CCD performance.
The CCDs are cooled by a Marlow Industries thermoelectric
cooler (TEC).
Heat from the TEC will
be dumped to the top plate of the experiment (on the anti-solar side) for
radiation to space.
The TEC voltage is set by serial command (SC38), and will be
maintained near the top of the allowed range to provide the maximum
cooling to the CCD.
We expect the CCD to operate at a temperature of about 
C in flight.
(Several serial commands exist that were intended to enable
temperature control of the CCDs by a simple feedback
loop controlling the TEC supply voltage to maintain a fixed
CCD temperature. Due to time constraints, this mode was never
implemented.)