A Case Study in NASA-DoD - The Black Vault

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GFSC revealed that their analysis of the spacecraft heat balance, using
louvers rather than heaters and radiators, indicated it is more economical
to use louvers. The propulsion module for the MMS spacecraft (either
SPS-I or SPS-II) is mounted at the base of the spacecraft structure
and is thermally isolated from the structure and modules. A small
quantity of heat is transferred at the interface between the structure
and propulsion module and is accounted for in the thermal control
analysis of the entire spacecraft. As noted previously the STPSS
spacecraft uses a solid propellant rocket motor for propulsion and
must be thermally isolated from the modules with high temperature
multilayer insulation to prevent excessive heat transfer into the
modules during and after firing.
The design objectives for both spacecraft, from a thermal control
point of view, are generally the same, namely, thermally isolate each
individual module from the environment and other parts of the spacecraft.
The same basic design philosophy of using low-cost, proven
elements for the thermal control subsystem appears to apply to the
MMS and the STPSS. Thermal control elements for the MMS can be considered
as at least state of the art if not off-the-shelf.