Thermal Control Subsystem (TCS)

The TCS guarantees - by passive and semiactive control - the temperature ranges and gradients required to enable the Science Instruments and Spacecraft equipment to perform their functions and operations.

The passive control is performed using standard thermal control components:

Multilayered insulation

to decouple the Satellite inner side thermally from deep space and from the sun input effects.

Radiation panels

to reject the interior generated heat dissipation.
Rigid Second Surface Mirrors (SSM) are glued on the honeycomb panels external skins to provide the required thermo-optical properties (emissivity 0.80, absorptivity 0.17 at End of Life).

Surface coating

to control the radiative heat exchange inside the Satellite and to minimize the temperature gradients, surface coating is used applying, extensively, black paint and, locally, aluminized tape.

Thermal filler

interposed between equipment mounting feet/baseplate and the mounting structure to increase the the thermal conductance.

Thermal screens

consisting of Kapton foil that, ensuring X-ray transparency, are interposed in the detectors field of view to provide protection against sun impingement and to reduce cooling effects due to direct space exposure.

Thermal baffles

consisting of Aluminum frames from the sensors and Detectors up to the Satellite external walls, that provide either a shadow effect or a barrier against sun impingement.

The TCU is an internal redundant unit that, on the basis of temperature measurement from the thermistors, performs on/off switching of the heaters in accordance with predefined and programmable temperature thresholds.

The Thermal Control design is substantially driven by the temperature ranges and gradients imposed by the Science Instrument.

In particular because of its criticality, a development test has been performed to verify the local design (thermal baffle and heaters lay-out) for C/S Mirror Unit control.

This file was last modified on Wednesday, 02-Sep-1998 17:28:58 CEST by Mauro Orlandini