Importance

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Abstract

A spacecraft (10) has an attitude sensor (20) mounted on its body (12). The sensor must be maintained near a temperature setpoint. Each sensor (20) produces its own temperature-indicative signal. Each attitude sensor is coupled to a thermally conductive instrument platform (18). A standoff (21) supports the platform (18) away from a baseplate (16) and the spacecraft body (12). The standoff (21) includes a thermally conductive portion (22) adjacent the platform (18), and a nonconductive portion (24) remote from the platform. An electric heater (26) is connected to the thermally conductive portion (22) of the standoff (21). A temperature sensor (28) thermally coupled to the platform (18) generates platform temperature signals. A filter (212) high-pass filters either the platform temperature signals or the attitude sensor temperature signals, to form filtered signals. A combining circuit (218) combines the filtered signals with the other temperature signals, to make composite temperature signals. A difference arrangement (224) coupled to the setpoint source (226) and to the combining circuit (218) generates error signals by subtracting composite temperature signals from setpoint signals. A PI processor (232) generates heater drive signals by summing proportional and integral signals. A driver (232) drives the heater (26) in response to the heater drive signals. When plural attitude sensors are mounted on the platform, the attitude sensor temperatures are averaged before further processing. The filter (212) may have a cutoff frequency which is the reciprocal of the thermal delay between the heater (26) and the attitude sensors (20), and may have a low-pass noise characteristic.

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