Compensation of radiation towards outer space for horizon sensor thermopiles. Electronic circuit elements which form part of the device for controlling the compensating source are incorporated in a metallic material which consequently radiates to the thermopiles a thermal power which is proportional to the power which passes through these elements. Thus substantially all the power consumed is used in this source, so that the power consumption is reduced to a minimum. Applications for compensation of radiation towards outer space which gives rise to zero errors in the case of differences in sensitivity between the detectors in the attitude sensors.