Abstract: A horizon sensor for spaced-based satellites consisting of a high critical temperature superconductor which changes temperature based upon its exposure to space-based radiation. The horizon sensor may be flexibly positioned along the outer surface of the space- based satellite. As the orientation in space of the satellite varies, certain portions of the satellite body will be alternately exposed to radiation while other portions of the satellite body will be shadowed from it. As the sensor is exposed to radiation due to the change in orientation of the satellite body, the temperature of the superconductor changes due to radiation absorption. This change in temperature causes the conductivity of the superconductor within the sensor to vary, and this causes a change in voltage within the sensor. This voltage may be appropriately processed via land based or satellite based control systems to accurately measure and/or change the orientation of the satellite in space.