The SR-71 Blackbird provided a reconnaissance platform that was unmatched. It would have been pretty high in the sensitivity list when it came to its sensors and capabilities. Now the jets are all retired. The example that is in the Evergreen Aerospace Museum has one of the sensors extracted from the sensor bay and mounted on a stand in front of the aircraft. I imagine there was a time when this was something that would not be available for me to look at but now, I guess, this is just another obsolete piece of tech.