Does these aircraft have FLIR (foward looking infared)? If so, this aircraft could be looking for hot spots?
Funny you mentioned it. I just looked and they do (all upgrades including fiber optic wiring.
>https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104560/u-2stu-2s/
The U2 aircraft has the following sensor packages: electro-optical infrared camera, optical bar camera, advanced synthetic aperture radar, signals intelligence, and network-centric communication.
Roger that , excellent point.