SOFIA. NASA public domain image colelction.

ED09-0279-14 This close-up of the German-built telescope assembly seen through the open telescope cavity door in the side of NASA's SOFIA 747SP offers a view of both the primary and secondary mirrors, the latter a small black circle in the center supported by three braces. At the bottom of the opening is the white lower flexible door at its lowest retraction. The dark semi-circle on the right is the telescope aperture that follows the telescope in elevation as the assembly moves. The orange wiring is platform instrumentation and will aid in the analysis of the aircraft's flight performance with the upper rigid door
both open and closed. September 24, 2009 NASA Photo / Tom Tschida
NASA Identifier: 392095main_ED09-0279-14_full