BOEING 747SP (N747NA)

They opened the aircraft to allows folks to go inside for a look around and a quick briefing. The telescope has been removed, but you wouldn't be able to see it anyway because it was behind a pressure bulkhead. In any case, a very cool airplane.

More info from the PASM website:

"In 1997 the aircraft was bought by NASA for a joint project with the German Aerospace Center (DLR). The project named SOFIA, Stratospheric Observatory for Infrared Astronomy, was an airborne infrared observatory that could fly above 99 percent of the infrared blocking atmosphere.

"L-3 Communications in Waco, Texas was contracted to make the heavy modifications to the 747SP that were necessary to install a 20-ton, 8.9-foot-wide telescope and all the support equipment. SOFIA’s first flight was April 26, 2007, and was finally ready for full observations in 2014. Being a mobile observatory allowed SOFIA to conduct research from almost anywhere in the world. SOFIA flew around 100 flights a year primarily flying out Palmdale, California and Christchurch, New Zealand.

"In November 2021 it was decided to cancel the SOFIA program due to the high operating cost. On December 13, 2022, SOFIA flew from Palmdale to Davis Monthan Air Force Base in Tucson, AZ for display at the Pima Air & Space Museum."

See: https://pimaair.org/museum-aircraft/boeing-747sp/

See more about the Stratospheric Observatory For Infrared Astronomy aircraft here:

https://science.nasa.gov/mission/sofia/