Stratospheric Observatory for Infrared Astronomy—or SOFIA to its friends—is actually a laboratory with wings used by both NASA and the German Aerospace Center, DLR. And right now, it's getting its decadal inspection at the Lufthansa Technik hangar in Hamburg.
SOFIA's actually a heavily modified Boeing 747 Special Performance jetliner, that flies 39,000 to 45,000 feet in the air to record infrared spectrum that's otherwise blocked by water vapour in the Earth's atmosphere. Up there, it can study celestial objects at wavelengths that just can't be observed from ground-based observatories.
But, like any plane, it needs more maintenance than a simple Earth-based observatory. So, it sits in Germany, being tended to by science personnel from the Armstrong Flight Research Center and Lufthansa's 747 specialists. Together, they'll keep it air-worthy and scientifically accurate. [NASA]