Space telescopes don’t have to squint through the obscuring layer of Earth’s atmosphere, but ground-based telescopes have the distinct advantage of being easily accessed for repairs and tweaks. What lies between them? It’s a bird! It’s a plane! It’s a bird-plane! (Now you have that song in your head. You’re welcome.) No, it’s actually SOFIA, the plane-mounted telescope with a remarkable history. NASA’s Ames Research Center just posted this video walkthrough of SOFIA’s insides.
Originally designed as a Boeing 747SP widebody, the SOFIA aircraft was built on a modified 747 airframe with a stripped-down fuselage, to save weight on the ultra-long flights for which it was developed. While it flies as SOFIA for NASA under the call sign NASA747, originally the aircraft first flew regular passenger service with Pan Am. Pan Am actually invited Anne Morrow Lindbergh, Charles Lindbergh’s widow, to christen the aircraft “Clipper Lindbergh” in 1977, on the 50th anniversary of Lucky Lindy’s historic flight. At NASA’s invitation, Erik Lindbergh — grandson of Charles — re-christened it “Clipper Lindbergh” in 2007.
It looks like the telescope is moving, but really the plane moves around the telescope. The telescope stays still!
The 2.5-meter telescope itself sits inside an airlock bulkhead that can open while at cruising altitude, by way of a special Raytheon-designed door in the plane’s aft left side. This gives the telescope an unobstructed view of the skies, without sucking everyone out à la the terrible movie of your choice. It’s gyro-stabilized, which keeps the telescope’s eye fixed stably on its target, while the observing end of the telescope — and its operator — gets to stay safely inside the pressurized cabin. Mission control and scientific ops are in the middle, and there’s even a public outreach and education area up where first class would be.
The 747SP’s long-haul design concept is a major asset to SOFIA’s function as a flying observatory. Up above 99% of the water vapor in the atmosphere, the telescope can fly all night to stay in the best place to look at any given thing in the sky, including and especially the aurora borealis. Launching satellites is risky and dearly expensive, but avgas is apparently still cheap enough to keep SOFIA flying for the nonce.
SOFIA has been in the news in the not-too-long-ago. Nichelle Nichols, who played Lt. Uhura on the original Star Trek, took a 10-hour overnight observatory flight with SOFIA in late 2015, to spend telescope time watching multiple star-forming regions and a protostar in Taurus, while training several educators. The observant reader may notice in the image below that Lt. Uhura was apparently accompanied by several Tribbles, which leaves some question as to the ultimate fate of the aircraft. Evidently they are not as extinct as we were led to believe.