At 48 years old, Boeing 747 is getting long in tooth. (For an aircraft, that is.) But over the years it’s proved itself to be one of the most versatile aircraft. Its upstairs deck has been home to swinging champagne bars. Its wide belly has made it a favorite of cargo transporters. Modified 747s serve as mobile command centers---heard of Air Force One? But NASA’s really taken it to extremes: It's transported space shuttles strapped to one, and cut a gigantic hole in the side of another, for stargazing.
Since 2010, that hole has allowed scientists to point an on-board 8.2 feet telescope towards the cosmos, while pilots take the plane well above any water vapor in the Earth’s atmosphere. The Stratospheric Observatory for Infrared Astronomy, SOFIA, rivals the Hubble Space Telescope in size, and researchers have used it to study the atmosphere of other planets, the fields of gas where stars are born, and the composition of comets.
Telescopes need to be aimed precisely, so building one into a plane, and making it turbulence proof, took some major engineering. NASA started with a 747SP, or Special Performance, which is lighter than a regular jumbo, and can fly higher and farther. (The plane previously saw service with United and Pan Am as a regular passenger jet.) The space agency worked with Raytheon to cut open a 16-foot by 23-foot section of fuselage, behind the wing, and cover it with a sliding door. They performed extensive tests to make sure the gaping hole didn’t make the plane unflyable.
The telescope itself is mounted on fast reacting gyroscopes to keep it locked on a target, even if the flight gets bumpy. As you’ll see in our clamber-around (above) the interior of the plane is mostly given over to racks of equipment and seats for researchers to watch their data come in. But most impressive of all is the sheer scale of the telescope, and the venerable plane that carries it. As members of the flying public we're more likely to be squished into uncomfortable seats than staring into black holes, so we don’t often get to see just how big---and multitalented---a jumbo jet really is.
