SOFIA flies off into the sunset

Last month, a unique flying observatory made its final flight:

NASA’s one-of-a-kind 747 SOFIA flying telescope flew its final mission on Sep 28, wrapping up a career revealing mysteries of the universe that will keep astronomers busy for years to come.

SOFIA (Stratospheric Observatory for Infrared Astronomy) was a unique airborne observatory operated by NASA in partnership with the German Aerospace Center (DLR). It was a Boeing 747SP aircraft modified to carry an embedded telescope, and was able to fly into the stratosphere at altitudes of up to 45,000 feet. That put the flying observatory above 99 percent of Earth’s infrared-blocking atmosphere, allowing astronomers to study space in ways not possible with ground-based telescopes.

Engineers modified a Boeing 747SP to carry the DLR’s 38,000-pound, 100-inch reflective telescope. They also developed a “garage door” on the plane that rolled up to let the telescope work, as the plane flies above clouds and water vapor. SOFIA was also equipped with interchangeable instruments, to help the telescope make the right type of observations for a given mission.

It was one of the largest open ports ever flown on an aircraft, and the largest certified to fly at all altitudes and speeds with the door open. Pilots couldn’t even feel when the door was open. The stability of the telescope itself was equivalent to keeping a laser pointer steady on a penny from 10 miles away.

SOFIA was fully operational for 8 years, and logged 732 nights of observing. It helped astronomers worldwide study a wide range of cosmic events and objects invisible to other telescopes.

SOFIA was based out of Palmdale, California for most of the year, but would occasionally fly missions out of Christchurch, New Zealand to scan the skies over the southern hemisphere as well (here's a map of all 732 of its flights). The long-range, high-altitude 747SP, aircraft, previously in service with Pan Am and United, was ideally suited for this purpose.

NASA deemed the flying observatory as too expensive to operate past its 2021 fiscal year, which is why its mission ended at the end of September. It's a bit sad, but just another instance of the obsolescence of four-engined aircraft such as the 747SP. 

NASA inventories the ways in which "SOFIA changed our understanding of the universe," including the detection of the first type of molecule to ever form in the universe and insights into star formation.   accomplished by SOFIA during its mission. Sumeet Kulkarni details some of the instruments used and discoveries made by by the flying telescope. Simple Flying hopes the aircraft will end up at a museum once it is fully decommissioned; the National Air and Space Museum's Udvar-Hazy complex at Dulles Airport outside of Washington, DC and Space Center Houston are possibilities.