work in 1998, Raytheon designed and installed a tall (arc length) by wide door in the aft left side of the aircraft's fuselage that can be opened in-flight to give the telescope access to the sky. The telescope was mounted in the aft end of the fuselage behind a pressurized bulkhead. The telescope's focal point is located at a science instruments suite in the pressurized, center section of the fuselage, requiring part of the telescope to pass through the pressure bulkhead. In the center of the aircraft was the mission control and science operations section, while the forward section hosts the education and public outreach area. The open fuselage has no significant influence on the aerodynamics and flight qualities of the airplane. At NASA's invitation, Lindbergh's grandson, Erik Lindbergh, re-christened the aircraft as Clipper Lindbergh, on May 21, 2007, the 80th anniversary of the completion of Charles Lindbergh's trans-Atlantic flight. During December 2012 the aircraft received a glass cockpit flight-deck upgrade along with new avionics systems and software updates. On April 28, 2022, the Project announced it was retiring the aircraft as of September 30, 2022. Its 921st and last mission was over the North Pacific Ocean off the coast of California, taking off from Palmdale Regional Airport (ICAO KPMD) and landing there 7 hours and 57 minutes later at 04:41 PDT (11:41 UTC). Project development The first use of an aircraft for performing infrared observations was in 1965 when Gerard P. Kuiper used a NASA Convair 990 to study Venus. Three years later, Frank Low used the Ames Learjet for observations of Jupiter and nebulae. In 1969, planning began for mounting a telescope on an airborne platform. The goal was to perform astronomy from the stratosphere, where there was a much lower optical depth from water-vapor-absorbed infrared radiation. This project, named the Kuiper Airborne Observatory, was dedicated on May 21, 1975. The telescope was instrumental in numerous scientific studies, including the discovery of the ring system around the planet Uranus. The proposal for a larger aircraft-mounted telescope was officially presented in 1984 and called for a Boeing 747 to carry a three-meter telescope. The preliminary system concept was published in 1987 in a Red Book. It was agreed that Germany would contribute 20% of the total cost and provide the telescope. However, the reunification of Germany and budget cuts at NASA led to a five-year slide in the project.