subcontracted to the European industry. The telescope was German-made; the primary mirror was cast by Schott AG in Mainz, Germany with lightweight improvements, with grinding and polishing completed by the French company SAGEM-REOSC. The secondary silicon carbide-based mirror mechanism was manufactured by the Swiss Center for Electronics and Microtechnology (CSEM). A reflective surface was applied to the mirror at a facility in Louisiana but the consortium now maintains a mirror coating facility in Moffett Field, allowing for fast recoating of the primary mirror, a process that was expected to be required 1–2 times per year. The SOFIA aircraft The SOFIA aircraft was a modified Boeing 747SP widebody (serial number 21441, line number 306; registration N747NA; callsign NASA747). Boeing developed the SP or "Special Performance" version of the 747 for ultra long range flights, modifying the design of the 747-100 by removing sections of the fuselage and heavily modifying others to reduce weight, thus allowing the 747SP to fly higher, faster and farther non-stop than any other 747 model of the time. Boeing assigned serial number 21441 (line number 306) to the airframe that would eventually become SOFIA. The first flight of this aircraft was on April 25, 1977, and Boeing delivered the aircraft to Pan American World Airways on May 6, 1977. The aircraft received its first aircraft registration, N536PA and Pan American placed the aircraft into commercial passenger service. Shortly thereafter, Pan Am named this aircraft in honor of aviator Charles Lindbergh. At the invitation of Pan Am, Lindbergh's widow, Anne, christened the aircraft Clipper Lindbergh on May 20, 1977, the 50th anniversary of the beginning of her husband's historic flight from New York to Paris in 1927. United Airlines purchased the plane on February 13, 1986, and the aircraft received a new aircraft registration, N145UA. The aircraft remained in service until December, 1995, when United Airlines placed the aircraft in storage near Las Vegas. On April 30, 1997, the Universities Space Research Association (USRA) purchased the aircraft for use as an airborne observatory. On October 27, 1997, NASA purchased the aircraft from USRA. NASA conducted a series of "baseline" flight tests that year, prior to any heavy modification of the aircraft by E-Systems (later Raytheon Intelligence and Information Systems then L-3 Communications Integrated Systems of Waco, Texas). To ensure successful modification, Raytheon purchased a section from another 747SP, registration number N141UA, to use as a full-size mock-up. Commencing