SOFIA Telescope Primary Mirror Removed in Preparation for Coating

Photos below

April 18, 2008

Technicians at the NASA Dryden Aircraft Operations Facility in Palmdale, Calif., cautiously and meticulously removed the German-built primary mirror assembly from the Stratospheric Observatory for Infrared Astronomy, or SOFIA, April 18 in preparation for the final finish coating of the mirror. 

Under the watchful eyes of engineers and observers, technicians employed a high-precision crane and other equipment to lift the more than two-ton mirror assembly from its cavity in the rear fuselage of the highly modified Boeing 747SP aircraft. After it was safely removed, the assembly was gently secured in its cradle and moved to a clean room where it is being prepared for shipment to NASA Ames Research Center at Moffett Field near Mountain View, Calif. The assembly is scheduled to be airlifted to NASA Ames on an Air Force C-17 transport plane on
May 1.

Once at Ames, the one-of-a-kind 2.7-meter diameter mirror will receive its final aluminized finish coating in a zero-pressure coating facility, a process expected to take about three months. While it is out of the aircraft, engineers and technicians at Palmdale will be performing a variety of developmental tasks on the flying observatory, including re-routing of auxiliary power unit ducting, modifying the cavity door control system, installation of the Cavity Door Drive System actuators, replacement of the telescope's roller bearings, mounting non-reflective insulation inside the telescope cavity, installation of various mission sub-systems and making other mechanical refinements. 

"The removal of the mirror is the key to completion of the remainder of the integration work," said John Carter, SOFIA aircraft platform project manager at NASA Dryden.

When final coating is complete, SOFIA's primary mirror will be returned to the NASA Dryden facility in Palmdale and be reinstalled in the aircraft, with that operation presently scheduled for mid-August 2008. 

Once the integration work is complete and the mirror reinstalled, SOFIA will then undergo several months of systems checkouts and a combined systems test. That will lead to the second phase of flight tests, with the telescope cavity door being incrementally opened at various altitudes to determine the aero-acoustic effects or buffeting on the aircraft and telescope systems at various altitudes.

SOFIA is being developed jointly by NASA and the German Aerospace Center (DLR) as a world-class observatory, complementing the visible-range Hubble Space Telescope and other future ground and space-based infrared telescopes. Once operational, SOFIA will be the world's primary infrared observatory during a mission lasting up to 20 years, as well as an outstanding laboratory for developing and testing instrumentation and detector technology.

Systems integration and flight test operations are being conducted by NASA's Dryden Flight Research Center at the Dryden Aircraft Operations Facility in Palmdale, Calif. SOFIA's science and mission operations are managed jointly by the Universities Space Research Association (USRA) and the Deutsches SOFIA Institut (DSI), and are based at NASA's Ames Research Center at Moffett Field near San Jose, Calif.

The SOFIA primary mirror assembly is cautiously lifted from its cavity in the modified 747 by a crane in preparation for finish coating operations at NASA Ames. (Tony Landis / NASA)	Technicians with ropes carefully guide the primary mirror assembly as a crane slowly moves it toward its transport cradle after removal from the SOFIA aircraft. (Tony Landis / NASA)
Technicians position the transport cradle as a crane lowers SOFIA's primary mirror assembly into place prior to finish coating of the mirror at NASA Ames. (Tony Landis / NASA)	SOFIA's primary mirror assembly is cradled on its dolly as technicians prepare to move it into a "clean room" at NASA Dryden's Aircraft Operations Facility. (Tony Landis / NASA)
Technicians carefully guide SOFIA's primary mirror assembly on its transport cradle into a clean room where it is being prepared for shipment to NASA Ames. (Tony Landis / NASA)