The former Pan Am Clipper Lindbergh 747SP is being converted into a giant flying telescope platform in Palmdale, CA, and Waco, TX. It is carrying a 2.5 meter diameter, 20-ton Nasmyth reflector telescope that will be capable of imaging primarily in the infrared portion of the electromagnetic spectrum, as well as in the visible portion, for secondary tasks. The aircraft will fly 8 ~ 10 hour missions an average of three times a week through about the year 2030 (including down-time for maintenance/upgrades, relocation, etc.). The telescope has been installed and will perform observations through a 16 foot high, by 10 foot wide, opening in the upper left fuselage, just forward of the horizontal and vertical stabilizers. The aircraft has completed closed-door test flights with very favorable results, and will be undergoing eight months of computer, communications, and telescope instrument equipment installation and minor airframe modifications in Palmdale, CA, at the former Rockwell International / North American Aircraft B-1B Production Plant 40, adjacent to U.S. Air Force Plant 42, and its two 12,000-foot runways. In the Fall of 2008, SOFIA will begin a series of about 12 open-door flight tests to ensure that the aircraft can fly safely with the doors open various amounts, over a range of airspeeds and altitudes from about 38,000 to 45,000 feet MSL. By the Spring of 2009, SOFIA will begin limited "early science" missions while additional flight and systems tests are completed, and will begin full scientific missions in 2010. Instrument development will continue through at least 2014, when at least 20 different instrument packages will be available, with at least six installed aboard the aircraft on any given flight (instruments will be able to be installed and removed in a few hours between flights, as needed). The telescope is mounted in an oil-filled spherical bearing that allows it to roll from 15 to 75 degrees above the horizon, and three degrees fore-and-aft from the aircraft centerline, so that it is effectively decoupled from aircraft movements in calm to mildly-turbulent air. It will be able to remain bore-sighted on an astronomical target with an angle the size of a dime at a distance of over ten miles.
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Even after three hours, the line of visitors snaked from the Moffett Federal Airfield operations building, unabated from earlier in the afternoon, until well after evening civil twilight (aka "dark" to non-aviators) - IMG_0318
The empennage ("tail feathers") of the SOFIA aircraft - being able to wander around a 747 on the tarmac is not something I've gotten to do before (the Transportation Security Agency really gets upset if you try that at an airport, especially since 9/11!) - definitely something every aviation buff should put on their "bucket list" - IMG_0316
Another view of the telescope cavity outer door - it can't be opened on the ground, or in flight, because the drive system components haven't been installed, yet - that will be done during the equipment installation period that will occur from late January through September 2008, at the SOFIA aircraft servicing facility in Palmdale, in a 200,000+ square foot hangar at what used to be the North American Aircraft Plant 42, adjacent to the U.S. Air Force's Plant 40, and two 12,000-foot runways - IMG_0315
Close-up view of the telescope cavity outer door, which measures about 10 feet wide by 16 feet high - this allows the telescope to roll between 15 and 75 degrees around the aircraft's centerline - there is also an inner aperture door that limits the exposure of the telescope to air moving past at up to Mach 0.92 at altitudes between - IMG_0314
Side view of the amazing 747SP main landing gear truck - smaller aircraft pilots, who pass beneath a 747 with its landing gear extended, call it a "Goodyear overcast" because of the huge amount of rubber that's going by - a 747 with its gear retracted is just a "Boeing overcast" - IMG_0313
747SP main landing gear are an impressive feat of engineering, even if they weren't attached to an aircraft, and capable of holding up close to 700,000 pounds of aircraft, including 40,000 pounds of telescope assembly, and about 300,000 pounds of fuel - IMG_0310
SOFIA at dusk, with ground power equipment connected to power the aircraft lighting, air handling, and telescope assembly control equipment during the tours - IMG_0309
The SOFIA aircraft cockpit - pretty much your standard, run-of-the-mill, 747SP instrument panel, flight controls, and sheepskin-covered pilots' and flight engineers' seats (747s are pretty much the only passenger airline aircraft that still have flight engineers' consoles, as newer aircraft have much more computer automation of the engine control systems) - IMG_0308
FAA Airworthiness Certificate (don't leave the tarmac without it!) that took over 10 years to obtain, due to the extreme modifications made to the airframe - cutting a 10-foot wide by 16-foot high hole in an aircraft, among many other not-quite-so-extreme modifications, will make that more difficult than for the standard model! - IMG_0307
View of the port (left) T.U.R.D. rack with an instrumentation server and hard drive, but, with the control laptop computer removed, which is mounted in the rack slides above the server - IMG_0306
The Testing Universal Rack Device (T.U.R.D.) - no kidding, zoom in to see the acronym label in the upper right corner of the orange rack - this is one, of two, racks, that hold the in-flight testing equipment used to monitor and record aerodynamic control inputs and corresponding aircraft responses and performance - IMG_0304
View from the upper deck down into the aft portion of the operations and control area on the main deck (this would normally not be possible in a stock 747SP!) - IMG_0300
The telescope assembly control system software user interface, running on a laptop computer here until the full system is installed in the aircraft - this translates operator inputs for aiming the telescope, and allows the control system to be monitored as it maintains telescope bore-sighting on an astronomical target - IMG_0299
View of the Mother of All Junction Boxes, mounted overhead, above the telescope assembly, through which 28 VDC, 115 VAC, and fiber optic data lines are routed - note the cables passing through the aft pressure bulkhead into the telescope cavity, where the telescope 2.5 meter diameter parabolic primary, 0.5 meter hyperbolic secondary, and two 0.2 meter wide tertiary infrared and visible light mirrors are located within their support frame - IMG_0299
Another close-up of the telescope control circuitry that ensures the telescope assembly is isolated from aircraft movements, up to +/- 3 degrees in yaw and pitch, sufficient to correct for mild turbulence at cruise altitudes between 38,000 and 45,000 feet above Mean Sea Level (MSL)