History of SOFIA and Airborne Astronomy

This article by Wendy Whiting Dolci from a 1997 issue of the American Institute of Aeronautics and Astronautics' magazine is a history of airborne astronomy platforms starting in the 1920s and continuing to SOFIA's predecessor the Kuiper Airborne Observatory (KAO) that ended service in 1996. Wendy was one of the KAO's on-board Mission Directors and later Assistant Project Manager.

History of SOFIA and Airborne Astronomy
November SOFIA target of opportunity flight – Comet ISON
FIFI-LS instrument delivered to SOFIA operating base
July SOFIA deploys to Southern Hemisphere
April SOFIA observes G35 star forming region
SOFIA makes 100th science flight
October First detection in the interstellar medium of the mercapto radical SH and the deuterated hydroxyl radical OD
August SOFIA Observes Sharpless 140 Star-forming region
April SOFIA instrument upgrades announced
March SOFIA images Planetary Nebula M2-9
January Twenty-Six educators selected to fly on SOFIA
SOFIA images newborn star cluster W3A
December SOFIA examines Messier 42 (M42)
November SOFIA studies W40 Star Forming Region
SOFIA observes Betelgeuse
September SOFIA’s first Trans-Atlantic Deployment (Cologne and Stuttgart, Germany)
June SOFIA observes Pluto Occultation
April First flight of SOFIA’s GREAT instrument
January SOFIA images Messier 42 (M42)
November SOFIA begins "Short Science" observing phase with FORCAST and the German REceiver for Astronomy at Terahertz Frequencies, or GREAT. (GREAT's flights began in April 2011.) First science flight flown on November 30, 2010, with FORCAST on the telescope.
May "First Light" for SOFIA achieved on the night of May 25/26. Targets are Jupiter and Messier 82 galaxy.
February The Faint Object InfraRed Camera for the SOFIA Telescope, or FORCAST, instrument is delivered to the NASA Dryden Aircraft Operations Facility (DAOF) in Palmdale, Calif.
December SOFIA achieves first 100-percent open door test flight.
June The Science Vision for SOFIA is published. Download the pdf (22 MB file).
October Primary Mirror reinstalled into SOFIA.
June Primary Mirror coated for first time at NASA Ames Research Center.
April Telescope Primary Mirror removed in preparation for coating
March SOFIA Line Operations conducted in Palmdale, CA at the Dryden Aircraft Operations Facility. A team of scientists, engineers, and staff from ARC, DFRC, USRA, DSI, DLR, and MAN collaborated on a series of tests of the SOFIA telescope assembly and software
January SOFIA Visits Ames Research Center on the way to its permanent home at the SOFIA Operations Center, located at the Dryden Aircraft Operations Facility (DAOF) in Palmdale, CA.

SOFIA’s 747 flown to Dryden Flight Research Center, at Edward AFB in California for systems installation and integration and additional flight testing

SOFIA Re-Dedicated as "Clipper Lindbergh" at Dryden Flight Research Center

April SOFIA Completes First Flight in Waco, TX
August NASA PMC (Program Management Council) chooses Dryden Flight Research Center to complete systems installation and integration and conduct flight tests of the flying observatory; SOFIA Program Office responsibility relocated to DFRC. Under new Program structure DFRC has responsibility for the "Platform Project" (e.g., the aircraft), and ARC has responsibility for "Science Project".
July FORCAST Instrument tested at Palomar.
(on-going) Fuel tanks Checked
April-May Installation of Lower Flex Door and Aperture Assembly
February Landing Gear Checked
January Installation of Upper Rigid Door
December Installation of Upper Rigid Door
September-November Three external reviews: Independent Science & Operations Review (ISOR), budget/management review (ICSMR), Independent Aircraft Operations Panel (IAOP)
August HIPO successfully installed on telescope mount
June Partnership with Evergreen
April Proof Pressure Test

SOFIA Telescope Floats!

TA activated for course drive movements

Science Instrument Mounting Flange and TA Balancing Assembly mounted to Suspension Assembly

Secondary Mirror and Spider Vanes attached to Metering Structure

TA Metering Structure installed in aircraft

Telescope Suspension Assembly installed in aircraft

Aircraft downjacked onto landing gear


All skins mounted on aircraft

Modified aircraft structure completed

Cavity Bulkheads completed

All components of Cavity Door in fabrication

CDR of Data Archive System successfully completed

Mirror Coating facility in SSMOC tested and working

FLITECAM (SOFIA Science Instrument) has successful "first light" at Lick Observatory

Telescope arrived in Waco from Germany


AIRES instrument cancelled

Mounting of skins on aircraft proceeding

HAWC Critical Design Review (CDR) completed


SOFIA CDR successfully completed

Incremental telescope CDRs completed

Telescope cradle completed

Completion of Software Final Design Review

Incremental Integration of USRA/DARA telescope software in Munich

First cut of airplane cavity skin

Forward bulkhead floor assembly completed

Cavity aft bulkhead installed

Aircraft stringer and reinforcements installed

Cavity sill beams modified

Galley CDR completed

Aircraft ceiling raised for telescope assembly

MCS Build 2 completed

Conceptual Design Review for SAFIRE completed

Data Cycle Core System demonstrated at Rochester Institute Of Technology


Flight Scheduler Preliminary Design Review (PDR) completed

EPO presents IR Airborne Teacher's Workshop in Phoenix

SIRTF/SIM/Astrobiology EPO collaboration launched

Science Observing Scenarios briefed to Steering Committee

First metal (structural member) cut on aircraft

Telescope assembly CDRs completed

SOFIA "4 Minute Features" to be shown on United Airlines in-flight News videos


Four calibrated test flights with maneuvers give confidence to flight stability load distribution, and pressure responses

Design efforts continue for modified aircraft structures and subsystems

Telescope Assembly Incremental Design Reviews begin

Telescope Assembly Mock-up installed

Mission Control System Build 1 completed

Mirror-coating contract awarded

Hanger N211 extensively modified — demolition and steel fabrication, roof

Airplane water, oxygen, air conditioning systems modified

Internal shoring installed on aircraft from mock-up Section 46

Telescope Assemble CDRs begin

Science Observing Scenarios working group meets

Final design of observatory Layout of Personnel Accomodations (LOPA) submitted

Aircraft Mass Simulator designed

Liquid nitrogen injection system designed

EPO airborne astronomy presentations in Idaho, Michigan, California


SOFIA PDR completed

Design efforts under way for modified aircraft structures and subsystems


Data Archive and Data Cycle Group formed

Ames Work Products development begins (Water Vapor Monitor, Flight Scheduler)

Airplane cavity Environment Control System (ECS) designed

Rerouting of air, etc. within aircraft

Designed observatory Power Distribution System

Design work on the LOPA (floor plan) begins

Air Worthiness Manual preparations begin

Instrument Rotator designed


SOFIA dedication ceremony held at NASA Ames

Call for Proposals goes out to the observing community

First Light Instruments selected

US Peer Review of First Light Instrument proposals

Telescope Readiness Review completed

SOFIA (Readiness Review) (SRR) completed

SOFIA website released



ARC gets new Center Director


SOFIA Project Management gives briefing to NASA HQ Programs Management Council.; ARC Space Projects Review Board given SOFIA presentation


U.S. SOFIA RFP released


NASA DARA management interface meetings held in Germany and in the U.S.; Proposals received from U.S. industry teams.


DARA receives proposals for TA.


DARA and DLR merger begins.


DARA down-selects SOFIA TA Contractor team. MAN/K-T/MAN consortium awarded fixed priced contract for development of TA.


USRA team awarded SOFIA contract for aircraft purchase, modification, and system integration.



February SOFIA III wind tunnel test completed.


Non-Advocate Review held at ARC; Industry Briefing on SOFIA Privatization held at ARC.


Interface meeting with DARA and German teams held at ARC.


DARA Interim Phase B Study contracts completed by two teams: MAN/K-T and Zeiss/Dornier.


Science Symposium in Switzerland discusses SOFIA.


Stand-down of KAO; ÒLive from the StratosphereÓ last flight; Boeing 747SP course given at ARC by United Airlines.


SOFIA IV wind tunnel test completed; SOFIA Industry Workshop held in Sunnyvale, CA.


NASA and DARA both working on their respective RFP drafts.



NASA and DARA continuing to work together in attempts to get SOFIA moving forward on both sides of the Atlantic; Science Working Groups in Germany and in the US busy advocating SOFIA.


SOFIA II wind tunnel test for aft configuration completed.


DARA Phase B1 Studies performed by two German teams.



Briefings held for various center management review panels on new SOFIA implementation plan, with FY94 "in-house" option proposed APRIL Efforts under way to prepare for aft configuration wind tunnel test


In-house approach approved by Office of Space Sciences (OSS) at Headquarters, by ARC New Business Filter Committee, and by SOFIA In-house Implementation Plan review committee

Headquarters Code C funding augmentation executed for technology development work


ARC Code R agrees to de-mothball 14 ft wind tunnel for SOFIA test; Test entry planned for 1994

CFD model on full -SP finalized for first test run

Began locating a section 46 of a Boeing 747

"Pro-Engineer" selected as Project and Code E computer-aided design (CAD) package


Headquarters OSS proposes recycling SOFIA as an FY95 new start to Administration/Comptroller


German Space Agency indicates willingness to participate in SOFIA with an FY96 start


NASA redirects planning for an FY96 start with DARA participating



IR measurements made of the Shuttle Carrier Aircraft (SCA) engine plumes using IR cameras mounted in Lear jet


Kickoff meetings for Telescope NRA studies (Lockheed Missiles & Space Company (LMSC), Hughes, Kaman)


Kickoff meetings for Aircraft NRA studies (E-Systems and Lockheed Aircraft Services, Ontario)


Second flight test on IR plume noise is made with cameras mounted inside SCA


Further options investigated to reduce total project costs, including initiation of in-house approach study


Plume study completed; aft installation feasibility verified and baseline change confirmed


Final reports of Aircraft System NRA submitted; Results concur with Ames in-house study regarding feasibility and cost savings for the aft cavity configuration

Feasibility of modifying existing SOFIA wind tunnel model for an aft cavity investigated

In-house implementation plan study fully underway; telescope, consoles + electronics, part of aircraft mod brought in-house to ARC



NAS Decade Survey (Bahcall committee) Report recommends SOFIA as the top priority moderate new mission for NASA


DARA's budget uncertain

Second wind tunnel entry planned for January 1992 to refine door design trade space


Development on three cavity door configurations for the wind tunnel model underway at ARC


With the realization of possible DARA budget cuts, SOFIA plans for FY92 start with an all U.S. program, with optional help from DARA in FY94 MAY Aircraft Modification Contractors road trip: Find out what companies have interest/capability to perform the SOFIA aircraft modification


Cavity Cooling System in-house study report finished


In-house descope studies begin, to try to reduce total SOFIA cost; 5 cases considered: 1 thru 4 are telescope cost reduction options/case 5 considers an aft cavity location to reduce aircraft modification costs


NASA Research Announcement (NRA) planned as procurement method to fund multiple studies with U.S. contractors to develop a U.S. option for the telescope

Descope studies completed; Only case 5, reducing the aircraft modification cost by about 40%, which in turn reduces the total cost of the project by 12%, appears to be viable approach, since the science impact is moderate.

Planned January 1992 wind tunnel test indefinitely postponed because of new, aft configuration selected for further study

NRA planned for two aircraft studies to confirm the feasibility and in-house estimate of savings for aft installation


Computational Fluid Dynamics (CFD) studies on aft cavity are initiated

NRA released for Telescope System studies

Aft installation studies begin to analyze background IR noise caused by engine exhaust plume

Aft cavity location adopted as new baseline for the Aircraft System, pending study results


NRA released for Aircraft System study



SOFIA wind tunnel model tests start


Shear layer control device is developed for wind tunnel model


German Space Agency, DARA (Deutsche Agentur fuer Raumfahartangelegenheiten) budget cuts begin


Non-Advocate Review is held for SOFIA in accordance with the agency's new start-gate policy; SOFIA deemed ready to proceed to development again and recommended for 1992 start

Preliminary engineering study of SOFIA Ground Support Facility at new site underway

Aircraft System modification procurement activities underway, Source Evaluation Board (S.E.B.) established


Wind tunnel tests successfully completed; A low drag passive shear layer control device derived, that exceeds performance expectations

Redefining of cavity door begins, to incorporate wind tunnel test results

In-house studies of Telescope Sub-Systems begin


Consoles and Electronics System (CES) mock-ups evaluated

Reunification of Germany, requiring reduction of German government agencies' budgets



Telescope diameter fixed at 2.5 meters by NASA HQ/DFVLR agreement


Wind tunnel model design complete and fabrication begins


Headquarters establishes Science Working Group (SWG) as follow- on to SOFIA Science Consulting Group

Recommendation to proceed with development from Space Science and Applications Advisory Committee (SSAAC)

Project Definition Review completed at ARC; Found SOFIA well planned and defined and approved the project to proceed into the development phase contingent on a successful completion of wind tunnel test


Draft MOU for development and operations phases reviewed by Ames, headquarters (Code S, X, and G), SWG, and the German Aerospace Research Establishment (DLR), formerly DFVLRFabrication of wind tunnel model completed by Microcraft; Model air-freighted to Ames. However, SOFIA wind tunnel test start delayed to allow completion of incumbent test


Non-Advocate Cost Review successfully completed at ARC with NASA Headquarters participation; Affirmation of project readiness for 1991 start; FRG listed as responsible for telescope assembly

14 ft wind tunnel breaks down: cracked turning vanes, SOFIA test start delayed further

Definition studies completed by NASA and BMFT; Phase B complete


Telescope and Aircraft System Phase B final reviews are completed and reports published


Boeing re-organizes; No longer interested in "one-of" mods like SOFIA


Berlin wall falls; Reunification of East and West Germany considered



Small IR Project Concept Review awards SOFIA highest priority, Committee on Space Astronomy (CSAA) and Astrophysics endorses SOFIA


Phase B Aircraft Proposal review at Boeing Military Airplanes (BMA)


SOFIA in preliminary Office of Space Science and Applications (OSSA) Research and Analysis FY90 budget for start of development and acquisition of aircraft


Space and Earth Sciences Advisory Committee (SESAC) recommends that SOFIA proceed into definition phase

Rose Engineering under contract to provide wind tunnel test plan and be the principal investigator in defining the SOFIA cavity shear layer control device


Meetings at Society of Photo-optical Instrumentation Engineers (SPIE) and ARC with FRG (Zeiss) technical experts on technology status, study issues, interfaces, and planning

Microcraft begins conceptual design of wind tunnel model at 7% scale

Project Readiness Review (PRR) of SOFIA at ARC; Approval to proceed with project definition


SOFIA zeroed for new start in FY90 budget; Replanning for FY91 development starts

Requirements and interfaces documents for definition studies completed and distributed

Resource assessment studies completed with Electrospace Systems Inc. (ESI), E-Systems, and The Analytical Sciences Corporation (TASC)


Phase B (Definition Study) kickoff meeting for German Telescope Assembly at Zeiss completed

Data System definition study kickoff at ARC by Code EES

Ames project coordination meeting completed with DFVLR in Cologne

Preliminary Design Review of wind tunnel model completed

BMFT (Bundesministerium fuer Forschung und Technologie), the German Ministry of Science and Technology, issued authority to proceed with Phase B definition studies for Telescope System


Project Readiness Review of Telescope System completed at Zeiss

Interface definition meeting between three German telescope contractors, BMA, and Ames completed at Zeiss


Astrophysics division/BMFT workshop completed at NASA Headquarters



Telescope System Phase A Study midterm review at ARC


Boeing-MAC Phase II Study


German Phase A studies complete


SOFIA concept review held at ARC


Science Applications International Corporation (SAIC) cost study for Aircraft System


Ames Conceptual System study finished; SOFIA "Phase A System Concept Description" (The Red Book) published



Ames Research Center (ARC) establishes SOFIA Study Office


SOFIA technology workshop at Ames; Informal examination of the SOFIA concept and associated technical issues presented by experts in the related disciplines


Boeing-MAC Phase I Study; Confirms the feasibility of installing a 2.5 meter telescope in a 747SP JULY Ames receives draft of the Memorandum of Understanding (MOU) for Telescope System study Statement of Work (SOW) from Germany


A presentation of SOFIA is held at NASA Headquarters


Ames in-house Conceptual System study begins


Collaborative agreement made with DFVLR (Deutsche Forschungsanstalt fuer Luft und Raumfahrt), the German Aerospace Research Establishment
German Phase A Telescope System studies kickoff

1985- 1965


NASA Headquarters allocates FY86 funding for Aircraft Modification Study; Science Consulting Group formed; NASA headquarters (HQ), Ames Research, and Federal Republic of Germany (FRG) representatives meet at HQ and Germans agree to study the development of the Telescope System


Ad hoc advocacy group of IR astronomers formed for LAT; Paper on LAT presented; "Stratospheric Observatory For Infrared Astronomy (SOFIA) Preliminary Feasibility Study" report issued in December; Ames/Astronomical Society of the Pacific (ASP) Symposium: Airborne Astronomy (10th KAO Anniversary)


Success of Infrared Astronomy Satellite (IRAS) shows need for follow-up/exploitation


International Astronomical Union (IAU) Symposium : IR Astronomy; Invited discussions of KAO and LAT


Concept summary for LAT developed by KAO staff; "Three Meter Telescope on a 747SP Platform" paper presented


Boeing delivered to NASA Ames a study for a LAT in a Boeing 747SP


Planning for LAT continued at low level


First research flight of KAO; Initial studies on larger system


Development well underway on the 36-inch telescope now to be mounted in a Lockheed C-141 platform; Project named the Kuiper Airborne Observatory (KAO); Greenstein report on "Large Stratospheric Telescope" published


Planning started for installation of 36-inch telescope in a CV-990; First astronomy community interest in Boeing 747 1971 National Academy of Sciences (NAS) Decade Survey (Greenstein) Report recommended study of Large Airborne Telescope (LAT)


First use of NASA aircraft for infrared (IR) astronomy (Convair CV-990 and Lear Jet)

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