The Stratospheric Observatory for Infrared Astronomy (SOFIA) was a 2.7 meter telescope (with an effective aperture of 2.5 m) carried aboard a Boeing 747SP aircraft. It was the successor to the smaller Kuiper Airborne Observatory (KAO), which was operated by NASA.
SOFIA was a joint project of NASA and the Deutsches Zentrum für Luft- und Raumfahrt (DLR, the German Space Agency). Flight operations were conducted out of the NASA Armstrong Flight Research Center in Palmdale, California. The SOFIA Science Center (SSC), responsible for overseeing the scientific output of the mission, is located at the NASA Ames Research Center in Moffett Field, California. The Science Mission Operations were jointly managed by the Universities Space Research Association (USRA) for NASA and by the Deutsches SOFIA Institut (DSI), in Stuttgart, for DLR. Aircraft operations were handled by NASA Armstrong.
The observing altitudes of SOFIA were between 37,000 and 45,000 feet, above 99% of the water vapor in the Earth's atmosphere. The telescope and instruments provided imaging and spectroscopic capabilities in the 0.3-1600 µm wavelength range. The telescope was located in an open cavity in the rear section of the aircraft, with a view out of the port side. Observations were done at elevations between +20 and +60 degrees. The telescope was inertially stabilized and the pointing accuracy was about 0.5 arcseconds.
At the end of 2022, SOFIA had 6 instruments, both imagers and spectrographs, covering a wide range in wavelength and spectral resolution. These included five Facility Science Instruments (FSIs), EXES, FORCAST, FIFI-LS, FPI+, and HAWC+, which were maintained and operated by Science Mission Operations (SMO), and one Principal Investigator-class Science Instrument (PSI), GREAT, maintained by the instrument team. FSIs and PSIs were available to all General Investigators. Additionally, SOFIA carried a Water Vapor Monitor, which was used to measure the precipitable water vapor level along a fixed line of sight. The resulting values were used to calibrate the data obtained using the science.
The U.S. share of the overall observing time was 80%. This US time was awarded based on peer review of proposals submitted in response to periodic proposal calls. The calls were open to both the US and international astronomical communities. The remaining 20% of the time was allocated to the German astronomical community. Observing on SOFIA was done in service, or queue, mode and it was not required that General Investigators be present on the aircraft while their observations were being obtained.
SOFIA offered astronomers a unique platform, providing regular access to the entire mid-infrared/far-infrared wavelength range. With a wide range of instruments, SOFIA complemented ground based facilities such as Keck, Gemini, JCMT and ALMA as well as current and future space-based IR missions (Spitzer, Herschel, JWST). The capabilities of SOFIA and its potential are described in several Design Reference Mission case studies and in the "Science Vision" document, which are listed below.
SOFIA Science Traceability Matrix
Matrix showing some of SOFIA's main areas of scientific contributions, linking the strengths of SOFIA to one third of the Astro2020 Decadal report scientific priorities. (2022)
SOFIA vs. JWST: What's the Difference?
Infographic showing how SOFIA and JWST complement each other (2022)
SOFIA Science: Remarkable Results
Brochure highlighting some of SOFIA's significant discoveries (2021)
Overview of EXES science (2020)
Overview of FIFI-LS science (2020)
FORCAST Highlights as of 2020
Presentation with overview of FORCAST science. (2020)
Overview of GREAT science (2020)
Science with SOFIA
Comprehensive presentation about SOFIA and SOFIA science, Bernhard Schulz (2020)
Overview with examples of SOFIA science. (2020)
Far-Infrared studies of Galaxy Evolution
Astro2020 Science White Paper (2019)
Presentations from "The Local Truth: Star-Formation and Feedback in the SOFIA Era -- Celebrating 50 Years of Airborne Astronomy"
Presentation files from conference held in October 2016
"The Case for SOFIA"
This overview is designed to provide a broad‐brush rationale for the case for SOFIA, designed for an interested non-technical audience. (2014)
"The Science Vision for the Stratospheric Observatory For Infrared Astronomy"
This document presents the overall vision for the mission and highlights key science questions that will be addressed by SOFIA.
"Training of Instrumentalists and Development of New Technologies on SOFIA", a white paper by Erickson et al. (2009).
Science Cases (Design Reference Mission Case Studies)
Water in Space: Comets and the Interstellar Medium
(Bergin, Blake, Goldsmith, Harris, Melnick, Zmuidzinas; 2008)
Supernova Remnants and the Life Cycle of Interstellar Dust
(Dwek, Arendt, Bregman, Colgan, Dinerstein, Gehrz, Moseley; 2008)
Exploring the early Evolution of our Solar System using SOFIA
(Sitko, Russell, Lynch, Wooden, Lisse, Woodward, Kelley; 2008)
Protostellar Cores in Infrared Dark Clouds
(Staguhn, Jackson, Rathborne, Simon, Wyrowski, Benford; 2008)
Deep HAWC Surveys for Far-IR Luminous Galaxies
(Blain, Davidson, Moseley; 2005)
New Insights into the Physics of Infrared Cirrus
(Dowell, Hildebrand, Lazarian, Werner, Zweibel; 2005)
Precise Photometry of Extrasolar Planets
(Dunham, Brown, Charbonneau, Elliot, McLean; 2005)
Exploring the Kuiper Belt with Stellar Occultations
(Elliot and Dunham; 2005)
The Interstellar Deuterium Abundance
(Guesten and the GREAT Consortium; 2005)
Spatially Resolved Protostars in Taurus
(Hillenbrand and Eisner; 2005)
The Protostellar Luminosity Function
(Hillenbrand, Greene, Harvey; 2005)
Methane in Mars' Atmosphere: Evidence for Life or Uncertain Detections?
(Lacy, Richter, Greathouse; 2005)
SOFIA Observations of the Circumnuclear Disk at the Galactic Center
(Morris, Erickson, Chuss, Stacey, Staguhn; 2005)
Magnetic Fields, Turbulence, and Star Formation
(Novak, Davidson, Dowell, Hildebrand, Kirby, Lazarian, Looney, Zweibel; 2005)