SOFIA was the latest, probably the last airborne observatory. I just heard about SOFIA a couple of years ago and now – SOFIA is done.
SOFIA (Stratospheric Observatory For Infrared Astronomy) was the best of the airborne observatories. Armed with leading edge technology, this observatory’s promise was to produce groundbreaking data.
Conceived of in 1984, NASA first proposed they and German Space Agency DLR (Deutsches Zentrum für Luft- und Raumfahrt) team up (80% NASA, 20% DLR) to create SOFIA starting with a highly modified Boeing 747 SP aircraft. Due to Germany’s reunification and budget changes at NASA the project did not start until 1996.
SOFIA was to have the largest airborne observatory telescope yet, with a 2.5 – meter (100”) diameter mirror, made in Germany. The mirror is a lightweight honeycomb design, using Schott Glass’s new Zerodur glass/ceramic substrate with nearly zero expansion, so it was not affected by dynamic ambient temperatures. The telescope is configured as a Cassegrain reflector with a f1.3 parabolic primary and remotely adjustable hyperbolic secondary, giving a final focal ratio of f19.7. A flat dichroic coated tertiary mirror sends infrared light to the Nasmyth focus for evaluation.
Guess what? More delays. In 2001 three subcontractors went out of business and United Airlines pulled out of the project as the plane’s operator – it entered bankruptcy litigation. SOFIA did finally get finished and test flights commenced in 2007.
SOFIA’s instrument capabilities included mid-to-far infrared imaging, spectrographic and visible light imaging, and a new instrument – the HAWC+ (High-resolution Airborne Wide-band Camera Plus) to produce data for spectacular images of large-scale magnetic fields.
SOFIA’s primary missions included examining our solar system planet’s atmospheres and surface structures, cometary structure and composition, analyze interstellar medium, and observe stellar and planetary system formation. Some of SOFIA’s accomplishments include examining Pluto’s exceedingly thin atmosphere, discovering molecular oxygen in Mars’ atmosphere, detecting water on the sunlit portion of the Moon, and observing the occultation of a star by Kuiper Belt object 486958 Arrokoth – in preparation for the New Horizons spacecraft visit. Its HAWC+ camera system has produced mesmerizing images of how magnetic fields around galaxies are warped by interactions with other galaxies.
SOFIA was also part of NASA’s public outreach with its Airborne Astronomy Ambassadors Program, partnering with educators from K-12, science museum and planetarium educators.
During SOFIA’s earlier lifetime it had a controversial reputation for excessive costs to run it, around $85 million per year while not producing the amount of data anticipated. In later years new management of SOFIA’s projects doubled its output but that did not sway decision makers as they cut funding and cancelled SOFIA.
SOFIA saw first light on May 26, 2010 and last light on September 29, 2022. It currently resides at the Pima Air & Space Museum in Tucson, AZ.
What’s in the Sky?
March 20; 4:24 pm CDT: Vernal Equinox – spring!
March 22; 45 minutes after sunset; west: Jupiter and a crescent Moon are low and close – use binoculars.
March 25; 8:30 pm: Astronomy Night at Tye Preston Memorial Library in Canyon Lake.