The Stratospheric Observatory for Infrared Astronomy (SOFIA) airborne observatory has begun making observations. Mounted in the back of a modified
747 Jumbojet, SOFIA is an infrared telescope of 100" aperture, and able to fly above 99% of the moisture in the Earth's atmosphere. This allows it
to obtain research grade pictures at less cost than launching a similarly capable space based telescope like the Spitzer (IR) or Hubble
For comparison, Spitzers mirror is .85meters in diameter, and the telescopes total cost was about 720 million dollars. The Hubble Space Telescope
(HST) has a 2.4m primary mirror, along with a corrector plate. It is an expensive Ritchie-Cretien (spelling?) type of Cassigerian telescope, and
cost around 1.5 Billion dollars, before all the servicing missions and the new mirror. BTW, that cost estimate is just that, and estimate, and was
the lowest I found. I also saw one up to 2.5 Billion. SOFIA has a 2.5m primary mirror and the system cost about 650 million dollars.
The advantages of SOFIA over an orbiting observatory is that, it lands. It can be upgraded and serviced without the cost of a shuttle mission. Which
soon of course will be impossible anyways since the shuttle is retiring.
Flying at the planned observational altitude of 41,000 feet, SOFIA will be able to get 80% the resolution of a space telescope of the same size.
SOFIA is not the first aerial telescope, first there was the Convair (Galileo) and Lear Jet Observatory, then the Kuiper observatory, mounted inside a
C141. More info, Flying Telescopes PDF
BTW, SOFIA missions are expected to run 8 hours/mission, 3 missions/week for 40 weeks/year, for 20 years.
Note that SOFIA take IR pictures, and IRs wavelength is some 37 times longer than the visual, so the IR pictures will be 37 times less resolution than
the equivilent size visual telescopes,
More info SOFIA Science Center
[edit on 3-6-2010 by JJRichey]