Date: November 6, 2009

Title: SOFIA – Flight Tests and the Promise of New Science


Podcaster: Martin Ratcliffe

Organization: SOFIA Science Center, NASA Ames Research Center

Description: SOFIA, the Stratospheric Observatory for Infrared Astronomy, is about to begin detailed flight testing, leading to its official “First Light” flight. SOFIA houses a 2.5-meter telescope in the tail of a converted 747-SP Jumbo Jet. Flying above 99% of atmospheric water vapor, the telescope will study a wide range of astronomical objects over its expected 20-year lifetime. Come on board and tour this amazing aircraft and learn about some of the astronomical targets as the aircraft approaches its first open door flights this spring, followed by its first science observations this summer.

Bio: Nicholas A. Veronico, SOFIA Science Center Public Affairs Officer Veronico holds a journalism and a business management degree, and is the author or co-author of more than 25 books on aviation, military, and local history subjects.

(Dr.) Dana E. Backman, SOFIA Outreach manager Backman was a professor of physics and astronomy for 12 years at Franklin and Marshall College in Lancaster, Pennsylvania. Since 2003, Backman has been employed by the SETI Institute as manager of Outreach programs at the SOFIA Science Center.

Martin Ratcliffe is Director of Professional Development for Sky-Skan, Inc, a leading digital planetarium manufacturer. Martin is a contributing editor for Astronomy magazine, co-writing the Sky Show monthly column for the past 13 years. Martin has published 4 books, including Cosmology and the Evolution of the Universe (Greenwood Books, 2009), The Night Sky Revealed (Barnes and Noble, 2007) and State of the Universe 2008 and 2009 (Praxis-Springer).

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Palomar Observatory, a world-class center of astronomical research that is owned and operated by the California Institute of Technology. Learn more at


SOFIA’s Flight Tests the New Astronomy


Earlier this year, I took you on a tour of the SOFIA observatory and its promise of upcoming flights. Now, with a script by Dr Dana Backman, SOFIA’s Outreach Manager and infrared astronomer, and his colleague, Nicolas Veronico, the SOFIA Science Center Public Affairs Office, we bring you an update on forthcoming flight tests, a behind the scenes look at what they involve, and a window on the exciting science that will come from SOFIA’s 20-year lifetime.

The world’s largest flying infrared telescope, the Stratospheric Observatory For Infrared Astronomy, or SOFIA, is about to enter its second phase of flight testing. This round of tests will culminate in the observatory’s “First Light” flight when SOFIA will make its inaugural celestial observations from altitude.

Developed as a joint venture with the German Space Agency, known as DLR, SOFIA is a highly modified Boeing 747SP fitted with a 2.5-meter (8.2-foot) infrared telescope in the former airliner’s aft fuselage.

While flying between 39,000 and 45,000 feet, SOFIA’s 17-ton telescope and instruments can collect energy at wavelengths ranging from 0.3 microns to 1,600 microns (that’s 1.6 mm to you and I), including the entire infrared band. Flying at these altitudes puts SOFIA above more than 99 percent of the Earth’s water vapor, which is important because large parts of the mid- and far-infrared spectrum are blocked by water vapor and inaccessible even to observatories on high mountain tops.

As the First Light flight approaches, four of SOFIA’s eventual eight specially constructed scientific instruments are ready for action. Six of the eight instruments are being built by U.S. teams and two are from German university teams.

SOFIA’s ability to study the cosmos from the stratosphere enables astronomers to study:

  • Other galaxies and the center of the Milky Way Galaxy
  • The interstellar medium, especially chemistry of compounds that are the building blocks of life
  • Formation of stars and planets, and
  • Comets, asteroids and other objects of interest in our solar system

SOFIA will fly approximately 120 science flights per year once in full operation. Not only that, classroom teachers can participate in the science process by flying on board the observatory as working partners with the astronomers.

Upcoming Flight Tests

The SOFIA program has two geographically separate operating bases working together to take advantage of infrastructure and staffing talents. The overall SOFIA program plus observatory development and aircraft operations are managed from NASA’s Dryden Aircraft Operations Facility at the Palmdale Airport in Southern California. Having the aircraft at a NASA Dryden operated facility enables the space agency to use its staff of aircraft experts to maintain and service the aircraft.

SOFIA’s scientific operations are conducted from NASA’s Ames Research Center in Mountain View, between San Francisco and San Jose, California. The SOFIA Science center is able to draw upon the science infrastructure, wind tunnels, supercomputers, and staffing pool at NASA Ames and the surrounding communities.

From both locations, NASA researchers are working to complete the pre-operation phase of SOFIA’s conversion from airliner to flying astronomical research laboratory. Final software checks and ground operation of the telescope are carried out while the last steps of platform and observatory development are accomplished. Everything from swinging the landing gear to setting the compass must be done before SOFIA can once again take flight.

To accomplish both the science and flight operations requires a staff of more than 450 people, each an expert in their respective areas.

As you listen to this report, aviation technicians are now sitting with astronomers to determine the best flight paths that will yield the longest observing times for specific astronomical objects. Other specialists are testing the telescope cavity door operation, and still others are installing computer hardware and software to record observing data.

While all of this is being accomplished, there is a team of aviation technical experts ensuring safety at all times.

When SOFIA returns to the sky for the first time, the flying observatory will be escorted by NASA F/A-18 chase aircraft to monitor the aircraft, assist the flight crew, and record the aircraft’s performance during the tests. Chase crews will relay information about the cavity door’s position and operation to enable the SOFIA crew to validate the readings of their instruments.

The upcoming series of flight tests will test the operation of all aircraft and telescope systems in stages. The aerodynamics of the telescope cavity will be tested by opening the door in increments –10 percent, then 30 percent, in a series of flights over several weeks, until the door is open 100 percent. At each stop, a series of flight maneuvers will be flown to validate the wind tunnel and supercomputer tests that predicted how airflow will interact with the telescope cavity. Once these tests are complete, they will be repeated, but this time the 17-ton telescope will be unlocked and allowed to swing freely.

The following series of flights will test the telescope’s star tracking capabilities and how that system interacts with the door and aperture mechanisms and the aircraft’s autopilot.

When that series of tests is complete, SOFIA will then make its First Light flight. This will be the flying observatory’s first official observation, and will inaugurate SOFIA’s 20-year mission to study the heavens at infrared wavelengths.

Major Science Goals

Aboard SOFIA astronomers will conduct comprehensive investigations of diverse cosmic environments, collecting data for understanding all parts of the great story of the structure and evolution of the universe. Educators, young scientists in training, and journalists will also fly on SOFIA, making it a valuable facility for public ambassador as well as a scientific training platform.

SOFIA has one huge advantage over ground-based or space telescopes — it can fly anywhere on the globe at any time to capture transient events that can be viewed only from certain locations, such as occultations of stars by planets that reveal the structure of planetary atmospheres, rings, and moons.

It will be called upon to witness out of the ordinary transient events, such as supernovae, or comets and asteroids approaching Earth.

Specifically, SOFIA will study four major astronomical areas:

1. Galaxies and the Milky Way Galactic Center
2. The Interstellar Medium of the Milky Way
3. The Formation of Stars and Planets
4. Planetary Science

Let’s take a look at each of these areas. First, Galaxies and the Milky Way Galactic Center:

SOFIA will observe faraway galaxies frozen, from our perspective, during their peak star formation period. These galaxies have red shifts between 0.3 and 1.1. Such a range provides a look back through time, from close to the present to galaxies with “starburst” peaks going back more than halfway through the history of the Universe. The observatory can detect the brightest infrared lines from these sources, with spatial resolution significantly higher than previous observatories operating at these wavelengths.

This capability will provide observations to help determine the strength and spatial extent of starbursts, addressing questions, such as whether or not these regions, where exceedingly large numbers of stars form, are confined to localized areas or are found galaxy wide. Such a survey is expected to be critical to understanding the star formation history of the Universe.

The second area of study is the Interstellar Medium of the Milky Way:

The Interstellar Medium contains an elemental record of the generations of stars that have lived and died since the galaxy’s birth. SOFIA will observe spectra of bright sources and extended regions, probing the physics and chemistry of both.

The physical processes governing how stars interact with their environments, the origin of dust, and the role of large, complex carbon molecules — notably polycyclic aromatic hydrocarbons (PAHs) — will be explored. PAH molecules are so ubiquitous that they can be used as a “dye” to trace the chemistry of prebiotic molecules within star forming regions, allowing ever deepening views into the shrouded nurseries where stellar, and eventually planetary systems, form.

SOFIA will enable a third area of study, The Formation of Stars and Planets:

A century ago no one understood why stars shine. Today, astrophysicists explain energy production in stars with great precision. Our current unknowns concern the cycles by which stars form, ignite, and replenish the clouds with gaseous remains and the heavier nuclei synthesized in their cores. Matter condenses into young stellar objects and the thick, dusty, donut shapes that obscure them. Further collapse into proto planetary disks initiates development of solar systems, as happened 5 billion years around the Sun.

Planetary Science observation capabilities are the fourth area that SOFIA will study:

Comets, near Earth asteroids, atmosphere bearing moons (such as Titan), and planets (notably Venus), betray evidence of their own origins and, by extension, that of the Solar System. Water and organic materials are clues to how solar system bodies formed, how those ingredients rained down on early Earth, and how the stage was set for the eventual appearance of life on our planet.

Science Vision and Case For SOFIA

Two documents that will be of interest to astronomers, both amateur and professional, are available as downloadable PDF files from the SOFIA website.

The first, “The Science Vision for the Stratospheric Observatory For Infrared Astronomy” is an approximately 200-page book that examines all facets of SOFIA – from the instruments to each of the four areas of scientific interest.

The second document is “The Case for SOFIA,” which is an abridged, 16-page version of the Science Vision book.

Both are available at:

Podcast recorded and produced by Martin Ratcliffe.

End of podcast:

365 Days of Astronomy
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