After 13 years of planning and building, NASA's latest high-flying telescope—seen above during an April test flight—opened its infrared eye for the first time last week from aboard a modified Boeing 747 jumbo jetliner.
SOFIA fills an important niche in modern astronomy, according to mission managers. The unusual observatory is expected to be able to see 80 percent of the infrared light visible to space-based infrared telescopes, but at a fraction of the cost to launch and maintain. (Explore a telescope time line.)
"This allows us to observe targets in the night sky that are simply out of reach of ground-based telescopes."
Photograph courtesy Jim Ross, NASA
SOFIA Spies Jupiter
During its first scientific mission, SOFIA flew to an altitude of 35,000 feet (10,700 meters) and spent eight hours observing on May 26.
One of the observatory's very first infrared pictures was a unique, multicolored view of Jupiter (above right), which showed the planet's heat in unprecedented detail. A recent visible-light picture of Jupiter (above left) taken from the ground shows the planet's familiar bands of clouds.
"The crowning accomplishment of the night came when scientists on board SOFIA recorded images of Jupiter," said SOFIA senior science advisor Eric Becklin. "The composite image from SOFIA shows heat—trapped since the formation of the planet—pouring out of Jupiter's interior through holes in its clouds."
Photograph courtesy Anthony Wesley (left); image courtesy NASA
SOFIA's Eye Opened
With the plane's rear door opened, the 8.2-foot (2.5-meter) primary mirror of SOFIA's telescope catches the light during ground testing in May at NASA's Dryden Aircraft Operations Facility in Palmdale, California.
The telescope is securely mounted into the jet plane on a spherical bearing. The base allows the instrument to be "held about as stable as a mountaintop telescope sitting on a 10-meter [33-foot] cement foundation" while the plane is in motion, according to the SOFIA team.
A custom deflector on the edge of the door helps keep strong winds from directly hitting the telescope.
From its unique aerial platform, SOFIA's infrared vision should be able to penetrate interstellar gas and dust to study how stars and planets form, to see how organic materials necessary for life may evolve, and even to watch the inner workings of black holes at the centers of distant galaxies. (Related: "'Comets' Found Orbiting Monster Black Hole.")
Photograph courtesy Tom Tschida, NASA
The infrared telescope isn't the only piece of hardware hitching a ride inside SOFIA's revamped cabin. Above, scientists and engineers test the star-trackers and other equipment used to control the telescope and process data in September 2009.
Celestial objects seem to move in arcs across the sky due to Earth's rotation, so a telescope—on land or in the air—can observe a target only so long before it sets below the horizon. The motion of the airplane plus the ability to remotely aim the telescope help SOFIA's scientists track their targets for hours at a stretch.
During the first observing mission, an international team of ten scientists and engineers spent nearly eight hours gathering data on a handful of celestial targets. Starting in 2010, NASA hopes SOFIA will rack up at least a thousand hours of in-flight science observations a year.
Photograph courtesy Tom Tschida, NASA
Engineers carefully pour liquid helium, a coolant, into the casing around the Faint Object infraRed CAmera for the Sofia Telescope, or FORCAST, in May. FORCAST, designed and built by a Cornell University team, is the first instrument to receive infrared light from the telescope's mirrors.
To see in infrared, which is essentially heat, the camera needs to operate at extremely cold temperatures—only a few degrees above absolute zero (−459.67°F or −273.15°C). Even in the cold environment of space, NASA's Spitzer Space Telescope needed liquid helium to operate most of its infrared cameras. Spitzer's coolant ran out in May 2009 after more than five years of operations, but two of its detectors are still able to work "warm."
Photograph courtesy Tony Landis, NASA
Drawing a Blank
A technician measures the 9.8-foot-wide (3-meter-wide), 8,377-pound (3,800-kilogram) "blank" for SOFIA's primary mirror in an undated picture. Made of a glass-ceramic composite that doesn't expand when it's warmed, the blank was ground down as part of the mirror-production process, which took place in Germany.
Awaiting its final reflective metal coating in October 2004, SOFIA's primary mirror is backlighted to reveal the honeycomb pattern of its internal structure. The glass-ceramic mirror was cut like this to be light enough to fly aboard a modified Boeing 747 jetliner.
After cutting and polishing, the 8.2-foot (2.5-meter) mirror weighed in at a mere 1,900 pounds (862 kilograms). (See more telescope pictures.)
Photograph courtesy Ron Strong, NASA
Lying on the floor of the mirror-coating chamber at the NASA Ames Research Center in California, two technicians in clean-room suits take a self-portrait: a picture of their reflections in SOFIA's newly coated main mirror.
The glass-ceramic mirror was coated with highly reflective aluminum to best bounce light from distant objects onto a smaller, secondary mirror suspended above, which in turn bounces the light onto a third mirror, mounted at the center of the main mirror. This third mirror is angled to send the light down a long tube to the telescope's focal point. (See an animation of SOFIA's optical system.)
Like the telescope's mirrors, its mounting (not pictured)—or mirror cell—had to be made especially lightweight to fly aboard the 747. Unique among astronomical telescopes, SOFIA's mirror cell is composed of a carbon fiber-reinforced plastic, more commonly used in tennis rackets and sailboat hulls.
Photograph courtesy NASA
SOFIA Heads Home
SOFIA banks over the Dryden Aircraft Operations Facility in Palmdale, California, on January 15, 2008. Just a few months prior, NASA had selected Dryden as SOFIA's permanent base of operations.
With its first scientific flight completed in May 26, 2010, SOFIA has a long waiting list of researchers wanting to take to the skies aboard the infrared observatory. Astronomers hope to have dozens of routine observing runs on the docket by 2011, ramping up to as many as 150 flights a year by 2014.
If all goes as planned, SOFIA should have its flying eye on the cosmos working for the next 20 years.