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Science of the SOFIA
milky way galaxyImage above: This Spitzer Space Telescope infrared image of the Milky Way galaxy represents the type of astronomical objects that will be of interest to investigators when the SOFIA is fully operational.

The only thing more impressive than an airborne observatory that carries a 17-metric-ton telescope is the potential for equally weighty new breakthroughs in astronomy.

The vast array of science driving work with the Stratospheric Observatory for Infrared Astronomy, or SOFIA, boils down to this: "The most exciting science is really trying to understand the chemistry and, potentially, the biology that's going on in space, and really getting to the heart of the question of, did life form here on Earth, or did it form out in space?" said Eric Becklin, SOFIA chief scientist and a pioneer in the field of infrared astronomy.

The SOFIA alone won't be able to answer the questions of where life began - about 15 scientists will be directly working on the SOFIA science mission - but the airborne observatory will undoubtedly contribute to revolutionary new ways of looking at the universe.

To those ends, as many as another two or three dozen scientists around the world - including about 10 from Germany, a key SOFIA partner - are continuing to push the state of the art in research instrumentation, said Becklin, a 42-year veteran of infrared science. Science data gathered from the SOFIA also will be analyzed by hundreds of additional scientists.

NASA's Kuiper Airborne Observatory, which was based at Ames Research Center at Moffett Field, Calif., for 21 years, was the first of its kind. The SOFIA program is expected to pick up where the Kuiper's work ended in 1995 when that aircraft was retired.

"One of the things that SOFIA can do that Kuiper couldn't do is - because of (the SOFIA telescope's) large 2.7-meter (over eight-foot) aperture, it actually has a clearer view of the universe. We'll have a sharper view. In fact, it will be the sharpest view we'll have at some of the wavelengths we're looking at," said Becklin, who also was a principal investigator aboard the Kuiper.

Wavelengths are the sections of the electromagnetic spectrum under which astronomical phenomena can be seen.

The SOFIA will have other advantages compared with those of its predecessor, and will offer capabilities that complement the work of other observatories currently in use.

Image above: The Spitzer Space Telescope captured this infrared image of the Helix nebula.

"Relative to the Kuiper, we'll definitely see deeper into space. Relative to space observatories like Spitzer or ISO we won't necessarily go deeper," he said, referring to NASA's space-based infrared Spitzer Space Telescope and the European Space Agency's Infrared Space Observatory satellite.

"In terms of sensitivity - we'll be more sensitive than the Kuiper, we're about the same as the European space observatory and we won't be as sensitive throughout the infrared as Spitzer, which is flying presently, but our images will be sharper," he added. "We will also make measurements at wavelengths that are not covered by ISO or Spitzer."

In addition, the SOFIA will offer advantages over ground-based assets by "observing" above the water vapor that obscures celestial subjects when they're viewed from Earth. "(Use of the SOFIA) opens up a whole new range of observations in the electromagnetic spectrum that can be observed - that you just can't do from the ground -- and that's especially true of infrared," Becklin said.

Observations made in the infrared spectrum offer many advantages over those made through other wavelengths.

"An advantage of infrared is that it 'peers' through the dust that's out in space. There's a lot of dust in space; it's between stars. The view that we get of the universe in the optical or ultraviolet (wavelength) is biased by dust. SOFIA will probe right through that dust," he said.

"In the visible and ultraviolet, you're mainly looking at stars. When you look in infrared you see stars, but also see (more clearly) the dust and the gas that those stars formed from or are throwing off as they die. You really get a different view of the universe when you look in the infrared," added Becklin, who in 1968 completed his doctoral thesis on the exact center of the Milky Way galaxy.

Image above: SOFIA chief scientist Eric Becklin is a pioneer in the field of infrared astronomy. He's ready to continue his work when the flying observatory is ramped up for science missions during the next two years. While the Kuiper Airborne Observatory revolutionized the field of infrared astronomy, the SOFIA's larger telescope and latest instrument upgrades will help scientists delve deeper into mysteries of the universe such as star birth and death. (NASA Photo by Tony Landis)

Another of Becklin's achievements includes discovery of the first known protostar (a forming star) in the heart of the Orion nebula, which, along with partner astronomer Gerry Neugenbauer, he discovered in 1966. Their discovery is known as the Becklin- Neugenbauer Object. Becklin also served as the first director of the NASA Infrared Telescope Facility at Mauna Kea, Hawaii. Becklin's experiences make him a good fit for the job of SOFIA chief scientist. In his newest role he said he looks forward to using the SOFIA's new and seasoned instruments, which will make it much easier to detect differences along the electromagnetic spectrum.

"We can split up the light with a spectrometer that ... allows you to look in detail at what's in the spectrum. Then you start seeing lines due to the atoms and molecules that are out in space. We can study in much greater detail the chemistry out in space and even the biology. Potentially, we have the ability to see some organic signatures that would indicate if life is forming out there," he said.

A spectrometer is an instrument incorporated into the SOFIA telescope system to detect and divide heat radiation from space. Spectrometers were a hallmark of the Kuiper Airborne Observatory science and will be important on the SOFIA - five of nine instruments intended for use on early missions are spectrometers. It's a tool with which Becklin is well acquainted and one he continues to use to study space molecules and failed stars like brown dwarfs. "Science is the progress of always doing things better by looking fainter, or deeper into the universe, with greater clarity, or with greater spectral resolution that allows you to separate more molecules and atoms," he said. The SOFIA's mobility also gives it some big advantages over space-based telescopes.

"There are certain astronomical observations and events that happen in only certain places on the Earth," he said. "An example of that is an eclipse of the sun. You can study eclipses, and there are similar events called planetary occultations [through which] you can study planets. So you can study the sun or moon in a solar eclipse and you can study the planets in a planetary occultation. They happen in only certain spots on the Earth." The SOFIA's mobility, he said, will allow astronomers to dispatch it to strategic locations for observing such events.

The capability of returning to a home base is another plus, because it allows researchers to take risks that would be cost-prohibitive with technology on a space-based telescope.

"We come home every night and we can put on the latest and greatest instrumentation," he noted.

"Because we're on an airplane platform, we can fly big instruments and quite complicated instruments that you really wouldn't want to put into space. We also have the potential to fix problems. In the space program, some problems put you down completely. We will always be continually improving, modifying and fixing any problems we have with the aircraft, telescope and instrumentation." Becklin said SOFIA science will also be able to shed light on key questions about formation of the universe and hydrogen atoms.

"There are some phenomena that we'll see for the first time because of the great resolution. One of those molecules that we'll see in greater detail than anyone has before is the deuderated molecular hydrogen," which is made up of one normal hydrogen atom and one deuterated hydrogen atom. A hydrogen atom, he explained, has one proton in its nucleus. Deuterium has a proton and a neutron in its nucleus and is called heavy hydrogen. "Now we have heavy molecular hydrogen, a deuterium atom and a hydrogen atom together. With our spectrometers, we can do the best studies that have been done so far on deuderated molecular hydrogen."

It is this hydrogen investigation that could potentially lead to answers about the universe's origins, he said.

"That deuterium we'll be studying will have formed in the Big Bang, and understanding how much [of it] is out there and how it's been destroyed are key questions to trying to understand how the universe began." A discovery's implications might not be understood until later, such as was true of another of Becklin's observations that currently are a hot topic in astronomy - "buckyballs."

Buckyballs - dubbed C60 after their makeup was identified as 60 carbon atoms arrayed in a spherical shape - were discovered by British astrophysicist Harold Kroto, who in the 1980s was at work analyzing radio patterns of carbon in space dust. Their moniker acknowledges 20th century innovator R. Buckminster "Bucky" Fuller, designer of the geodesic dome, the shape of which buckyballs resemble.

Kroto was observing an object in the sky, IRC+10216, of which Becklin had made the first measurements as a graduate student. For lab studies identifying C60 and carbon, made to support their astronomical observation, Kroto and a team of researchers received the 1996 Nobel Prize in chemistry.

Buckyballs hold promise because of their superconductivity and for the potential they hold for researchers using them as building blocks for nanotechnology. The carbon balls already have been used for constructing nano tubes that could benefit the medical field. Buckyballs have not yet been identified in space; however, it should be possible to locate them near carbon stars that give off exhaust in much the same way cars on Earth do. Becklin hypothesizes that buckyballs exist in space and will be discovered by the SOFIA when it becomes operational.

"We believe they're probably out there, and we're hoping to see them," he said.

SOFIA mission content will be based on the number of hours available for research and on proposals submitted. Researchers will present their case for use of the SOFIA and peer reviews will determine which proposals are accepted. What is clear is that the SOFIA is certain to observe a wide variety of astronomical phenomena.

Becklin hypothesized that the SOFIA will be engaged in investigations of planets in this solar system and of new planets discovered in other solar systems, in collections of stars, the black hole at the center and edge of the Milky Way and material surrounding it.

"It's hard to predict what will be seen, because discoveries are almost always a surprise," he said.

As a key component of NASA's astrophysics program aimed at exploring fundamental questions about the universe, the flying observatory will add to astronomers' understanding of star birth, formation of the solar system, the nature and evolution of comets, the origins of complex molecules in space, how galaxies form and change and the mysterious black holes in the center of galaxies.

Becklin and his colleagues have their work cut out for them. And they can't wait to get started.

Jay Levine
X-Press Editor