ITHACA, N.Y. -- This summer, NASA will sponsor four young scientists who will work on analyzing data from the largest infrared telescope to be sent into space. The telescope, called SIRTF, for Space Infrared Telescope Facility, is scheduled for launch on April 15 and will circle the sun in an orbit that trails just behind the Earth's.

One of the SIRTF fellows, Henrik Spoon, an astrophysicist at the University of Groningen in the Netherlands, will work at Cornell University as a postdoctoral researcher with James Houck, the K.A. Wallace Professor of Astronomy.

Houck is the principal investigator on the infrared spectrograph, one of three instruments to be carried aboard the orbiting observatory. With data from SIRTF, Spoon will study the nature of heavily obscured power sources in ultraluminous infrared galaxies (ULIGs), which are many times brighter that most known galaxies at infrared wavelengths.

Spoon's fellowship comes with a precious commodity: 10 hours on the new telescope dedicated solely to his research. He is excited, he says, "to be part of the team of dedicated astronomers and engineers pushing the limits of infrared astronomy, to chart the unknown infrared universe beyond what previous infrared satellites could see."

The three other researchers to receive SIRTF fellowships are Michael Cushing of the University of Hawaii, who will work at NASA-Ames Research Center on the chemistry of low-mass stars and brown dwarfs; Sarah Gallagher of Pennsylvania State University, who will work at the University of California-Los Angeles on broad absorption line quasars; and Jacqueline Kessler of the California Institute of Technology (Caltech), who will do research at the University of Texas on the evolution of grains and ices in low-mass stars. The fellowships were awarded by the SIRTF Science Center at Caltech.

The ULIGs that Spoon will study were discovered in the early 1980s with NASA's first infrared telescope, the Infrared Astronomical Satellite (a mission in which Cornell astronomers played a key role). Later, the European Space Agency's Infrared Space Observatory (ISO) yielded a more detailed map of about a dozen of the galaxies, which were found to be colliding galaxies. The source of their enormous luminosity could be due to star formation or to the accretion of gas onto a massive central black hole, hidden behind the thick layers of enshrouding gas.

"There are a couple of ways that these things can produce their energy, and hence their luminosity," says Houck. "One of them is to form stars very rapidly -- maybe 1,000 times faster than our galaxy. Another is to harbor a large black hole in the center of the galaxy that shreds stars as it swallows them. The gravitational energy that these shredded stars release is converted into infrared light, and that makes them luminous."

Still other ULIGs, says Houck, might be hybrids, fueled by a combination of both black holes and superintense star formation. And, since only a handful of the galaxies have been observed in detail, there could be unknown processes driving still more types of bright galaxies.

SIRTF's infrared detectors are 100 times more sensitive than those of its predecessor, ISO. Spoon observes that until the 1950s astronomers were able to observe the universe only in visible light. Now they can conduct their surveys in "invisible colors" as well, including the infrared and ultraviolet. But in order to study the universe in most infrared colors, a telescope needs to be taken above the atmosphere. "The SIRTF satellite will allow me to study the ULIGs in a very broad range of infrared colors, without any missing color in between," says Spoon. These colors could turn out to be critically important to understanding the true nature of the ULIGs, he notes.

Houck says that trying to observe objects in deep space in the infrared from a telescope on Earth is akin to "trying to look at a distant mountain with a pair of binoculars that are on fire. That's very close to what the situation is -- there's so much light from the flaming binoculars, you can't see the mountain. The other problem is that the Earth's atmosphere is opaque to almost all wavelengths of infrared light."

SIRTF will be the fourth and last in NASA's Great Observatories Program, joining the Hubble Space Telescope, the Compton Gamma Ray Observatory and the Chandra X-Ray Observatory. The mission is managed by NASA's Jet Propulsion Laboratory, and other participating institutions include Caltech, the Smithsonian Astrophysical Observatory and the University of Arizona.

This release was prepared by Lissa Harris, a Cornell graduate student and Cornell News Service science-writing intern.

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o SIRTF: http://sirtf.caltech.edu