The U.S. space agency NASA is about to launch another space telescope that it says will open a new window to the universe. Unlike the observatories currently in orbit, this one will scour the heavens for infrared radiation to examine parts of the cosmos previously out of view.
NASA says its Space Infrared Telescope Facility promises to open our eyes to celestial objects too far away, too cold or too dust-covered to be seen in any other way.
The chief of the program, Lia La Pianasays she has high hopes for the new observatory, known by its acronym, SIRTF. "I believe SIRTF will significantly increase our understanding of the universe and will probably rewrite the astronomy textbooks," she said, "just like the Hubble Space Telescope did."
SIRTF will look at the universe in a way Hubble and another orbiting telescope, the Chandra Observatory, cannot. It has the world's most powerful infrared cameras, allowing it to detect the long wavelengths of light below the visible light spectrum from distances the others cannot.
In contrast, Chandra captures short wavelength x-rays above the spectrum, radiation emitted by the hottest heavenly objects roiling at millions of degrees. The chief mission of the Hubble telescope is to detect the medium length, visible light from bodies at temperatures of thousands of degrees. It, too, has an infrared camera, but it is far less powerful than those on SIRTF.
As a result, NASA scientist Michael Werner says the new observatory will have a superior ability to gaze at the coldest objects in the heavens, which give off little detectable radiation except infrared.
"We can look at cold things with SIRTF, regions between the stars where new stars are forming, dust around stars that may be giving birth to planetary systems, [and] cold things at the outer fringes of our solar system," he said.
SIRTF will also have the advantage over Hubble and Chandra when observing the oldest, most distant galaxies, since most of their light is infrared. University of California astronomer Garth Illingworth says this is because light from bodies receding from us in the expanding universe shifts downward into these lower frequencies, just as the sound of a horn from a passing car drops in pitch.
"This is going to be a wonderful resource for looking at objects in the early universe," said Mr. Illingworth. "SIRTF will unveil galaxies that are hidden from us in the optical images that we're seeing to date or even in the infrared images that have been taken to date because it's just so much more powerful."
The dust that enshrouds our universe will not deter SIRTF because infrared light passes through it.
To work best, the telescope must orbit above Earth's obscuring atmosphere. It must also be far away from Earth's own infrared radiation, which could interfere with infrared signals from elsewhere.
To minimize the observatory's infrared heat, liquid helium will cool it in orbit to nearly absolute zero, -273ş Celsius, the temperature at which all atomic motion stops. Furthermore, NASA's Michael Werner says SIRTF will always be shaded by its solar panels.
"SIRTF is a cold telescope in space," Mr. Werner explained. "SIRTF will be 100 to one million times more capable than any previous facility for infrared astronomy. SIRTF does not just meet our requirements. It exceeds our requirements."
The new telescope is the fourth of NASA's great observatories following Hubble, Chandra, and the now-defunct Compton observatory, which saw the universe in ultra-high frequency gamma rays during the 1990s.
Garth Illingworth says the three remaining telescopes will complement each other, often giving different views of the same celestial object to provide astronomers a broader understanding of it. "As we learn something on one telescope, we can follow it up with another of the great observatories to put more of the jigsaw puzzle into place, because learning about how galaxies formed, when they formed, how they come together and assemble and grow with time is really and truly one of the great quests for the next decade," said Mr. Illingworth.
Launch of SIRTF is currently set for Monday, August 25, and the telescope should begin returning data about two months after that, after ground controllers have tested its instruments.
