Utah photographic telescope recording stellar images of space
An orbit-based, Utah-built telescope and camera has scientists cheering after it returned crisp test images of the starry sky last month.
NASA's Wide-field Infrared Survey Explorer, or WISE, will begin surveying the sky Thursday for millions of hidden objects, such as asteroids, comets, "failed" stars and forming galaxies. Scientists expect WISE will unleash a "firehouse" of astronomical data that will rewrite our understanding of the universe.
"So far WISE is living up to expectations," said John Elwell, a project leader with the Space Dynamics Laboratory (SDL) in Logan. "The instrumentation has been working almost flawlessly. Image quality is meeting requirements on all four colors."
The goal of WISE is creating a high-resolution map of the sky by systematically taking millions of photographs as it orbits. Scientists predict WISE will locate thousands of objects that were previously unknown because they do not emit the kind of light that can be seen by the human eye.
These objects, like brown dwarf stars, do not emit much light, but they do emit heat whose long wavelengths can be detected in the infrared spectrum. WISE's four-color camera will record wavelengths five to 30 times longer, or redder, than visible light, bringing into view thousands of new objects.
WISE will shoot an image every 11 seconds as it orbits Earth during the next six months.
Considering the camera is mounted on a satellite traveling 17,000 mph, the 11-second exposures posed a technological hurdle as far as achieving crisp images. To solve it, SDL built a mirror that moves in tandem with the satellite's movement, Elwell said. The mirror holds the images still during the exposure, then snaps to the next starting point for the next exposure.
"You could get streaky, blurry images if the motions aren't matched up," said chief project scientist Peter Eisenhardt, of NASA's Jet Propulsion Laboratory. "SDL did a great job. Everyone breathed a sigh of relief when those images came back in focus."
SDL, a part of the Utah State University Research Foundation, engineered the WISE instruments under a $76 million contract with NASA. Engineers wrapped the telescope in a Thermos-like lining of solid hydrogen to keep it chilled to minus 445 Fahrenheit so the camera would not be blinded by the equipment's own warmth. Scientists have just 10 months before the hydrogen vaporizes, so any delays will undermine WISE's chances of success.
The WISE satellite launched Dec. 14 and two weeks later JPL officials ejected its cover. Shortly before midnight on New Year's Eve, WISE began transmitting calibration images that will be used to fine-tune the instruments.
The "prettiest" of about a dozen images that JPL has analyzed shows 3,000 stars in the Carina constellation, covering an area about as big as three moons.
"It proves our new telescope is going to work," Eisenhardt said. "It's not anything special, but it's like the first picture of a new baby, so it's special to me."
Plainly visible in the center right part of the photo is a "red giant" star, about 1,000 light years from Earth. Eisenhardt expects WISE will detect many more red giants and other failed stars, such as brown dwarves.
These diminutive stars lack the mass to sustain fusion, the nuclear reaction that illuminates the sun, so they drop out of sight but remain warm.
"We know there are as many failed stars as normal stars. If we go 100 light years from our sun there are 100 star systems, but we know of only five failed stars," Eisenhardt said. "We will find 100 new neighbors and even odds that one will be closer than our closest known neighbor. There are also good odds these nearby stars will have planets around them."
NASA will begin to release survey photos early next month.