The WISE satellite will be an orbiting observatory that will study the sky at infrared (heat) wavelengths.
Insights to come from WISE satellite
4 Jul 2009
NASA's Wide-field Infrared Survey Explorer satellite, or WISE, has been assembled and is undergoing final preparations for a planned November 1 launch from Vandenberg Air Force Base, California.
The mission will map the entire sky at infrared wavelengths, creating a cosmic clearinghouse of hundreds of millions of objects—everything from the most luminous galaxies, to the nearest stars, to dark and potentially hazardous asteroids.
The survey will be the most detailed to date in infrared light, with a sensitivity hundreds of times better than that of its predecessor, the Infrared Astronomical Satellite.
"Most of the sky has never been imaged at these infrared wavelengths with this kind of sensitivity," said Edward Wright, the mission's principal investigator at UCLA. "We are sure to find many surprises."
< WISE will be equipped with a 40cm-wide telescope.
On May 17, the mission's science instrument was delivered to Ball Aerospace & Technologies Corp. in Boulder, Colorado, where it was attached to the spacecraft, built by Ball. The assembled unit was then blasted by sound to simulate the effects of launch. Tests for electronic "noise" in the detectors will be performed next.
The science instrument is a 40-centimetre-diameter telescope with four infrared cameras. A cryostat, or cooler, uses frozen hydrogen to chill the sensitive megapixel infrared detectors down to minus 266 degrees Celsius. The instrument was built by Space Dynamics Laboratory in Logan, Utah.
No place to hide
Among expected finds from WISE are hundreds of thousands of asteroids in our Solar System's asteroid belt, and hundreds of additional asteroids that come near Earth.
WISE is expected to find lots of asteroids. >
Many asteroids have gone undetected because they don't reflect much visible light, but their heat makes them glow in infrared light that WISE can see.
By cataloguing the objects, the mission will provide better estimates of their sizes, a critical step for assessing the risk associated with those that might impact Earth.
"We know that asteroids occasionally hit Earth, and we'd like to have a better idea of how many there are and their sizes," said Amy Mainzer of NASA's Jet Propulsion Laboratory, the mission's deputy project scientist. "Whether they are dark or shiny, they all emit infrared light. They can't hide from WISE."
The survey will also reveal the universe's most luminous galaxies seen long ago in the dusty throes of their formation, plus clouds of planet-forming dust and gas around stars, and other cosmic goodies.
Planets close to home?
The mission is also expected to find the coldest stars—dim orbs called brown dwarfs that are too small to have ignited like our sun. Brown dwarfs are littered throughout our galaxy, but because they are so cool, they are often too faint to see in visible light.
The infrared detectors on WISE will pick up the glow of roughly 1,000 brown dwarfs in our galaxy, including those coldest and closest to our Solar System. In fact, astronomers say the mission could find a brown dwarf closer to us than the nearest known star, Proxima Centauri, located approximately four light-years away.
< WISE will find brown dwarfs—dim stars—possibly with planets orbiting them.
"We've been learning that brown dwarfs may have planets, so it's possible we'll find the closest planetary systems," said Peter Eisenhardt, the mission's project scientist at JPL. "We should also find many hundreds of brown dwarfs colder than 480 degrees Celsius, a group that as of now has only nine known members."
The observations will guide other infrared telescopes to the most interesting objects for follow-up studies. For example, NASA's Spitzer Space Telescope, the Herschel observatory just launched by the European Space Agency with significant NASA participation, and NASA's upcoming James Webb Space Telescope, will direct their gaze at objects uncovered by WISE.
WISE will lift off from Vandenberg aboard a United Launch Alliance Delta II rocket. It will orbit Earth, mapping the entire sky in six months after a one-month checkout period. Its frozen hydrogen is expected to last several months longer, allowing WISE to map much of the sky a second time and see what has changed.
Adapted from information issued by NASA JPL.
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