The WISE space telescope has cast aside its lens cap and is taking infrared images of distant stars. NASA releases the very first image.
Editors' note: This slideshow was initially published December 30, 2009. It was updated January 7, 2010, with the first image from WISE, of the constellation Carina.
NASA on Wednesday released the very first image taken by its Wide-Field Infrared Survey Explorer (WISE) space telescope, an infrared "snapshot" of the constellation Carina, located near the Milky Way. The "first light" image, seen here, shows roughly 3,000 stars; it was captured shortly after the telescope's protective cover was removed last week, according to NASA.
A little over a week earlier, on December 30, NASA engineers aiming for new images of the stars did what every photographer needs to remember to do before taking snapshots--they removed the lens cap. In this case, they sent signals to the WISE spacecraft to jettison a cover that protected the optical gear during launch and helped to keep it chilled.
A Delta II rocket carrying the telescope into Earth's orbit lifted off from Vandenberg Air Force Base in California on December 14. (The image here shows the WISE logo emblazoned on the payload fairing near the top of the Delta II rocket at Vandenberg AFB's Space Launch Complex 2.)
This infrared view of the Milky Way galaxy was taken in the late 1990s by the Midcourse Space Experiment (MSX), a project of the Ballistic Missile Defense Organization that covered only a portion of the nearby heavens. Images from the WISE telescope will have a similar resolution and sensitivity but will cover a much wider expanse, performing the most detailed infrared survey of the entire sky to date, NASA said.
At the far end of the telescope tube is the primary mirror. After this picture was taken in October, the optical system was disassembled for painting, at which time the mirrors were to get a thin coating of gold, which NASA says is a good reflector of infrared light.
The back end of the optical system (domed top, flat bottom) holds the imager optics, which will reformat star images from the telescope's scan mirror so that the images fit correctly onto WISE's detectors. In front here is the scan mirror, a mechanical system (looking remarkably like the inside of a door lock assembly) that secures a star image for the appropriate exposure time.
"To take still images on the sky as it orbits around Earth," NASA says, "WISE will use a scan mirror to counteract its motion. Light from the moving telescope's primary mirror will be focused onto the scan mirror, which will move in the opposite direction at the same rate. This allows the mission to take 'freeze-frame' snapshots of the sky every 11 seconds. That's about 7,500 images a day."
WISE has an image resolution of 4 million pixels, achieved through the use of four detectors (with about 1 million pixels each). This particular detector is a Cadmium Telluride Focal Plane Mount Assembly (HgCdTe FPMA); the green area is sensitive.
When the last infrared survey took place, in 1983, that era's Infrared Astronomical Satellite (IRAS) had at its disposal a total of only 62 pixels.
For WISE to function properly, the science instrument needs to avoid having the spacecraft's own heat interfere with the infrared glow given off by the space objects that it's viewing. That chill--as low as 8 Kelvin, or minus 447 degrees Fahrenheit--is achieved through this vacuum-sealed device, the cryostat (which is filled with frozen hydrogen), and now also through the vacuum of space. The coolant is expected to last about nine months before evaporating, NASA says, during which time WISE will have surveyed the sky one-and-a-half times.
Like many other spacecraft, WISE gets its power in orbit via solar panels, seen here as it gets a weigh-in at Vandenberg AFB in September. The spacecraft tips the scales at a little more than 1,400 pounds. It stands just over 9 feet high and around 6 feet across.