WISE/NEOWISE

Artist's concept of the Wide-field Infrared Survey Explorer. Image credit: NASA/JPL-Caltech

Launch Date	Dec. 14, 2009
Launch Site	Vandenberg Air Force Base, Calif. \| Launch Pad: SLC-2
Destination	Asteroids, Beyond Our Solar System
Type	Orbiter
Status	Successful - Extended Mission in Progress
Nation	United States
Alternate Names	Explorer 92, MIDEX/WISEWide-field Infrared Survey Explorer (WISE), 36119, 2009-071A

Goals

Discover and catalog everything from asteroids to the coolest and dimmest stars to the most luminous galaxies. The spacecraft was later repurposed to search for Near-Earth Objects.

Accomplishments

WISE scanned the entire celestial sky in infrared light about 1.5 times. It captured more than 2.7 million images of objects in space, ranging from faraway galaxies to asteroids and comets close to Earth. After completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold.

However, two of its four infrared cameras remained operational. These two channels were still useful for asteroid hunting, so NASA extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt. The spacecraft was then placed in hibernation in case another science opportunity arose.

Beginning in September 2013, WISE will be revived with the goal of discovering and characterizing near-Earth objects (NEOs). NASA anticipates WISE will use its 40-cm (16-inch) telescope and infrared cameras to discover about 150 previously unknown NEOs and characterize the size, albedo and thermal properties of about 2,000 others.

Key Dates

Dec. 14, 2009: Launch
Jan 2010—Feb 2011: WISE/NEOWISE Primary Mission
Sep 2013—Present: NEOWISE Reactivation

In Depth

NASA's Wide-field Infrared Survey Explorer (WISE) is a robotic Earth orbiting satellite carrying an infrared-sensitive telescope. WISE was sent to image the entire sky and provide knowledge about the solar system, the Milky Way and the Universe. Among the objects WISE studied were asteroids, the coolest and dimmest stars and the most luminous galaxies.

WISE scanned the entire celestial sky in infrared light about 1.5 times during its primary mission from January 2010 to February 2011. The spacecraft took about 7,500 images every day and captured more than 2.7 million images in multiple infrared wavelengths. WISE cataloged more than 560 million objects in space, ranging from faraway galaxies to asteroids and comets much closer to Earth.

After completing its prime science mission, the spacecraft ran out of the frozen coolant that keeps its instrumentation cold. (Since objects around room temperature emit infrared radiation, the WISE telescope and detectors were kept very cold (below -430 degrees Fahrenheit /15 Kelvins, which is only 15 degrees Centigrade above absolute zero) by a cryostat—similar to an ice chest, except it is filled with solid hydrogen instead of ice.) However, two of its four infrared cameras remained operational and were still useful for asteroid hunting. NASA then extended the NEOWISE portion of the WISE mission by four months, with the primary purpose of hunting for more asteroids and comets, and to finish one complete scan of the main asteroid belt.

NEOWISE made the most accurate survey of near-Earth objects (NEOs) to date. During 2010, NEOWISE observed about 158,000 rocky bodies out of approximately 600,000 known objects. Discoveries included 21 comets, more than 34,000 asteroids in the main belt between Mars and Jupiter, and 135 near-Earth objects. At the completion of the extended mission, the spacecraft was placed in hibernation in case another science opportunity arose.

Beginning in September 2013, NEOWISE was revived with the goal of discovering and characterizing more NEOs. NASA anticipates NEOWISE will use its 40-cm (16-inch) telescope and infrared cameras to discover about 150 previously unknown NEOs and characterize the size, albedo and thermal properties of about 2,000 others. This is a three-year extension.

Solar panels provide WISE with the electricity it needs to operate -- these solar panels always point toward the sun. WISE orbits several hundred miles above the dividing line between night and day on Earth and the telescope looks out at right angles to the sun; always pointing away from the Earth. As WISE orbits from the North Pole to the equator to the South Pole and then back up to the North Pole, the telescope sweeps out a circle in the sky.

As WISE sweeps along the circle, a small mirror scans in the opposite direction, capturing an image of the sky onto an infrared sensitive digital camera, taking a picture every 11 seconds. Each picture covers an area of the sky three times larger than the full moon. Each picture taken by WISE has one megapixel at each of four different wavelengths that range from five to 35 times longer than the longest waves the human eye can see. When active, data taken by WISE is downloaded by radio transmission four times per day to computers on the ground.