The Wide-field Infrared Survey Explorer (WISE), a NASA MIDEX mission, will survey the entire sky in four bands
from 3.3 to 23 microns with a sensitivity 1000 times greater than the IRAS survey. The WISE survey will extend the
Two Micron All Sky Survey into the thermal infrared and will provide an important catalog for the James Webb Space
Telescope. Using 10242 HgCdTe and Si:As arrays at 3.3, 4.7, 12 and 23 microns, WISE will find the most luminous
galaxies in the universe, the closest stars to the Sun, and it will detect most of the main belt asteroids larger than 3 km.
The single WISE instrument consists of a 40 cm diamond-turned aluminum afocal telescope, a two-stage solid hydrogen
cryostat, a scan mirror mechanism, and reimaging optics giving 5" resolution (full-width-half-maximum). The use of
dichroics and beamsplitters allows four color images of a 47'x47' field of view to be taken every 8.8 seconds,
synchronized with the orbital motion to provide total sky coverage with overlap between revolutions. WISE will be
placed into a Sun-synchronous polar orbit on a Delta 7320-10 launch vehicle. The WISE survey approach is simple and
efficient. The three-axis-stabilized spacecraft rotates at a constant rate while the scan mirror freezes the telescope line of
sight during each exposure. WISE has completed its mission Preliminary Design Review and its NASA Confirmation
Review, and the project is awaiting confirmation from NASA to proceed to the Critical Design phase. Much of the
payload hardware is now complete, and assembly of the payload will occur over the next year. WISE is scheduled to
launch in late 2009; the project web site can be found at www.wise.ssl.berkeley.edu.