A Nasa satellite designed to uncover hidden cosmic objects is scheduled to be launched from California.
The Wide-field Infrared Survey Explorer (Wise) will blast off from Vandenberg Air Force Base on a Delta II rocket between 1409 and 1423 GMT.
It will pick up the glow of hundreds of millions of astronomical bodies.
It is expected to uncover objects that have never seen before, including some of the coolest stars and the most luminous galaxies.
It will do this by scanning the entire sky in infrared light with a sensitivity hundreds of times greater than ever before.
Viewing the sky with "infrared glasses" can lift a veil on many objects that are not visible to the naked eye.
The satellite will also have a role in planetary protection: Wise will be able to detect some of the darkest near-Earth asteroids and comets.
Wise will cast a wide net for astronomical objects of interest
This would help efforts to determine whether any of these objects could strike Earth in the near future.
Wise will join two other infrared missions in space: Nasa's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory.
This mission is different from those others in that it will survey the entire sky.
It is designed to cast a wide net to catch a variety of objects of interest, including rare oddities.