Wide-Field Infrared Survey Explorer (WISE) is a satellite launched in December 2009, aimed at a 1 year mission. The aim was to image the whole sky in Infrared, aiming to observe stellar nurseries and to detect Asteroids. A reason to use infrared is that it penetrates Dust.
Differences in these, e.g., w1-w2 and w2-w3 are useful in identifying obscured Active Galactic Nuclei.
The spacecraft was put in hibernation while still operational when the intended mission was completed. It was revived for a new mission, NEOWISE (for Near Earth Object WISE), specifically to search for near-Earth objects.
Wide Field Infrared Explorer (WIRE)