Instead of using visible light to spot incoming objects, Mainzer’s team at JPL/Caltech has leveraged a characteristic signature of NEOs—their heat. Asteroids and comets are warmed by the sun and so glow brightly at thermal wavelengths (infrared), making them easier to spot with the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope.
Phys.org
“With the NEOWISE mission we can spot objects regardless of their surface color, and use it to measure their sizes and other surface properties,” Mainzer said.