The world's largest telescopes for optical and near-infrared astronomy are the twin 10 m Keck telescopes on top of Mauna Kea, Hawaii.  NASA became involved in the Keck Observatory in 1990 to support its interests in detecting and studying other planetary systems.  The Toward Other Planetary Systems (TOPS) report, which formed the basis for NASA's involvement in the Keck project, advocated using the two Keck  telescopes as an interferometer to conduct these observations. The search for planetary systems is a fundamental goal of the Origins Program at NASA, which includes the Keck Interferometer and the space interferometers SIM (Space Interferometry Mission) and TPF (Terrestrial Planet Finder).  Key science programs for the Keck Interferometer directed at Origins goals include characterizing the environment around nearby stars.

On the 85-m Keck-Keck baseline, the Keck Interferometer will have a spatial resolution of 5 milliarcseconds (mas) at 2.2 microns (µm), and 24 mas at 10 µm.  The interferometer has several back-end instruments, allowing for a variety of observation types.