During the December 1992 flyby of Earth, Galileo conducted another experiment to see if visible-light lasers could be used to communicate with spacecraft. The Galileo Optical Experiment (GOPEX) was successful; scientists on Earth fired a series of bright laser pulses from ground stations in California and New Mexico, and Galileo took digital pictures of the pulses, successfully detecting about one-third of them up to a distance of nearly four million miles.