A SEARCH FOR LIFE ON EARTH FROM THE GALILEO SPACECRAFT

In its December 1990 fly-by of Earth, the Galileo spacecraft found evi dence of abundant gaseous oxygen, a widely distributed surface pigment with a sharp absorption edge in the red part of the visible spectrum, and atmospheric methane in extreme thermodynamic disequilibrium; toge ther, these are strongly suggestive of life on Earth. Moreover, the pr esence of narrow-band, pulsed, amplitude-modulated radio transmission seems uniquely attributable to intelligence. These observations consti tute a control experiment for the search for extraterrestrial life by modern interplanetary spacecraft.