Almost from its beginnings in 1958, the National Aeronautics and Space Administration (NASA) set up a life-science program. Because one of the priorities of the organization is to search for life beyond Earth, NASA began designing spacecraft to unravel the mysteries of Mars. The effort to search for life on Mars culminated in the landing of two Viking spacecraft on the surface of the planet in 1976. Although the biology experiments conducted as part of these missions provided some evidence for the possibility of life, the scientific consensus was that they drew a blank. In 1996, however, the 'Mars rock' rekindled interest in life in our solar system. The discovery of an ocean on the Jovian moon Europa, of organic molecules on the Saturnian moon Titan and persuasive evidence that water once flowed on Mars suggests that the solar system is still of considerable exobiological interest. In addition, since 1995 approximately 175 planets have been found beyond our solar system. Although these discoveries are gas giants, NASA spacecraft might soon detect Earth-sized planets. The search for life in the universe continues.