The two years previous to 1997 have produced some of the most exciting results in the history of astronomy: the indirect detection of planets beyond our solar system. The study of the characteristics and physical nature of exo-planets requires an infrared interferometer in space. Such observatory would directly detect the thermal emission from exo-planets and would allow us to see signatures of molecules, such as water, ozone and carbon dioxide, in their atmospheres. The presence of such molecules would be strong evidence for exo-life. In addition, this kind of instrument would help to clarify important questions concerning the birth and death of stars and extragalactic astronomy. In Toledo, scientists and engineers from both sides of the Atlantic met to discuss the technological challenges of an infrared space interferometer and its scientific capabilities, particularly those related to exo-planetary systems and Earth-like planets.

The past year has produced some of the most exciting results in the history of astronomy, particularly in the area of planets outside our solar system. Only a half-year before our meeting in Toledo, Spain, the first unambiguous detection of planet-sized masses orbiting main sequence stars were reported. Since that time, evidence for a new exo planet has been reported almost at the rate of about once per month. Some of these objects are likely to turn out to be very low-mass stars, but something like half show characteristics - Jupiter-like mass and near-zero orbital eccentricity - which appear to be unique to planets. Almost at the same time that giant planets were being discovered regularly, the two major space agencies, ESA and NASA, have iden tified searches for and detailed study of Earth-like planets as a major priority for the future. In ESA's "Horizon 2000 Plus" programme, an infrared interferometer has been proposed as a possible future Cor nerstone mission. Similarly, scientists in the US produced the "Road Map for the Exploration of Neighboring Planetary Systems (ExNPS)", which provided NASA with a long-term plan which leads also to an infrared interferometer in space to study hypothetical Earth-like worlds beyond our Solar System. Such an observatory is designed to search for the thermal emission from a family of planets, using interferometric nulling to remove the contaminating light from the central star.