Optical SETI observatories in the new millennium: A review

The Optical Search for Extraterrestrial Intelligence is now 40 years old. However, it was only during the closing years of the 20(th) Century, after a 25-year hiatus, that the optical search has regained respectability in the SETI community at large. The quarter-of-a-century delay in American Optical SETI research was due to a historical accident and not for the lack of any enabling technology. This review paper describes aspects of past, present and future Optical SETI programs. Emphasis is placed on detecting fast, pulsed attention-getting laser beacon signals rather than monochromatic, continuous wave beacons. Some examples of commercial detection equipment that may be employed for either type of OSETI are given. It is expected that in time, some of the great telescopes of the world will be employed in this optical search for ETI signals. This may take the form of either dedicated observations or a type of Optical SERENDIP program, as had been done with Microwave SETI. There will also be large observatories built dedicated only to the optical search. Just as the microwave SETI@Home project has proved very popular with the public, the time has come for its optical equivalent. This paper also speculates on the eventual need to move Optical SETI observatories into space with high altitude balloons and space-based telescopes. It is expected that by the end of the first decade of the Third Millennium, the electromagnetic search for extraterrestrial intelligence on planet Earth will be dominated by SETI of the optical kind.