The recent discoveries of other planetary systems and inconclusive evidence for ancient life on Mars have supported the long-held view that intelligent life on Earth was the result of common processes which should have occurred in many planetary systems. The most substantial controversies remaining concern the frequency with which biotas produce intelligent, technology-using species, and the lengths of time that technological civilizations produce detectable manifestations of their existence. It would appear that these two controversies can only be resolved through the detection of extraterrestrial intelligent life. In any case, the planetary and Martian discoveries encourage further searches for extraterrestrial intelligent life and have served to motivate increased contributions of resources to searches and the magnitude of the searches themselves.
Analyses of possible methods to detect extraterrestrial technology still tend to favor radio searches, and thus most current searches continue to search for radio transmissions, primarily at microwave frequencies. However, modest searches at optical and infrared wavelengths are in progress and may grow in ability in the future. It is clear that there is no logic which can conclusively identify the search method most likely to succeed, and thus all reasonable searches are worthy of support.
Progress in radio searches has been enormous over the 36 years that such searches have been carried out. The search capabilities of SETI systems have grown very nearly exponentially over that time, with a capability-doubling time of about 2/3 of a year. The search systems of today are about 100 trillion times more powerful than those of 1960. This improvement has benefited greatly by the construction of large radio telescopes. More important has been the application of modern computer technology to produce affordable multichannel radio receivers, with contemporary search systems being capable of monitoring more than 100 million channels simultaneously. Of great importance has been the development of computer hardware and software which can search for a variety of intelligent signal forms in the data produced by the multichannel system. Also of great importance has been the implementation of search systems in which two radio telescopes, widely separated, are used in approaches which allow radio frequency interference to be quickly and reliably identified. This is costly but very effective in dealing with the major impediment met in current searches, terrestrial radio interference.
A recent unfortunate development in this field has been the total withdrawal of financial support by U.S. federal agencies. This withdrawal has ignored the strong support within the scientific community for such research and appears to be driven by politics outside the scientific community. However, a positive development has been the development of massive financial support by private individuals and foundations; this support has been adequate to continue existing programs and even to improve them.
The search for manifestations of extraterrestrial technology still appears to be one of the more promising and much less costly methods to detect extraterrestrial life. If successful, it obviously will provide much more interesting data than will just the discovery that life exists on another planet.
There is still room to expand existing search systems greatly without requiring new technological developments. This can come about through the purchase of still more systems similar to those already in place. One of the most important steps which could be taken to enhance search capability would be the provision of large radio telescopes dedicated to SETI searches. These could be relatively inexpensive, since they would not need the range of capabilities normally sought in radio telescopes. Their construction would lead to faster searches, and higher quality searches, since there would be adequate opportunity to optimize all aspects of the telescope and its receiver system for SETI. It would also make searches much more cost effective by eliminating the costs involved in moving complicated search systems, and their operators, to remote sites. In the long run, a goal should be to build and operate large SETI systems on the far side of the moon, the only place in the solar system which is shielded from human radio transmissions at all times.
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Last updated Feb-10-1997
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