Why doesn't SETI concentrate its observations to the nearby stars and the solar systems that we are discovering?
My question or comment is that it appears to me that SETI is randomly sampling the whole sky. This will take forever. Why doesn't SETI concentrate its observations to those stars (and perhaps the solar systems we are discovering) that are nearest to us. This way, the signal would be stronger and perhaps be able to reply within a lifetime.
What you say was true in the past, but not so at present. The problem in the past was that SETI programs did not have the money to have dedicated telescopes for their work. SETI needs to detect radio signals and for this purpose needs to use radio telescopes (now, optical techniques are also being developed). As I mentioned before, until recently, SETI did not have dedicated telescopes and hence SETI programs are piggybacked onto other regular astronomical observations of radio telescopes like Arecibo. Extrasolar planets are discovered by optical telescopes and are not typical radio telescope targets.
Radio telescopes are most commonly used to look at star forming regions, supernova remnants, galaxies, etc. They look at nearby stars relatively rarely in comparison. Fortunately, radio telescopes have a rather big beam and some stars will usually be in the same field of view. However, unless a star with a recently discovered solar system fortuitously lies in the same field of view as that of an interesting radio source, or has special properties like presence of disks which can be studied in radio wavelengths, it is unlikely for them to be observed with radio telescopes. This is the reason why previous SETI researches could not concentrate on nearby stars.
However, recently, there are privately funded programs like project Phoenix that are looking at nearby stars. Project Phoenix operated in Green Bank from September 1996 through April 1998, using the telescope about 50% of the time and scrutinized the vicinities of nearby, sun-like stars. It also enabled the use of the Arecibo radio telescope for dedicated SETI research for two to three week sessions each year.
Also, currently, the Allen Telescope Array which is a dedicated SETI instrument is under the process of construction. When completed, this telescope array will be used for SETI research 24 hours a day, 7 days a week. This will permit an expansion from Project Phoenix's stellar reconnaissance of 1,000 stars to 100 thousand or even 1 million nearby stars. So, while what you say was true in the past, it is no longer true at present.
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