The radio SETI experiment as we know it today emerged because the technology, engineering expertise, and scientific tools became available to carry out the search. In the emerging variety of possible search strategies for ETI it makes sense to survey the scientific instruments at hand and determine how we can apply them. Optical SETI (OSETI) is an example of a strategy that has taken advantage of emergent technologies, (e.g. CCD detectors, DSP chips, optical analysis software, etc.) and devised a practical means of applying them in its search for optical transmissions from ETI. Because of its insistence on following scientific methods and adherence to acceptable engineering practices, OSETI has become a scientifically permissible, and welcome new strategy; the debate about its value is settled.
Debate continues within the SETI community about the merit of searching for extraterrestrial interstellar probes. The value of the search has been downplayed primarily because of arguments surrounding the cost and speed of interstellar travel, the economy of sending photons over baryons and to a lesser degree the Fermi paradox, which enjoys popularity as long as you don't broaden your search horizon. Since we don't know the limits of technology within the universe it is presumptive to believe that in all cases photons are preferred over baryons. We are too young to know which is really better! As our technology matures maybe we'll find out in the next century or so. Logically, a civilization just 2,000 years or more technologically experienced than us has determined which is better and is using the preferable technology in their exploration of the cosmos. It is very likely that autonomous intelligent probes are the tool of choice in interstellar exploration and contact.
We cannot deny that Earth is a fascinating and lively place, and if we have found it worthy of direct study, so would advanced ETI if they had the means. The arguments in favor of interstellar exploratory probes are not new, but are worthy of reconsideration based upon our own rapidly expanding exploration of the solar system using robotic spacecraft. Robert Freitas elaborates the probabilities of interstellar exploration by advanced civilizations quite convincingly in his writings, as do other respected researchers like Ronald Bracewell, Allen Tough, Bruce Cornet, and the late Chris Boyce.
If the arguments favoring a search for visiting interstellar probes are sensible, is there any overpowering reason why we should not be searching for them now? Is it too expensive? Are there no proper scientific instruments to search with? Is the scientific community staunchly opposed? Will governmental/political elite's interfere? Is the public not interested? Actually, the answers to these questions is no; there is nothing really significant standing in the way of carrying out a first-rate scientific search for ETI probes. Affordable instrument technologies and expertise exist enabling the organization of a professionally staffed research project with the goal of determining if there are ETI probes surveying our solar system or planet. Indeed, it will take time and effort to build testable hypotheses, to write post-detection protocols, to justify where to methodically look, and the design, engineering, construction and deployment of autonomous computer-controlled observational platforms to detect and collect a wide range of data. It will also take time to statistically analyze the data collected to determine if ETI has been detected.
A strategy to search for ET visitation (SETV) by robotic probes serves to compliment the existing SETI efforts. Radio SETI is but one valued tool in the search for ETI and a strategy like SETV does not reject or invalidate radio SETI. It adds bandwidth by focusing on near-Earth or solar system targets rather than on distant stars. Adding new types of instruments and methods to the search will not make the traditional method of radio SETI obsolete. If those in SETI are truly interested in detecting ETI should it matter by what scientific method? No! In fact, OSETI and SETV efforts better the odds of SETI being successful. Adding new strategies to the SETI observational experiment is analogous to becoming multilingual and international rather than monolingual and provincial.
The SETI community must grant its support to serious efforts to search for ETI probes, like SETV, and not only because the observational tools and talent exist to carry out an effective search. If probes are the exploratory device of choice among advanced extraterrestrial civilizations, then proving the existence of just one would at least answer the question "Are we Alone?"
Author's Note: The opinions expressed in this editorial are personal and in no way represent officially sanctioned attitudes, beliefs, interests or policy of NASA, JPL or Caltech.
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this page last updated 4 January 2003
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