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Active Assessment of Active SETI
by H. Paul Shuch, Ph.D.

Almost since its inception nearly half a century ago, SETI science has seen its supporters wage a running battle over the question of transmissions from Earth. Deliberate transmission of signals into space, sometimes called Active SETI, is justified by its proponents on the grounds of reciprocity. That is, some argue, we cannot in good conscience search for signals which we would hope other civilizations might choose to beam our way, if we ourselves are not willing to transmit such signals from Earth. The counter-argument involves the safety, and some would say the very survival, of our planet. Critics to Active SETI point out the dangers of shouting in the jungle. Radio amateurs in support of Active SETI counter that (1) the cat is already out of the bag, as we have been inadvertently transmitting to the stars for a century or so, and (2) if everybody's listening and nobody calls CQ, the bands will appear dead to all concerned.

Eloquent arguments on both sides of the issue have appeared in the pages of SearchLites, and on The SETI League's website, since our organization was founded more than a decade ago. They reflect a very real concern on the part of parties subscribing to two diverging philosophies, but I find it interesting that the argument itself evidences a significant agreement: all seem to accept as a given the existence of technological civilizations beyond Earth. The existence of ETI would appear no longer open to question; only its intensions are a subject of debate.

Recently, the arguments about the advisability of transmitting from Earth have led to renewed efforts to establish international transmission protocols. Predictably, there are those who would urge no policy restrictions against free flow of information to the stars, and others who would restrict transmission from Earth, or at least subject it to political scrutiny prior to deeming it acceptable. The problem with such discussions is that, regardless of the side of the issue a given person takes, the parties seem to desire a blanket and inflexible policy, one that fails to consider the merits and risks of transmissions on an individual basis.

But, despite the language of any constitution, not all transmissions are created equal! The benefits and risk of a given interstellar transmission are related to its power relative to the electromagnetic background, to its duration, its directionality, its bandwidth, and its information content. Even the most cautious critic of Active SETI will recognize that some transmissions are so unlikely ever to be detected that their potential impact (be it for good or for ill) is negligible. Other transmission scenarios can be envisioned which would so mark Earth as an aggressive and inconsiderate planet as to alarm even the staunchest proponent of Active SETI. So, any blanket policy (either for or against transmission) which fails to distinguish between signals is missing an important point.

Is it not possible to evaluate individual Active SETI proposals in terms of their potential impact, perhaps quantifying each on some sort of objective scale? Our Hungarian friend and colleague Ivan Almar thinks so, and last Spring he proposed, at a SETI conference in San Marino, a new analytical tool to do just that. Now called the San Marino Scale, Dr. Almar's proposal has been discussed and refined (but not yet adopted) by the SETI Permanent Study Group of the International Academy of Astronautics, on which several SETI League members serve. It would quantify on an integer scale of 1 to 10, based upon specific, measurable characteristics, the transmission risk associated with any Active SETI project, historical or proposed, or for that matter any other transmission of electromagnetic energy from Earth. The San Marino Scale is described at some length on that Study Group's website, (from the main menu at the left of each page, click on "Protocols;" then scroll down the page and look for the San Marino Scale link).

I urge all SETI League members to familiarize themselves with this new analytical tool. Whether promoting transmissions, or arguing for international sanctions, let us do the quantifiable risk/benefit analysis for which engineers are noted. A transmission with a San Marino score of 1 ('insignificant') through 3 ('minor'), I would suggest, scarcely warrants scrutiny. An impact score of 8 ('far-reaching') through 10 ('extraordinary'), on the other hand, should give even the most ardent Active SETI supporter pause.

Disclaimer: The opinions expressed in editorials are those of the individual authors, and do not necessarily reflect the position of The SETI League, Inc., its Trustees, officers, Advisory Board, members, donors, or commercial sponsors.

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