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370 Active SETI Some of those involved in the interstellar communication debate dis- agree with the requirement for international consultations before we send signals intended to attract the attention of an alien civilization. As most of us recognize, there is not much point in expecting consul- tations about the radio, television, and radar signals that our civilization emits every day. The focal point of the debate is the exceptionally pow- erful signals like the one sent from Arecibo in 1974, signals that dra- matically increase our detectability. One suggested approach is to set a quantitative threshold for such consultations—for example, by requir- ing them for signals that exceed the power and duration of normal pulses from military or planetary radars. Almar proposed what he called the San Marino Scale, intended to quantify the potential hazard of transmitting messages into space. The main factors are the signal strength in relation to Earth’s normal back- ground radiation and the characteristics of the transmission such as information content, direction, and duration. He included the most subjective factor of all: intentions.* What would be our purpose in sending a communication to an alien civi- lization: to exchange scientific information, to describe ourselves, to propa- gate our values and cultures, to propose some course of action, or all of these? What does the human species want or hope for from contact? What do we wish to convey? We would need a clear vision of our own purposes. Physical scientists have tended to focus on sending and receiving scien- tific information. Nonscientists have other priorities. They want to describe human history, cultures, religions, values, and ways of organizing societies, as well as policy issues that we humans currently face. They want to ask the other civilization about the same things. As our message will be received by a society very unlike ours, it may be interpreted in ways quite different from what we intend. Rather than simply accepting our transmission as a vehicle for scientific information, the receiving party may exhaustively analyze the message from many points of view. What does the message (and the medium through which it was sent) imply about the knowledge and capabilities of the senders? Why did they send it? What are their intentions toward us? Many civilizations may be surprised by contact. Extraterrestrials, like us, might have both hopes and fears about this event. There is no perfect solution to this problem, as the knowledge, culture, and politics of the receiving society will be unknown to us. We might try Annex: Preparing What Should We Say?