A post-detection policy (PDP), also known as a post-detection protocol, is a set of structured rules, standards, guidelines, or actions that governmental or other organizational entities plan to follow for the "detection, analysis, verification, announcement, and response to" confirmed signals from extraterrestrial civilizations. Though no PDPs have been formally and openly adopted by any governmental entity, there is significant work being done by scientists and nongovernmental organizations to develop cohesive plans of action to utilize in the event of detection. The most popular and well known of these is the "Declaration of Principles Concerning Activities Following the Detection of Extraterrestrial Intelligence", which was developed by the International Academy of Astronautics (IAA), with the support of the International Institute of Space Law. The theories of PDPs constitute a distinct area of research but draw heavily from the fields of SETI (the Search for Extra-Terrestrial Intelligence), METI (Messaging to Extra-Terrestrial Intelligence), and CETI (Communication with Extraterrestrial Intelligence).
Scientist Zbigniew Paptrotny has argued that the formulation of post-detection protocols can be guided by three factors: terrestrial society's readiness to accept the news of ET detection, how the news of detection is released, and the comprehensibility of the message in the signal. These three broad areas and their related subsidiaries comprise the bulk of the content and discourse surrounding PDPs.
Issues
Significance of transmission
There are two proposed scales for quantifying the significance of transmissions between Earth and potential extraterrestrial intelligence (ETI). The Rio scale, ranging from 0 to 10, was proposed in 2000 as a means of quantifying the significance of a SETI detection. The scale was designed by Iván Almár and Jill Tarter to help policy-makers formulate an initial judgment on a detection's potential consequences. The scale borrows heavily from the Torino Scale, which is used to categorize the hazard of impact of near-earth objects (NEOs). The IAA SETI Permanent Study Group officially adopted this scale both as a means of bringing perspective to claims of ETI detection and as an acknowledgement that even false ETI detections could have disastrous consequences, which should be mitigated.
A closely related metric is the San Marino Scale for quantifying potential hazard of deliberate transmissions from Earth. While the Rio scale rests on the relatively well-accepted science of the search for extraterrestrial signals (SETI), the San Marino scale seeks to bring objectivity to the reciprocal enterprise – that of human civilization sending transmissions that could be found by extraterrestrial civilizations (METI). The San Marino Scale was first proposed in 2005 and was adopted by the IAA SETI Permanent Study Group in September 2007.
Nature of detection
Despite widespread belief, there is no empirical knowledge concerning extraterrestrial life forms and civilizations. The implications of a detection of extraterrestrial life would vary greatly depending on the nature of that life, its location, and how human society reacts. Because of this lack of certainty, PDPs consider a variety of scenarios and the appropriate reactions. The formulation of a cohesive plan for a response to the detection of ETI would involve the development of scenario-contingent strategies for managing the discovery and its consequences.
Some scenarios have received more attention than have others. For example, while a sizable amount of work has been done to predict the consequences of a radio telescope detection of ETI elsewhere in our galaxy, very little such effort has been used to identify the consequences of discovering single-celled life forms elsewhere in the Solar System. Confirmation of such fossilized or living organisms on a nearby planet or moon could still have profound effects on individuals’ world-views and raise many ethical and practical issues.