There is no way to prevent attempts at contact so they should be official.  There is no way for us to attempt to prevent everyone in the planet from trying to contact aliens so the attempts might as well be done officially. There are more than 6 billion people on Earth, we cannot control their actions or keep an eye on them all. If we had no official messages going out then we would be allowing private individuals to monopolize the message which could have consequences if there ever is contact as a result of these attempts1. At the same time we can't just turn off all our communication signals. We have been broadcasting our radio and television shows, mobile phone conversations etc. for decades, how would we just shut it all off and make sure nothing leaks further out to space? It is therefore better for governments who are at least the representatives of their people to be controlling the message by themselves attempting to contact extraterrestrial life. 1  "&gt;Drezner, Daniel, 'How do you say "realpolitik" in Klingon?' ForeignPolicy.com, 25th April 201