I was reading this and have to say I agree with the comments by Bob Greenwade and yaz.
It's pretty sound to consider that anyone out there intelligent enough to find the meti messages sent by the population would be intelligently evolved enough to at the very least be on our own level but most likely a lot more advanced. If they are space bound then they're in orders of magnitude more advanced and will be exactly as yaz puts it:
Have you read this before mate, could be up your street.
![Smile :) :)](/styles/default/xenforo/vbSmilies/Normal/smile.gif)
http://sethbaum.com/ac/2011_ET-Scenarios.pdf