Look at this table
. The closest arrival date for a targeted interstellar message is the Morimoto - Hirabayashi Message, which arrived to its destination, Altair
, in 2017. Altair is located just 16.7 light years away.
So a response could arrive from Altair at best in the year 2034 (16 years from now). That is if we assume there is life there which is very improbable considering what we commented here
about O, B and A type stars habitability (Altair is an A-type). We have also to assume that life is intelligent there, which is also highly unlikely in particular for this system if we consider that Altair is only 1.2 billion years old (no time for any kind of conceivable evolutionary track to intelligence in my opinion). Also we have to assume that they want to answer to us. And even in that case the response would arrive in 2034 if and only if they inmediatly responded (do you think we will respond in less than a year if this ever happenes to us? with all the political, diplomatic and military issues humanity would have to debate to make sure there is consensus in the content of the message).
So I would say that this is just having faith.
So what's the next chance we have? Well, the RuBisCo Stars project sent a radio message to Teegarden's star
(which is just 12.6 light years away from us) in November 2009 so an inmediate response would be received here around 2035 (a year after Altair's response). 2035 is in 17 years. That's good. I think this is a better candidate because the star is an M-type star, although we haven't detected any planet yet in that system (besides huge efforts).
RuBisCos stars project also aimed to L1159-16
, low mass star some 14 light years away. An inmediate response would arrive to Earth in the year 2038 at least (20 years from now). But is a bad candidate considering the fact that L1159-16 is a flare star. X-ray activity and violent variability is a very likely inhibitor for life generation. I wouldn't bet for this star.
All these targets yield a response in less than 2038 in the best case scenario. But we have still not detected a single planet in the three cases. And they are not very promising as habitable systems. Even if they were promising systems for habitability the possibility that they have life, life is intelligent in nature, they are willing to answer and they answer inmediately is just puny. Even then, if all of that is acomplished, you still have to think that receiving an aswer from one of this would basically mean that there are intelligent species all around and close to home. It is very very unlikely that we find intelligent life just in the first star we try to message. Absurdly unlikely in my opinion.
The next possible response will come from Gliese 581
in 2050 (always considering the best case scenario). And next responses are for the next century in the best case scenario still.
So hoping for a reply from an extraterrestrial intelligence in the next 10-20 is been the most optimistic the math allows you to be. In my opinion the only hope is to get a signal, but not as a reply but as an actual first message from a civilization a thousand years ago from another part of the solar neighbourhood. Even then I consider optimistic the idea of another civilization in our entire galaxy so maybe we will never get an actual answer at all.