I'm probably putting these thoughts to words just to potentially walk myself to an answer, but when it comes to life outside of the earth, why are we limiting ourselves to earthlike planets?  Yes they will hold the highest potential of harboring intelligent life at least as we know it, but even "life as we know it" is so limiting. Whose to say life can't evolve and prosper on any planet with an atmosphere and surface, or subterranean ocean, which is essentially the same scenario.  Maybe liquid methane acts as a perfect replacement to water to some alien species.  Even if we are 100% certain we've found intelligent life on a distant planet, it's not like we can even communicate, let alone explore it any time soon with such vast distances between 
us.  

Why not strive to prove some form of life can exist off the earth, on planets or moons we can reach?  Moons like Titan hold a huge potential for that IMO