How close does it have to be?
Well, they've just discovered a smaller planetary system (I almost said "solar system," but I think that's reserved to our own star.), using a nifty new technique called microlensing.
They figure that, given how quickly they found the two gas giants in that planetary system, they're going to find a lot more. Only problem-- that star is 5000 light years away, which means that live television newscasts reporting about Enoch (Methuselah's daddy) inventing the eyed needle are just now getting to that star.
But how far is close enough?
Let's just say we manage, using RamJets, light sails, or (most likely) nuclear pulse propulsion, to get a starship to average 10% of c. That would take us about 40 years to reach our closest neighboring star, Proxima Centauri. Hm. A 30 year old man would arrive at aged 70, and would find that he had no one to yell at to turn that damned music down, because there's nothing there.
Well, we're already planning to send one kind of exploratory craft or another to Alpha Centauri B.
Well, whoopie. Time to put some men and women on a ship, and send them. Why? Because Longshot and Daedalus both will take ~100 years to get there, plus another 4.5 years to report back.
Bull puckey. Longshot's expected payload is 30 tons. Double it --triple it--- and send humans.
Back to that original question: how close (by which I mean "how short a time") does it have to be? 5000 years is too far. 30 years or so is okay. Now we're bargaining. 200 years?
Surely what with cryogenic sleep, embryonic storage, robot technology, and a skeleton crew, we could do a few generations?
Would you do it?
Are you thinking that we should?
Get this thing moving. We don't have all that much time.