From a practical standpoint though (assuming that every nation decided to work together) how would such a mission work? We'd most likely need a generation ship

From a practical standpoint though (assuming that every nation decided to work together) how would such a mission work? We'd most likely need a generation ship, given that current estimates of max velocity is in the range of 0.5 to 0.8c. That means spending trillions of dollars and putting thousands of people in a ship in orbit, sending them off and most likely never seeing them again. But before that we'd want to send unmanned probes to: a) test out the propulsion and other systems b) scout the planets themselves, identify a good candidate But the probe itself would take 20-30 years to reach + 12 more to report back. Otherwise you're asking thousands to be explorers and guinea pigs for all this technology, with no guarantees about finding a habitable planet or coming back home. With something like the Mars mission you'd probably get volunteers without any family. People would be far more reluctant if it's a generation ship.