Interstellar voyages
I think it is likely that we will be able to explore other star systems some time in the future, albeit not that soon. However this will not be in a search for an alternative planet for humans to live on. It won’t be the discovery of warp drive, nor an intrepid band of misfits who escape a tyrannical earth government in a starship that they knocked up in someone’s garage.
I think it will only be possible after we have mastered the technologies of space settlement within the solar system, as the distances and journey times are so long. Such an approach is sometimes called ‘generational ships’. The idea is that first you master space settlement, with a closed ecology, and then you just move your settlement towards another star.
What are the challenges?