A United Planet is required to do this and all we have to do is look at the DN (Do Nothing), oops, I mean UN.
Humanity needs to combine it's best resources working together in order to explore the stars and finance it.
To date, even America can't put a man in space anymore and relies on the Russkies.
Sad state of affairs...
Actually all it takes is the political will to do so - there is nothing which states that a “United Planet” has the political will to do anything other than force conformity on its citizens. Going into space is actually a risk, since that entails a loss of political control which is intolerable to such a bureaucratic nightmare.
Humanity in the form of Islam is busily killing everyone who is not them in some 20 odd wars currently underway. Eliminated the scourge and see if a better world could emerge.