An interesting aspect of this is that the same
requirement exists to have a viable colony on Mars, or
the Moon. Wherever we go we need to settle at least 1,000 and preferably 10,000 people. Add this to the requirement for artificial gravity to prevent health problems: Since humans cannot withstand more than 2 rev/min a rotating spacecraft has to be at least 1/2-kilometer in diameter. NASA did not build such a monstrosity in low-earth orbit let alone one that could blast off to another planet carrying 10,000 people. What is the crew compliment for ISS Alpha?

We are a loooonnngggg way from being a spacefaring
civilization. Hopefully we can do something to expand our seemingly recreational forays into space. Gotta think about that one!