I think this plan is an imperative to human survival and advancement as a sentient species (in the arenas of culture and overall knowledge). I just hope enough people in high places hold the same necessary long term vision that you are capable of understanding.
Here is a worst case scenario if we don't even try to take your hypothetical pilgrimage into colonizing space...
2016 - Second series of manned moon landings
2020 - Establishment of permanent lunar colony.
2021 - Congress turns down allocation of funding to NASA to maintain/upgrade advance orbital asteroid warning system.
2022 - Congress closes down lunar colony as they can't imagine wasting anymore taxpayers' money on that endeavor when that money needs to be wasted on each individual congressman and woman's own personally staked pork belly projects.
[2027 - First manned landing on Mars and Establishment of Mars colony never occur. Science for science sake?! Pshaw!
say the conservative critics. "There is no immediate profit for me as an individual for me to care about the potential benefits from that," so sayeth the near science illiterate Congressional naysayers.]
2030 - Unnoticed Extinction level Event asteroid hits somewhere (ironically) in between the Euphrates and Tigris Rivers on Easter morning (of all days).
EFFECTIVELY? The End to our collective story!