I think that, before colonizing other planets, we should start by realizing that Earth can easily sustain human kind for the foreseeable future, given some pretty modest tweaks to our way of life (compared to "going multi-planetary" that is). If we start valuing quality over novelty, stop eating animal-based foods and re-organize to live closer to where we work, we can stop the consumption and that is taxing our ecos…
As for wealth redistribution, I may be pessimistic, but how likely are you to give up 3/4 of your salary post taxation to someone you aren't related to and don't know through some kind of redistribution plan?