There's also a separate option that for profit corporations will undoubtedly exploit: the singularity is predicted for 2029, when machine general intelligence will surpass human intelligence. Subsequent advances in robotics will likely result in fully humanoid robots capable of self maintenance and repair by the 2040s or 2050s, which eliminates the need for food and water and places unrestricted timelines on operations. Human settlements are likely to be built by said robots because not a ton of people will be up for one way trips and the cost of sending robots is significantly lower.