Musk Gives an Update on When a Mars Colony Could be Built

"The objectives for the first mission will be to confirm water resources, identify hazards, and put in place initial power, mining, and life support infrastructure. A second mission, with both cargo and crew, is targeted for 2024, with primary objectives of building a propellant depot and preparing for future crew flights. The ships from these initial missions will also serve as the beginnings of the first Mars base, from which we can build a thriving city and eventually a self-sustaining civilization on Mars."