Elon Musk has been talking about his plans to colonize Mars for years, most notably at a September 2016 conference in Mexico, at which he said that he would need just 40 to 100 years to create a self-sustaining civilization of 1 million people there.
At the time, he also said that an individual trip would cost around the median price for a house in the United States: $200,000. The Big Falcon Rocket is still unbuilt but is crucial to that goal, as it can carry between 100 and 200 passengers — far more than established rockets using what he calls “traditional methods.” At the time of the Mexico conference, The Verge’s Loren Grush pointed out that Musk had yet to answer some of the biggest questions about what a Mars trip would entail.
The first and biggest is that, so far, there is no plan in place to protect Mars voyagers from dying of radiation before they even get there; nor do we really even know very much about what it would entail to keep all the muscles inside a typical human body from atrophying over the course of an 80-day trip in zero gravity.
There is no plan for what the housing on Mars would look like, or what, say, would happen to an embryo if it gestated entirely in one-third gravity. We have no idea what kind of cross-contamination would result from swapping microbes between Mars and Earth, and we also don’t know if Musk is still planning to artificially raise the temperature on Mars and give it a thicker atmosphere to allow the flow of water. (At the 2016 press conference, he said he would leave many of these questions “up to the decision of the people on Mars.”)