SpaceX's Starship megarocket will start flying Mars missions just two years from now, if all goes according to plan. "These will be uncrewed to test the reliability of landing intact on Mars. If those landings go well, then the first crewed flights to Mars will be in 4 years," SpaceX founder and CEO Elon Musk said via X on Saturday evening (Sept. 7), in a post that announced the bold new target timelines. (Earth and Mars align properly for interplanetary missions once every 26 months.) "Flight rate will grow exponentially from there, with the goal of building a self-sustaining city in about 20 years," Musk added in the same post. "Being multiplanetary will vastly increase the probable lifespan of consciousness, as we will no longer have all our eggs, literally and metabolically, on one planet."