When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. SpaceX's Starship rocket launches on its fourth fully integrated test flight, on June 6, 2024. (Image credit: SpaceX) 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." The stainless-steel Starship consists of two elements: a first-stage booster called Super Heavy and a 165-foot-tall (50 meters) upper-stage spacecraft known as Starship. A stacked Starship is the biggest and most powerful rocket ever built. It stands about 400 feet (122 meters) tall and generates 16.7 million pounds of thrust at liftoff — nearly twice that of the Space Launch System (SLS), the rocket for NASA's Artemis moon program. SLS is expendable, but Starship is designed to be fully and rapidly reusable. Indeed, SpaceX plans to land Super Heavy back on the launch mount after each liftoff, enabling quick inspection, refurbishment and relaunch. SpaceX believes that Starship's combination of brawn and efficiency will finally bring Mars settlement — a long-held dream of Musk's — within humanity's grasp. Get the Space.com Newsletter