Enlarge this image At nearly 400 feet tall, Starship is the largest rocket to ever fly. SpaceX hopes it can become a vehicle for interplanetary travel. SpaceX hide caption toggle caption Elon Musk Unveils SpaceX's New Starship, Designed To Fly To The Moon, Mars And Beyond The stakes could not be higher, at least to hear SpaceX CEO Elon Musk speak about the mission. "Eventually the Sun will expand and destroy all life," Musk said, standing before the giant rocket about a year ago. "It is very important – essential in the long-term – that we become a multi-planet species." Musk hopes Starship will provide a critical step to becoming multiplanetary, by allowing large payloads to be carried into orbit for cheap. His goal is for Starship to someday transport the first people to Mars. Sponsor Message SpaceX also has a business interest in seeing its mammoth rocket fly. Starship could be used to launch large numbers of the company's internet-providing "Starlink" satellites. Starlink is seen as a key part of SpaceX's future, and Starship would allow the network to rapidly grow, says Tim Farrar, the president of TMF associates, a telecom consulting firm. YouTube But Starship is unlike any other rocket, and SpaceX acknowledges that the first test flight will be extremely risky. That launch attempt is set to take place during a 150-minute window that opens at 8 a.m. Eastern on Monday, April 17. When the company recently posted its timeline for the flight, it replaced "liftoff" in its mission timeline with two words: "excitement guaranteed." Starships were meant to fly Standing at nearly 400 feet tall, Starship is made of gleaming stainless steel, an unusual choice in a business where every pound of weight matters. In fact, SpaceX started out looking at advanced, lightweight composites for Starship, Musk told the Space Studies Board of the National Academies in 2021. But he quickly realized that steel was cheap, abundant, and most importantly, incredibly tough. It could hold cryogenic rocket fuel and tolerate the grueling heat of re-entry better than other materials. Sponsor Message "I'm a big fan of stainless steel," he joked. "Stainless steel and I should get a room or something."