SpaceX is perhaps best known for its reusable Falcon 9 rocket, the same variety that will be lofting astronauts into outer space from American soil on Wednesday for the first time since the Space Shuttle era almost a decade ago. But another of SpaceX’s projects that appears to be gaining steam is Starship, a space vehicle crafted out of shiny stainless steel that CEO Elon Musk hopes will one day play a part in interplanetary travel.
One of the questions that comes up a lot is why SpaceX chose to use stainless steel as Starship’s primary build material, as its weight-to-strength ratio leaves a lot to be desired. This is the primary reason why most modern rocketry uses some form of aluminum alloy, as it’s both lighter and cheaper to send to space. But as it turns out, the answer to that is fairly simple: temperature tolerance.
The whole idea behind Starship is to be an interplanetary vehicle, and this means that it’ll be subjected to both freezing and scorching temperatures as it ascends from and descends into planetary atmospheres, not once, but twice. As it turns out, this is where stainless steel shines, as it has a particularly good tolerance to temperature variances that many other materials simply can’t compete with.
When starship enters Mars’ incredibly thin atmosphere, it will do so in such a way that the amount of drag is increased to slow the vehicle down as it falls. With drag comes heat, and in this case, more heat than even stainless steel can handle. SpaceX aims to cool Starship’s descent with a liquid methane pump underneath the Starship’s surface, which will essentially fight back against the heat similar to how humans sweat in the heat.
As of now, the Starship prototypes aren’t much to write home about, but SpaceX intends to improve the manufacturing process as it goes to eventually build what some might call one of the most ambitious interplanetary space vehicles of its time. It should be interesting to see how this pans out…