SpaceX hopes to send astronauts to the surface of Mars aboard its currently-under-construction Starship rocket as early as 2024. The company estimates that the monumental vessel will enter the Martian atmosphere at around 16,777 mph, and CEO Elon Musk recently revealed that he plans to prevent it from disintegrating with the world’s first “regenerative heat shield,” which, Musk also recently revealed, is already being tested.
Friday, Musk tweeted the above video of what appears to a prototype version of the “stainless-steel sandwich” shield that he described during his recent interview with Popular Mechanics. The footage shows a white-hot slab of metal being blasted by an array of flamethrowers taking it to temperatures that are about as hot as lava.
“Testing metallic heat shield at 1,100C (2,000F),” wrote Musk.
He didn’t elaborate as to exactly which materials he was testing in the video, but he described Starship’s planned heat shield as being made of two layers of stainless steel that would be cooled by water or cryogenic rocket fuel. Stainless steel can be heated up to 2,786 degrees Fahrenheit before it begins melting, that’s a vast improvement compared to traditionally-used aluminum, which melts at roughly 1,221 degrees. But
That’s all very cool and interest there’s still a lot of stress-testing to be done.
Spacecraft reentering the atmosphere are estimated to experience temperatures as hot as 3,000 degrees, according to NASA so the prototype has increasingly more intense heat tests in the near future. But Musk plans on using a concept known as transpiration cooling to keep it the shield from reaching dangerous temperatures.
Starship’s stainless steel heat shield will be peppered with tiny holes to allow super-cold liquids, like liquid methane to pass through it. As coolant runs through the shield it absorbs a part of its energy and will hopefully prevent serious heat damage.
It’s unclear if SpaceX will attach the prototype shield to the currently damaged Starship “Hopper”. But seeing as the test vessel will only be completing a series of suborbital, “hop” tests it’s likely that SpaceX will save the shield for Starship’s first atmospheric reentry test, which could happen as soon as 2022.