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SpaceX’s hexagon heat shield tiles take on an industrial flamethrower

SpaceX’s next project is heating up — literally. CEO Elon Musk has revealed details about SpaceX’s Starship spacecraft project, aiming to create a next-generation space vehicle. The current test rocket is called Hopper and a prototype of it was recently constructed. Eventually, the aim is to use the Starship in the company’s ambitious plan to colonize Mars.

SpaceX decided to skip building a new nosecone for Hopper, Musk said, as it was no longer necessary. Instead, the company is building the original Starship vehicle. They are currently working on a way to protect the Starship from the extreme temperatures generated by re-entering the Earth’s atmosphere, and they have developed hexagonal heat shielding tiles for that purposes.

There is also a video showing the hexagon tiles in action, with nine of the tiles being put to the test by being blasted with heat by what are essentially flame throwers. The tiles are shown reaching the estimated orbital entry temperature of around 1,650 Kelvin (that’s a blistering 2,510 degrees Fahrenheit or 1,377 degrees Celsius) and are holding their integrity. The tiles managed to pass the test for the full duration that was required of them, indicating they could be able to protect Starship as it takes off and re-enters the atmosphere.

Testing Starship heatshield hex tiles

— Elon Musk (@elonmusk) March 17, 2019

The advantage of the hexagon shape is that it offers “[n]o straight path for hot gas to accelerate through the gaps,” according to Musk. Indeed, the hexagon is a useful shape which appears in nature such as in the honeycomb structures created by bees. The shape allows for a geometric array of identical cells with minimal wall area, leading to the honeycomb shape emerging naturally.

Musk offered more clues to upcoming SpaceX developments on Twitter, saying that the new hexagonal tiles will cover most of the windward side of the Starship as there is no shield needed on the leeward side. To cool difficult hotspots, transpiration cooling will be used for the hottest sections.

As for the details of the cooling system, Musk offered that “Transpiration cooling will be added wherever we see erosion of the shield. Starship needs to be ready to fly again immediately after landing,” adding that there will be “zero refurbishment” planned between one landing and the next takeoff.

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