SpaceX's Hexagon Tiles for Starship Heat Shield Pass Fiery Test

SpaceX is turning up the heat on its Starship spacecraft project, according to CEO Elon Musk. Literally.

In a series of posts on Twitter this week, Musk unveiled a tantalizing glimpse at a SpaceX test of the hexagonal heat shield tiles that will protect its Starship vehicle as it re-enters the Earth's atmosphere. SpaceX is developing Starship and its Super Heavy booster for deep-space trips to the moon and Mars.

"Testing Starship heatshield hex tiles," Musk wrote in a post Sunday (March 17). He also posted a short video of nine hex tiles being bombarded by flames.

Related: SpaceX Starship and Super Heavy Mars Rocket in Pictures

In subsequent posts, Musk said the heat shield test was a success, with the tiles surviving a full-duration re-entry profile. At times, the hottest parts of the tiles withstood temperatures of 1,650 Kelvin, Musk said. That's a whopping 2,510 degrees Fahrenheit (1,377 degrees Celsius)!

The hexagon is a great shape because it offers "no straight path for hot gas to accelerate through the gaps," Musk added. If tests show any heat shield erosion for Starship, SpaceX plans to add additional cooling systems to protect the spacecraft.

"Transpiration cooling will be added wherever we see erosion of the shield," Musk wrote. "Starship needs to be ready to fly again immediately after landing. Zero refurbishment."

While the hex tiles will protect the Starship vehicle during re-entry, don't expect the polygonal heat shield on the Super Heavy booster, Musk said. After all, he said, it's made of stainless steel.

"Super Heavy booster is stainless steel," he wrote. "Since it only goes to around Mach 8 or 9, moreover at high altitude, it needs no heat shield, not even paint."

SpaceX's Falcon rocket boosters, which the company is already reusing. The shield is made of aluminum-lithium and carbon fiber, Musk added. They have "low max temperature allowables."

SpaceX is developing its Starship vehicle as a next-generation spacecraft for deep-space travel. The vehicle as designed will stand 387 feet (118 meters) tall when atop its Super Heavy booster and carry up to 100 passengers.

The Hawthorne, California-based company has already signed its first passenger for Starship — Japanese entrepreneur Yusaku Maezawa — who has booked a flight around the moon.

SpaceX has also built a Starship prototype for suborbital-hop tests at its newest launch site near Brownsville, Texas. The first Starship "hopper" tests could occur this week.

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Tariq Malik

Tariq is the Editor-in-Chief of and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. In October 2022, Tariq received the Harry Kolcum Award for excellence in space reporting from the National Space Club Florida Committee. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. You can find Tariq at and as the co-host to the This Week In Space podcast with space historian Rod Pyle on the TWiT network. To see his latest project, you can follow Tariq on Twitter @tariqjmalik.