When SpaceX鈥檚 Starship rocket launched for the first time in 2023, it destroyed its launch pad in an explosion similar to a volcanic eruption that sent huge chunks of concrete high into the sky. Understanding the blast in detail could help us design more robust launch and landing pads for future missions to the moon and Mars.
鈥淚t was eye-opening to us that launch pads could explode so violently,鈥� says at the University of Central Florida. Metzger and his colleagues studied videos and debris samples from the test flight to figure out what went wrong.
They found that the explosion could not be explained simply by the exhaust and fire from the rocket engines, and must have been strengthened by an additional factor. 鈥淭hese were giant pieces of concrete travelling at 90 metres per second, making splashes in the ocean that were 20 metres high,鈥� says Metzger. 鈥淚f it was just the gas forces of the rocket exhaust, it would not have accelerated these large chunks to that velocity.鈥�
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The researchers found that what happened was similar to a type of volcanic eruption in which pressure builds up beneath a plug called a caprock, which eventually explodes. In this case, the caprock was the concrete launch pad. The pressure was caused not only by the hot gas from the rocket engines, but also because the groundwater underlying the pad turned to steam and expanded, blasting the concrete upwards.
In the aftermath of the blast, a fine drizzle of small debris particles settled over the surrounding area, lofted more than 10 kilometres away from the launch site. The researchers examined samples of this debris and found that the particles were mostly sand from the ground beneath the launch pad.
鈥淚n general, this had little environmental or overall health impacts,鈥� says Metzger. 鈥淔or context, if you threw a handful of sand at somebody, it might get in their eyes, but the sand falls 鈥� it doesn鈥檛 stay suspended like dust might, so you don鈥檛 end up breathing it in.鈥�
This sort of explosion was unusual because nearly all launch pads have built-in mitigation features, such as flame trenches or systems that inject huge amounts of water onto the pad. SpaceX鈥檚 pad was not equipped with any of this. SpaceX did not respond to a request for comment.
鈥淭hey knew that this might be a risk, but the goal was to test the rocket and the launch pad was secondary,鈥� says at Michigan Technological University. 鈥淣ow they鈥檝e installed a big steel plate, they鈥檝e installed a water deluge system, so this failure is not likely to happen ever again.鈥� Indeed, SpaceX鈥檚 two following tests did not blow up the launch pad.
Insights into this explosion should help researchers design better launch pads in the future, says Metzger.
鈥淭his really underlines the need for the right landing and launch infrastructure on the moon and Mars if we want to have a permanent presence there,鈥� says van Susante. 鈥淚f you go to the moon and you damage your rocket engines like they did here, then you can鈥檛 get back.鈥�
arXiv
