SpaceX recently launched their most powerful rocket yet: the Starship. At a whopping nearly 400 feet tall, this majestic feat of engineering blasted off, soared to an altitude of about 25 miles, then promptly exploded in an equally majestic fashion. A second look at the launchpad revealed considerable damage, too—far more than was initially anticipated. While the launch is considered a success, it's left a lot of people scratching their heads. What happened? Why did the Starship blow up, and what happened to the launch site?
The test of the Starship was to see if it was capable of launching at all. In that sense, it passed the test. The launchpad, however, didn't fare nearly as well.
In the words of Phil Metzger, a scientist at the University of Central Florida who has worked for NASA specifically on launch pad research, the failure of the launchpad was “catastrophic.” While they may not seem like it at first glance, launchpads are as complex and carefully engineered as rockets are. The launchpad used by the Starship appeared to have failed due to the heat and force generated by the rocket engines. This charred support structures, blasted a crater in the ground, and sent chunks of concrete and lots of dust flying into the surrounding area.
As gasses were expelled from the engines, they were forced into cracks in the concrete caused by the heat. These gasses caused the cracks to expand, eventually sending chunks of the launchpad flying. Most of this debris landed in an area designated as a hazard zone. Unfortunately, the damage to the launchpad was so extensive, it also damaged the soil beneath the launchpad. Since dirt doesn't fracture like concrete does, this didn't result in large chunks of debris that stay within the hazard zone—instead, it scattered dust for several miles, exposing the surrounding area to an increased risk of health and ecological problems.
A design for a water-cooled launchpad that would've theoretically been better able to cope with the heat was underway, but not ready in time for the launch. This design would've used a steel plate equipped with channels which would direct cool water throughout the pad. This would spread out the heat from the rocket engines, preventing the kind of thermal damage seen on the concrete launchpad.
While the failure of the launchpad and the potential health and ecological ramifications are big deals in their own right, they don't really explain the big question on everyone's mind: What made the rocket blow up? Or, to put it in SpaceX's terms, undergo a “rapid unscheduled disassembly before stage separation?”
For that, we need to look at the Starship's flight termination systems. Believe it or not, the explosion wasn't actually the issue. At liftoff, some of the rocket's engines didn't fire up when they should have. The Starship's upper stage and booster didn't separate, either. This precipitated an approximately minute-long tumble, after which the rocket's flight termination system kicked in. That's what ultimately triggered the explosion.
A flight termination system, or FTS, is a safety and licensing requirement for space launch vehicles and missiles. These are designed to protect ground personnel and people occupying surrounding areas. They're made up of a receiver, Safe & Arm Device, and termination system.
When something goes very wrong, safety personnel send a signal to the receiver to engage the FTS. The receiver picks this up and transmits it to the Safe & Arm Device (or SAD), which then arms and engages the termination system. The termination system then causes the missile or rocket to become unstable and go into a self-destructive phase of flight. In essence, it's a system that sacrifices the vehicle or missile in order to protect the people below.
While it's not desirable for a rocket to explode, even during a test, it's often better than the alternative. This launch was considered a success because the rocket managed to lift off and clear the launchpad's 500-foot tower. However, it appeared that several of its engines didn't kick on when they were supposed to, which most likely triggered an automatic signal to the FTS. This caused the Starship to explode rather than potentially veer off unpredictably and crash down to the ground below.
What's next for the Starship? With this test completed, the next step is to figure out what went wrong, why, and how to fix it. Right now, ground infrastructure issues could create some considerable delays for the company. It's not yet known just how extensive the damage is, what'll be required to repair it, or to what extent it's repairable.
SpaceX is contracted to perform a key role in the Artemis III project. This involves SpaceX's Starship human landing system meet a team of astronauts riding in an Orion on a Space Launch System vehicle, then bring them to the lunar surface and back. It's currently uncertain whether this will be able to take place in 2025 as planned.
While the test of SpaceX's Starship was successful, there are still several bugs to iron out. A launchpad design that's better able to cope with the heat will be necessary in the future, and SpaceX needs to figure out why some of the Starship's engines didn't fire when they should have. All things considered, the explosion itself wasn't the issue—it was the result of the FTS doing its job.
