Elon Musk has identified the likely cause behind the dramatic explosion of SpaceX’s Starship upper stage during ground testing in Texas. According to Musk, a pressurized tank known as a COPV (composite overwrapped pressure vessel), located in the rocket’s payload bay, failed during the static fire prep, triggering a massive fireball that lit up the night sky.
This Starship prototype was being prepared for Flight 10, following incremental progress made with Flight 9 earlier this year. 
While Flight 9 was the first upper stage test to reach space and perform a successful engine shutdown, it still failed during atmospheric reentry, losing control and skipping key tests such as the heatshield and landing simulation.
The new explosion is a step back for the program. Still, Musk’s comments suggest the issue may be straightforward to fix. “Preliminary data suggests that a nitrogen COPV in the payload bay failed below its proof pressure,” he posted. These tanks are essential to maintain tank pressure with inert gases during flight, preventing structural collapse.
Footage of the explosion corroborates Musk’s claim, showing flames bursting from the top of the rocket – where the payload bay is situated. The real challenge may now be repairing the damaged ground infrastructure, which took the brunt of the blast. This could delay further testing more than the rocket itself.
SpaceX had been preparing the vehicle with engine reignition trials skipped during Flight 9, indicating this was a crucial milestone toward reusable flight. If the COPV issue is isolated and quickly addressed, the ambitious Flight 10 might still take off in the near future – assuming ground facilities can be brought back online swiftly.
As with all SpaceX endeavors, failure is seen as part of the iteration cycle. But with each explosion comes both a step back and an opportunity to refine one of humanity’s most audacious space programs.