SpaceX has launched the upgraded third version of its Starship rocket for the first time, though the test launch did not go perfectly for Elon Musk’s spaceflight company.

The 407-foot rocket — the most powerful ever built — lifted off from SpaceX’s company town Starbase, Texas, at 5:30 p.m. local time. Just a few minutes later, the upper stage ship separated from the Super Heavy booster and continued on into space.

The booster pitched away from the Starship vehicle and headed back to Earth, where it was supposed to perform a simulated landing in the Gulf of Mexico. But the booster’s engines did not properly re-ignite for the sustained burn that is meant to deliver it back to the launch site. The booster then tumbled down to the water, where it likely exploded.

Starship, meanwhile, lost one of its six Raptor engines as it ascended into space. The ship was still moving through space on its way to the Indian Ocean at the time this story was published.

While it didn’t go exactly according to plan, this was an important test launch for SpaceX. It was the first real shakedown of the upgraded Starship V3 hardware, which has been in development for months. The company was also testing out an all-new launchpad at Starbase that it’s been developing and building for years.