The top of SpaceX’s Mk1 Starship appears to have blown off during a pressure test of the prototype rocket. Livestream cameras captured footage of the explosion.

The company’s CEO and founder Elon Musk downplayed the incident, replying to a Twitter comment about what this means for the spacecraft’s development by saying, “This had some value as a manufacturing pathfinder, but flight design is quite different.”

SpaceX said: “The purpose of today’s test was to pressurize systems to the max, so the outcome was not completely unexpected. There were no injuries, nor is this a serious setback.”

Starship is planned to be used for services to the Moon and Mars. On a conference call organized by NASA earlier this week, SpaceX president and COO Gwynne Shotwell stated that the company could land a Starship craft on the Moon as early as 2022.

SpaceX had suffered a failure of a commercial Falcon 9 launch in 2016 as well as the failure of a test of its crewed Dragon spacecraft earlier this year.