SpaceX Raptor engine test ends in a fiery explosion

A SpaceX testing stand at the company's McGregor, Texas facilities went up in flames during a test of its Raptor 2 engines on the afternoon of May 23. According to NASASpaceflight, the engine had an anomaly that caused vapors to seep out and lead to a secondary explosion. The news organization's livestream showed the engine shutting down before the fire started and eventually swallowed the stand in flames and smoke. 

SpaceX uses the Raptor engines for its Starship system's Super Heavy booster and upper-stage spacecraft. They use liquid methane and liquid oxygen as fuel, and they were designed to be powerful enough to be able to send Starship to the moon and Mars. As Gizmodo suggests, its gases mixing due to a leak or a similar anomaly could've caused the explosion, though SpaceX has yet to officially address what happened during testing. 

The company is currently preparing for Starship's fourth test flight, which is scheduled to take place on June 5, pending regulatory approval and barring poor weather or other factors that could delay the launch. This explosion likely wouldn't affect the flight's launch window. SpaceX's main goals for the fourth test flight are to make sure that the Super Heavy booster gets a soft splashdown in the Gulf of Mexico and to achieve a controlled entry of the Starship spacecraft. The company said it made several hardware and software upgrades to incorporate what it learned from its third flight test. Starship's upper stage reached space during that flight, but it burned up in the atmosphere upon reentry, while its Super Heavy booster broke apart in the final phases of its descent instead of softly splashing down into the ocean.