Enlarge / A drone shot looking down on SpaceX's Super Heavy booster during a test-firing of its 33 Raptor engines Monday. (credit: SpaceX) It's unclear yet how long SpaceX's workhorse Falcon 9 rocket will remain grounded as engineers investigate a rare launch failure last week, but the next test flight of the company's next-generation Starship vehicle appears to be on track for liftoff next month. On Monday, SpaceX test-fired the 33 Raptor engines on the Starship rocket's Super Heavy booster at the company's Starbase facility in South Texas.