On Tuesday, SpaceX tested its Super Heavy rocket for about 12 seconds, making it the massive booster’s longest firing time to date. The test, which fired 11 of the 33 Raptor rocket motors, came as SpaceX continued work on an orbital launch attempt of this Super Heavy first stage and the Starship’s upper stage.
Earlier this month, SpaceX fired 14 Raptor engines at this booster for a few seconds, so Tuesday’s test failed to set a new record for the number of engines tested. However, this “long duration” firing is the longest period that so many Raptor engines have fired at once.
So what’s going to happen now? The path to orbit for SpaceX and its Starship launch system is unclear. Previously founder of SpaceX said Elon Musk the next step was to fire a subset of Super Heavy’s engines for about 20 seconds to test the autogenous pressure control. This method of pressurizing fuel tanks uses gases generated onboard the rocket instead of a separately charged, inert gas such as helium.
Tuesday’s test may have been a slightly shorter version of this autogenous pressure test – 12 seconds instead of 20 – or it could have been something else. The company is taking an iterative design and development approach to the Starship vehicle and its Super Heavy first stage, so its test plans are fluid, similar to the rocket’s cryogenic propellants.
In all likelihood, SpaceX still has some key tests to complete before launching the combined Super Heavy rocket and Starship upper stage from the company’s Starbase facility in South Texas. It is expected that SpaceX will conduct at least a short-term test of all 33 Raptor engines at once to gain confidence in the totality of the complex plumbing to fuel and pressurize the rocket’s propulsion system. Then the Starship’s top stage is stacked onto Super Heavy and the combined vehicles must complete a wet dress rehearsal.
What seems clear is that SpaceX is maturing its approach to working with the Starship architecture as recent tests, including Tuesday’s, have ended without apparent failures.
After all technical preparations are complete, SpaceX must also obtain a launch license from the Federal Aviation Administration, which is ongoing but has yet to be completed. While it remains theoretically possible that Starship will make its orbital launch attempt in December, the test flight is more likely to take place in early 2023.