SpaceX launches 11 engines as it prepares huge rocket for orbital test

Enlarge / SpaceX's Booster 7 undergoes a static fire test with 11 engines Tuesday in South Texas. SpaceX

On Tuesday, SpaceX tested its Super Heavy rocket for about 12 seconds, making it the massive booster's longest firing time yet. The test, which ignited 11 of the 33 Raptor rocket engines, took place as SpaceX continues to work on an attempted orbital launch of this Super Heavy first stage and its Starship upper stage.

Earlier this month, SpaceX fired 14 Raptor engines on this booster for a few seconds, so Tuesday's test didn't set a new record for the number of engines tested. However, this "long duration" firing is the longest period of time that so many Raptor engines have been fired at once.

What happens now? The path to orbit for SpaceX and its Starship launch system is unclear. Previously, SpaceX founder Elon Musk said the next step was to fire a subset of Super Heavy's engines for about 20 seconds to test autogenous pressurization. This method of pressurizing fuel tanks uses gases generated onboard the rocket rather than a separately charged inert gas such as helium.

Maybe Tuesday's test was a slightly shorter version of that autogenous pressurization test (12 seconds instead of 20) or something else. The company takes an iterative approach to the design and development of the Starship vehicle and its Super Heavy first stage, so its test plans are fluid, much like the rocket's cryogenic thrusters.

In all likelihood, SpaceX still has some key tests to perform before the combined launch of the Super Heavy rocket and Starship upper stage from the company's Starbase facility in South Texas. SpaceX is expected to conduct at least one short-duration test firing of all 33 Raptor engines simultaneously to gain confidence in all of the complex plumbing to power and pressurize the rocket's propulsion system. Next, the Starship upper stage will be stacked on top of the Super Heavy, and the combined vehicles must perform 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 been completed without any obvious failures.

After completing all of its technical preparations, SpaceX must also obtain a launch license from the Federal Aviation Administration, which is in progress but has not yet been finalized. Although it remains theoretically possible that Starship will make its orbital launch attempt in December, it is increasingly likely that the test flight will take place in early 2023.