SpaceX swapping out two engines on Starship SN9 prototype ahead of test flight

SpaceX's latest Starship prototype needs some maintenance work before it can take to the skies.

On Wednesday (Jan. 13), the Starship SN9 prototype performed three "static fire" tests in rapid succession at SpaceX's South Texas site, firing up its three Raptor engines while the vehicle remained anchored to the ground.

These brief burns were part of the preflight routine for SN9, which is being groomed for a high-altitude test. That big hop could have happened as soon as this weekend, had Wednesday's static fires gone perfectly smoothly. But there were apparently a few hiccups.

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"Two of the engines need slight repairs, so will be switched out," SpaceX founder and CEO Elon Musk said via Twitter early this morning (Jan. 15). 

Musk did not give a target launch date for SN9. But he did say, in another tweet, that it's "probably wise" to perform another static fire with the vehicle after the engine swap is complete. So a weekend launch for SN9 seems pretty unlikely.

SpaceX is developing Starship to take people and cargo to the moon, Mars and other distant destinations. The architecture consists of a 165-foot-tall (50 meters) spacecraft called Starship and a giant rocket known as Super Heavy. Both of these vehicles will be fully and rapidly reusable, Musk has said.

SN9's coming flight is expected to be similar to that of its predecessor, the three-engine SN8, which soared about 7.8 miles (12.5 kilometers) into the Texas skies on Dec. 9. That flight, the first high-altitude test for any Starship prototype, went extremely well, Musk has said, even though SN8 didn't stick its landing.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.