CEO Elon Musk says that SpaceX is about to begin the construction of “a much larger high bay” adjacent to the existing structure, an 82m (~270 ft) tall building used to complete assembly of Starship and Super Heavy boosters.
According to Musk, the newest addition to SpaceX’s arsenal of Starship production facilities will be located “just north” of an existing high bay, which measures approximately 30m by 25m (100′ x 80′). Most importantly, Boca Chica’s high bay is tall enough for SpaceX to use a bridge crane to stack 50m (165′) Starships and ~70m (~230′) Super Heavy boosters – far more efficient and protected than using wheeled or tracked cranes to assemble rockets out in the open.
Construction of the existing high bay began in May 2020 and was more or less complete by the start of 2021. The structure was truly finished in April 2021 with the installation of a heavy-duty bridge crane, though work continues to this day on what CEO Elon Musk has described as a bar and viewing area to be located at the top of the bay.
Musk’s assertion that the new facility will be “much larger” can be interpreted a number of ways. There’s a distant possibility that SpaceX will build a true NASA-style Vehicle Assembly Building like the colossal VAB used to fully assembled Saturn V and the Space Shuttle at Kennedy Space Center. For Starship, that would require a structure at least ~130m (~430 ft) tall – more than 50% taller than the current ‘high bay’.
More likely, Musk means that SpaceX will effectively be building a second similarly tall high bay but with far more usable floor space. The existing structure is large enough to fit four or far different Starship or Super Heavy ‘stacks’ at once, though SpaceX’s current setup appears to allow two or three vehicle sections to be stacked and worked on simultaneously. In his July 25th tweet, Musk implicitly noted that SpaceX does have a significant amount of mostly unused space that could be perfect for another assembly building directly north of the high and mid bays.
Generally speaking, SpaceX has a plot of land around 170m (~560′) by 190m (~620′) that’s currently half-used as a Starship scrapyard and overflow lot, but most of the space is empty. Even if SpaceX only turned half of that land into a sort of vertical Starship assembly line, it would still boost high bay floor space by at least a factor of five or six – and possibly 8-10x. With that much extra space enclosed in a permanent structure, it’s likely that this new facility could mark a new evolution in SpaceX’s ever-changing Starship factory.
Update: Elon Musk says that SpaceX’s second Starship ‘high bay’ will be “a little taller” than the first but have a “much bigger base” and multiple “gantry” (bridge?) cranes that will run the full length of the building.