SpaceX prepares new Starship tank for explosive test after rapid construction

SpaceX is preparing for a potentially explosive Starship testing, this time featuring the unusual mini-tank pictured here on January 9th. (NASASpaceflight - bocachicagal)

Over the last few weeks, SpaceX’s South Texas Starship team has been making progress at a pace unprecedented even for the famously agile rocket company and is moving full speed ahead to kick off a new series of explosive tests as early as this morning.

Ever since SpaceX’s original Starship Mk1 prototype spectacularly failed during a November 2019 pressure test, the company has been rapidly rearranging and modifying the development schedule for its next-generation full-reusable rocket. Be it a side effect or coincidence, SpaceX effectively began closing its Florida Starship factory a week after Mk1’s demise and even shipped some of its Florida-built Starship hardware to Texas in recent weeks. However, most of the Florida workforce (up to 80%) was reportedly redirected elsewhere in the company, avoiding layoffs.

Some portion may have even moved to Texas and joined SpaceX’s Starship Boca Chica facilities. Given just how aggressively SpaceX has been expanding its local facilities and preparing new hardware for the next round of improved Starship prototypes, it seems quite likely that the South Texas outpost did indeed receive an influx of skilled workers. Most recently, the company has demonstrated its rapidly growing expertise in the bizarre art of building steel rockets en plein air by fabricating and integrating new tank domes and steel rings and then shipping the curious contraption to its nearby launch site in a matter of weeks from start to finish.

Although it’s difficult to determine the chronology of every single part of the mysterious new tank, it’s fairly safe to say that work on its structure began less than a week before SpaceX CEO Elon Musk tweeted a surprise update, indicating on December 27th that he was in Boca Chica, Texas working all night on “Starship tank dome production”.

In simple terms, the business half of SpaceX’s next-generation Starship upper stage and Super Heavy boosters are comprised of three main parts, shared by almost all launch vehicles. Both are rocket stages that must be as light as physically possible while supporting thousands of tons worth of supercool liquid oxygen and methane propellant. The majority of a simple rocket is ultimately a duo of cylindrical tanks capped by tank domes – also known as bulkheads. The bottom bulkhead of boosters and upper stages also serves as a mounting point for an engine section, where the vehicle’s rocket engines are attached to the rocket body in order to transfer their thrust throughout the rest of the structure.

SpaceX CEO Elon Musk says that Starship tank domes have turned out to be “the most difficult part of [the rocket’s] primary structure” to manufacture, thus explaining why he was apparently assisting the Boca Chica team all night on December 27th.

Starship Mk1 exploded on November 20th, 2019 during a nonflammable propellant loading test, a failure that unofficial videos have compellingly linked to the weld joint connecting the rocket’s upper tank dome to its cylindrical tank. That section of the rocket began leaking cryogenic propellant moments before the entire upper dome tore off the rest of the vehicle and launched hundreds of feet into the air.

All hail Baby Tank

In an apparent response to the unsatisfactory results of Starship Mk1’s manufacturing methods, SpaceX has rapidly initiated an already-planned upgrade of its Starship facilities and manufacturing methods in South Texas, taking delivery of a wealth of new tools over the last several weeks. Most recently, SpaceX’s latest step towards demonstrating that it has substantially improved manufacturing quality arrived in the form of a single propellant tank – the same diameter as Starship Mk1 but much shorter than any possible flight hardware.

Quickly nicknamed Bopper (short for Baby Starhopper) by locals and close followers, the miniature Starship test article came together at a truly spectacular pace. Comprised of two single-weld steel rings and two brand new tank domes, it appears that all four of the components were nothing more than parts and steel stock less than three weeks ago. The first sign of activity came around December 19th, when technicians began placing pressed steel sections onto a bulkhead (dome) assembly jig – used to precisely hold the pieces in the right shape and place as they are welded together.

A number of new single-weld steel rings were produced in Texas in the final weeks of 2019, pictured here on December 19th. (NASASpaceflight – bocachicagal)
SpaceX technicians also began assembling the first of two Starship test tank (‘Bopper’) domes around December 19th. (NASASpaceflight – bocachicagal)
Perhaps just 20 days or less after work started on the baby Starship tank, SpaceX transported the new hardware – made up of two domes and two rings – to a nearby launch (and test) pad. (NASASpaceflight – bocachicagal)

Incredibly, aside from taking less than three weeks to go from miscellaneous parts to an assembled Starship tank delivered to the test site, SpaceX technicians appeared to finish stacking and welding its two halves (each a ring and a dome) perhaps a handful of hours before it was lifted onto a transporter and driven to the launch pad.

As of dawn, January 9th, the welds joining the two halves of the mini Starship tank were visibly incomplete and in-progress. Note the bright point and unfinished line near the center, indicative of active welding. (NASASpaceflight – bocachicagal)

Even for SpaceX, moving a prototype from factory to test site hours after its primary structure was welded together represents an almost unfathomably fast pace of work – truly unfathomable in traditional aerospace. Whether or not such a pace of work is smart, sustainable, or worth it remains to be seen, but SpaceX is nevertheless on track to pressure test its new mini Starship tank as early as this morning, potentially resulting in another spectacular overpressure event (i.e. explosion).

If the tank survives up to or beyond the pressures SpaceX has designed it to, it’s safe to say that the next full-scale Starship prototype could come together far sooner than almost anyone might have expected.

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Eric Ralph: I write about space, among other things.
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