SpaceX stacks Starship and Super Heavy booster for “wet dress rehearsal” test

SpaceX has fully stacked Ship 24 and Booster 7 for the third (and hopefully second to last) time. (SpaceX)

For the third time in three months, SpaceX has fully assembled Starship 24 and Super Heavy Booster 7 after another period of separate tests, repairs, and modifications.

Measuring around 120 meters (~390 ft) tall from ship tip to booster tail, the fully-stacked rocket is again the largest ever assembled. Compared to the Falcon 9 and Falcon Heavy rockets SpaceX currently operates, Starship is far larger. It’s also meant to be fully reusable, while the Falcon family – which expends its orbital upper stage – is roughly 80% reusable. If SpaceX can meet its technical goals, Starship could eventually cost around a magnitude less to launch than Falcon while carrying roughly 5-20 times more payload per launch. In short, it could revolutionize the cost of access to orbit.

Combined with orbital refilling, the ability to transfer propellant between Starships, reusable Starships could also radically exceed Falcon 9 or even Falcon Heavy’s expendable performance. But first, SpaceX needs to make sure that Starship can reach orbit at all.

Compared to Ship 20 and Booster 4, earlier prototypes that were also fully stacked a few times in 2021 and early 2022 before their retirement, Ship 24 and Booster 7 are closer to supporting Starship’s first orbital launch attempt. After their latest full-stack milestone, they could be just a few major tests away from being cleared for flight.

“According to CEO Elon Musk and a NASA official, the last major standalone test between Booster 7 and flight readiness is a full 33-engine static fire. Together, B7’s 33 Raptor 2 engines could produce up to 7600 tons (16.7 million lbf) of thrust at sea level, likely making Starship the most powerful rocket stage in the history of spaceflight.

A wet dress rehearsal is a routine test conducted before a rocket launch and is generally designed to simulate every aspect of a launch save for engine ignition and liftoff. Most importantly, that involves fully filling the rocket with propellant and passing all of the checks the same rocket would need to pass to be cleared for launch. The first full-stack WDR will test Starbase’s launch facilities just as much as Booster 7 and Ship 24.” – January 9th, 2023

The January 9th assembly of B7 and S24 confirms that the WDR will likely occur first, as conducting the first 33-Raptor Super Heavy static fire while fully stacked would unnecessarily risk the Starship. Ship 24 could fly on a future booster if B7 does not pass (or survive) proof testing. More likely than not, Ship 24 will be removed from Booster 7 after WDR testing, freeing Super Heavy for one last round of standalone static fire testing. If that testing clears Booster 7, Ship 24 will be reinstalled – possibly for the last time.

While hardware challenges continue to trump paperwork, an FAA launch license is another significant hurdle standing between SpaceX and Starship’s orbital launch debut. SpaceX and the FAA are in the middle of hammering out the details of such a license, which is partially contingent upon the completion of dozens of “mitigation” measures. Because Starship’s unprecedented size elevates the risk it could pose to local residents, it’s likely that that license is also contingent upon results from ground tests and will be one of the last gates to be lifted.

SpaceX has three windows that could be used for B7/S24 full-stack testing this week: two from 8am to 8pm CST on January 11th and 12th and one from 8am to 4pm on January 13th. CEO Elon Musk says that Starship could be ready for its first orbital launch attempt as early as late February or March 2023.

SpaceX stacks Starship and Super Heavy booster for “wet dress rehearsal” test
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