SpaceX’s next Starship prototype is already closing in on its first tests

SpaceX technicians work to flip Starship SN4's last major subsection, a sign that its installation could be just a few days away. (NASASpaceflight - bocachicagal)

Continuing a trend of massive steel rockets built in a matter of days and weeks instead of months, SpaceX’s next Starship prototype is already closing in on its first tests.

SpaceX’s newest vehicle is set to pick up where the third full-scale Starship prototype – coincidentally known as SN3 – left off after operator error lead to its premature destruction on April 3rd. Now a pile of scrap metal, that ship only made it partway through cryogenic proof testing when its upper tank – almost fully filled with chemically-neutral liquid nitrogen – toppled over and pulled the rest of the prototype with it. With (hopefully) improved test procedures, Starship SN4 is now set to carry that torch forward.

Following the late Starship SN1 and SN3 prototypes, SN4 is on track to be the third full-scale, functional Starship prototype built in a handful of weeks thanks to major factory upgrades SpaceX has completed in recent months. While the loss of any particular prototype is undoubtedly a setback each time it happens, such a high rate and (apparently) low cost of production means that no single failure should be a major disruption, allowing SpaceX to iterate incredibly quickly as it learns from a flurry of real-world tests.

On April 11th, SpaceX completed the second of either three or four total stacking milestones for Starship SN4, pushing the ship halfway (or more) towards completion. (NASASpaceflight – bocachicagal)

Like SN3, SpaceX’s next prototype will soon be fully stacked and transported down the road from the factory to a nearby launch and test facility, both situated directly on the South Texas Gulf Coast. Based on SN1 and SN3, SN4 could be just a week or so away from that transport milestone. SN3, for example, reached Starship SN4’s current state of assembly around March 20th. Eight days later, the vehicle was moved to the launch pad for its first tests.

Starship SN4 appears to be no more than a few days away from its final stacking milestone, pictured here with Starship SN3 on March 26th. (Elon Musk)

On April 12th, SpaceX technicians flipped Starship SN4’s aft-most section, doubling as a bottom dome of its liquid oxygen tank and a mounting point for three Raptor engines. Starship SN3 passed the same point around March 18th, just ten days before it was moved to the launch pad. Per SN3’s assembly schedule, it should be just 2-3 days before SpaceX wraps up Starship SN4’s engine section by adding another two rings, followed by the engine section’s integration with the rest of the rocket approximately 5-7 days from now.

Starship SN3’s thrust structure and aft dome was flipped on March 18th. (NASASpaceflight – bocachicagal)
Starship SN4’s own tweaked thrust structure and aft tank dome was flipped on April 12th. (NASASpaceflight – bocachicagal)

Based on Starship SN3’s behavior before a badly-designed test triggered the series of events that destroyed it, the ship appeared to be performing extremely well with its upper (methane) tank almost completely full of super-cool liquid nitrogen. If Starship SN4 does a similarly good job and makes it through the rest of the test that SN3 was unable to, SpaceX has three Raptors already tested and ready to go for their first triple-engine static fire ever.

At this point, those engines are simply waiting in a nearby hangar for a Starship prototype to be declared flight (or at least static fire) worthy. Even more excitingly, should both the engines and the Starship in question perform flawlessly during those tests, the first flights are expected to follow very soon after. Whether it’s able to summit that particular hurdle, Starship SN4’s current rate of production suggests that the ship will be ready to kick off testing later this month, perhaps less than three weeks after its predecessor kicked the bucket. Stay tuned!

SpaceX’s next Starship prototype is already closing in on its first tests
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