SpaceX’s first high-altitude Starship prototype just “passed cryo proof” testing

Elon Musk says that SpaceX's first high-altitude Starship prototype has passed its first major test. (NASASpaceflight - bocachicagal)

SpaceX CEO Elon Musk says that the first high-altitude Starship prototype – known as SN8 – just “passed cryo proof” testing in South Texas, potentially setting the ship up for a ~15 km (9.5 mile) flight test in the near future.

Meanwhile, NASA astronaut Bob Hines recently overflew SpaceX’s Boca Chica, Texas Starship factory with several compatriots, offering an excellent aerial view of the company’s bustling facilities in the midst of Starship SN8’s critical cryo proof test campaign.

Hines managed to catch the Moon alongside one of the T-38 trainer jets NASA astronauts routinely use for training and travel, serving as a reminder that SpaceX won $135 million to build a Lunar Starship that might someday return humans to Earth’s lone companion. Likely with or without NASA’s involvement, the Starship prototype production and test program SpaceX is deep in the midst of will directly determine if and when the company visits – and lands on – the Moon and Mars.

A spectacular aerial view of SpaceX’s Boca Chica, Texas Starship factory, captured by one of the NASA astronauts that might one day ride Starship to the Moon. (Bob Hines – NASA)

Over the last three days, SpaceX has gradually put Starship SN8 – the first prototype meant for high-altitude flight testing – through its paces, beginning with a seemingly aborted “cryo proof” test on October 5/6. During the first attempt, SpaceX appeared to pressurize the rocket tank section with cold nitrogen gas and perhaps a small volume of liquid nitrogen before reopening the highway. Starship SN8 also actuated its large aft flaps under its own power for the first time on October 4th and SpaceX has performed several more actuation tests in the days since.

24 hours later, SpaceX tried again, this time successfully loading Starship SN8’s liquid oxygen and methane propellant tanks with perhaps a thousand metric tons (2.2 million pounds) of liquid nitrogen – used to simulate the ultra-cold temperatures of cryogenic propellant without the risk of a catastrophic fire or explosion. After cryo load, SpaceX reportedly attempted to pressurize the rocket’s tanks to their limits but the test was stopped somewhat short when Starship SN8 sprung “a small leak…near the engine mounts” after reaching pressures of 7 bar (~100 psi).

Precisely as Musk predicted, SpaceX apparently managed to fix the minor leak in less than 24 hours and began the third round of Starship SN8 cryo proof testing late on October 7th. Once again, the rocket was fully loaded with liquid nitrogen and spent some 2-3 hours under cryogenic stress as SpaceX likely stress the thrust structure (“thrust puck”) by simulating the thrust of Raptor engines with hydraulic rams. Nothing out of the ordinary happened and Musk has yet to comment on the test, suggesting that things went largely as planned.

Intriguingly, SpaceX then geared up for a fourth night of cryogenic testing on October 8/9. It’s not entirely surprising that the company would want to test the first Starship built primarily with a new steel alloy as thoroughly as possible. If SN8’s fourth night of testing produces satisfactory results and SpaceX is less than concerned with the leak discovered during the second round of testing, the company could be ready to install three engines and attempt the first multi-Raptor static fire test ever.

Update: SpaceX CEO Elon Musk says that Starship SN8 “passed cryo proof” testing, most likely setting the rocket up for the first triple-Raptor static fire test ever attempted. If SN8 passes static fire testing, it will most likely be outfitted with a nosecone and forward flaps and attempt another three-engine static fire using smaller ‘header’ propellant tanks, ultimately preparing it to support the first high-altitude flight test of a Starship prototype if all goes according to plan.

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SpaceX’s first high-altitude Starship prototype just “passed cryo proof” testing
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