SpaceX tests a Starship dome tank at SpaceX Boca Chica

Featured Image Source: @LabPadre via YouTube

SpaceX is in the process of developing Starship, a stainless-steel spacecraft that will one day enable life on Mars. A production line of Starship prototypes are under assembly at the company’s South Texas facility situated in a small village at Boca Chica Beach, Brownsville, TX. The founder and chief engineer at SpaceX Elon Musk, said in December he expects SpaceX to manufacture up to 20 Starship prototypes this year, each featuring minor changes to test out. These prototypes are referred to by serial number, SN. So far, engineers have tested Starship SN1, SN2, SN3, SN4 – all were destroyed during pre-flight preparation tests. Through, testing engineers figure out what is needed to develop a space-ready spacecraft. Currently, teams are manufacturing Starship SN5 and SN6, which will undergo the same pre-flight preparations. Including structural pressure testing, in which the stainless-steel vehicle is filled up with sub-cooled liquid nitrogen to test if the structure can withstand pressures it would experience during flight. Starship must withstand a pressure in between ~6 and ~8.5 bar strength; A ~6 bar is needed for orbital flight and ~8.5 bar is needed for crewed flights. If a prototype passes the cryogenic pressure test, the next phase is a static firing of a Raptor engine.

That’s the goal. There a few known weak points on this test tank, probably capable of more pressure. The second test tank to follow shortly has addressed the weak points.

— Elon Musk (@elonmusk) June 15, 2020

Today, June 15, SpaceX conducted a cryogenic pressure test on a Starship dome tank prototype referred to as SN7. The tank was filled with super-chilled liquid nitrogen which caused the entire structure to fill with visible frost all around – “…There a few known weak points on this test tank, probably capable of more pressure,” Musk said, “The second test tank to follow shortly has addressed the weak points.” The stainless-steel SN7 dome tank reached strength of around 7.6 bar –“Tank didn’t burst, but leaked at 7.6 bar,” Musk shared, “This is a good result & supports idea of 304L stainless being better than 301. We’re developing our own alloy to take this even further. Leak before burst is highly desirable,” he explained.

Tank didn’t burst, but leaked at 7.6 bar. This is a good result & supports idea of 304L stainless being better than 301. We’re developing our own alloy to take this even further. Leak before burst is highly desirable.

— Elon Musk (@elonmusk) June 15, 2020

Yes

— Elon Musk (@elonmusk) June 15, 2020

Then, the dome tank was intentionally pressured to the max, as seen in the video below, until it bursted. SpaceX will mix their own stainless-steel alloy for future starships to increase the strength factor. The goal is to develop a structure that could withstand a 8.6 bar -which would be the ideal strength to take astronauts to space aboard Starship.

The next prototypes will undergo the same tests. SpaceX runs 24/7 operations in South Texas. Musk sees Starship development as the company’s top priority. "We need to accelerate Starship progress," Musk told his teams. And asked them to "consider spending significant time" at Boca Chica to help the company accelerate Starship development, “For those considering moving, we will always offer a dedicated SpaceX aircraft to shuttle people.” He aims to conduct a 150-meter and a 20-kilometer test-flight above Boca Chica this year and hopes to take a Starship to orbit soon.