Featured Image Source: NASASpaceflight via YouTube
SpaceX founder Elon Musk envisions a future where humans are a multi-planet species, capable of travelling to Mars and beyond. His rocket company is actively developing technology that will change the course of humanity's future. Engineers at SpaceX are developing Starship to make that ambitious goal a reality. They are currently manufacturing and testing Starship prototypes at their facility located at Boca Chica Beach in Brownsville, Texas. On Friday, teams conducted a pressurization test on the SN1 Starship prototype. After being filled with cryogenic (super-chilled) inert liquid nitrogen, the test vehicle's propellant tank was over pressurized causing Starship SN1 to collapse in an explosive way. SN1 flew to the air enveloped in white vapor clouds, as it fell to the ground and broke apart. Boca Chica residents captured the explosive event on video. Last night, Musk shared the footage (shown below) of Starship SN1's destructive pressurization test, to his 31.6 million followers via Twitter, alongside a caption that read: "So … how was your night?"
"It's fine, we'll just buff it out," Musk joked. "Where's Flextape when you need it!?"
It’s fine, we’ll just buff it out— Elon Musk (@elonmusk) March 2, 2020
Musk has a great sense of humor, I asked him, "So, what did y'all learn from this event?" To which he responded:
"There’s a puck at the base that takes the engine thrust load. Don’t shuck the puck!"
The destructive pressurization test was caused by a "puck" at the bottom of the SN1 vehicle that takes on a lot of the thrust load power. Explosions during the initial phase of developing a new spacecraft are common, that is how engineers figure out what works and what does not.
There’s a puck at the base that takes the engine thrust load. Don’t shuck the puck!— Elon Musk (@elonmusk) March 2, 2020
Musk also shared that SpaceX aims to test the next Starship prototype in line referred to as SN2, in the next few days. Teams have been building many stainless-steel parts since early January. SN2 will be stripped "bare minimum" in order to pressure test the thrust puck welding to the dome structure. First, they will test the dome to inspect the welds with water then conduct another cryogenic pressurization test. Musk explained:
"We’re stripping SN2 to bare minimum to test the thrust puck to dome weld under pressure, first with water, then at cryo. Hopefully, ready to test in a few days."
We’re stripping SN2 to bare minimum to test the thrust puck to dome weld under pressure, first with water, then at cryo. Hopefully, ready to test in a few days.— Elon Musk (@elonmusk) March 2, 2020
The SN2 version will feature improved manufacturing and welding techniques. Teams previously performed cryogenic pressure tests to test the strength on stainless-steel propellant dome tanks. Starship's propellant dome tanks are the hardest part of the craft to build because these need to be light enough to not add on extra weight to the craft but strong enough to hold highly pressurized propellant inside. On January 10 during a tank made it to 7.1 bar during a pressurize-until-collapse test, that day Musk shared some details about the test result, "Dome to barrel weld made it to 7.1 bar, which is pretty good as ~6 bar is needed for orbital flight. With more precise parts & better welding conditions, we should reach ~8.5 bar, which is the 1.4 factor of safety needed for crewed flight." On January 28 SpaceX conducted another test and reached 7.5 bar. A couple of days later, SpaceX conducted a cryogenic test that accomplished 8.5 bar that would be the strength needed for a human-grade spacecraft. That day, the explosive test demonstrated that the fuel tank is strong enough to withstand the pressure it would experience on future human missions to space. The propellant test tank reached an internal pressure of 8.5 bar, or about 8.5 times the pressure of Earth's atmosphere at sea level. So, Starship SN2 will also be used as a test prototype, they will aim to replicate the results. And ensure they can achieve manufacturing a structure that can withstand extreme pressures before building a fully assembled Starship for a test flight.
We’re now building flight design of Starship SN1, but each SN will have at least minor improvements, at least through SN20 or so of Starship V1.0.— Elon Musk (@elonmusk) December 28, 2019
SpaceX aims to build as many as 20 Starship prototypes, SN1 through SN20 in Texas this year. Musk said in December, "We're now building flight design of Starship SN1, but each SN will have at least minor improvements, at least through SN20 or so of Starship V1.0." All will undergo similar testing, until engineers figure out what works best, they will make design changes needed towards improving the craft along the way as they work toward developing a Mars ready Starship. First flight ready vehicle is expected to conduct a 20 kilometer test flight above Boca Chica. The coming months of Starship testing are guaranteed to be exciting! Good luck to SpaceX!