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SpaceX successfully “ cryopreserved ” the first propellant tank based on the nose of the fully assembled Starship prototype and used the same tank to ignite a Raptor engine, passing one of the last major tests before the 15-kilometer launch of the rocket (~ 9.5 miles) debut.
On November 4th, after some false starts, Starship Serial Number 8 (SN8) kicked off its first round of testing after becoming the first prototype to have a permanently installed nose section. That Wednesday night, SpaceX most likely subjected the rocket to a partial cryogenic proof test that explicitly focused on the SN8’s new nose and a small secondary propellant tank located at its tip. Designed to serve as a secondary reservoir for the relatively small amount of propellant required for the landing of starships, SN8’s two header tanks were likely loaded with cryogenic liquid nitrogen, a safe, non-reactive substitute for liquid oxygen and methane.
Having demonstrated that the Starship SN8’s newly installed liquid oxygen tank and associated plumbing are capable of loading, handling and discharging dozens of tons of cryogenic fluid while sailing on a 40-meter (~ 130 ft. ), SpaceX was ready to move on to the next step: a wet suit test (WDR) and the static fire of Raptor.
Although SpaceX has technically completed eight Raptor static fires on four separate prototypes, including the first three-Raptor static fire ever attempted with the SN8 spacecraft, the company has never attempted a static fire while exclusively drawing propellant from the landing tanks. Anything but essential for starships to be able to reliably reignite their Raptor engines in flight and keep cryogenic landing propellant liquid for hours, days, weeks, and even months, much smaller header tanks make it easier to maintain the highly pressurized propellant is in the right place to refuel the birds of prey.
After several days of back-and-forth test windows and an aborted attempt on November 9, the Starship SN8 finally fired one of its three Raptor engines, fueling the engine with liquid methane and oxygen stored in two separate collector tanks. Oddly enough, a second or two after starting and turning on, the usual Raptor exhaust plume was hit by an explosion of shiny firework-like debris. After a relatively normal five seconds, the Raptor shut down, although the engine seemed to remain partially on for another ten seconds or so, again somewhat unusual.
Ultimately, the observed anomaly could be as simple as debris accidentally left in the vicinity of the Raptor plume or, although less likely, concrete erosion. There’s also the possibility that they were pieces of Raptor’s turbopump or pre-burner complexes, though it’s also unlikely the engine would have continued to run (as it did) if it had lost so much internal hardware.
(Update: Thankfully, NASASpaceflight.com reporter Michael Baylor says the debris cloud observed on November 10 “it’s not a [Raptor performance] concern,” making bearing debris the likely source.)
SpaceX canceled another static fire window on November 11, leaving the next opportunity for a second (out of three) static fire expected between 9:00 and 21:00 CST (UTC-5) Thursday, November 13.
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