Around 7:30 pm local time, the SpaceX Starship prototype SN8 fired one or more Raptor engines for the third time, capturing spectators – just in anticipation of a dress rehearsal – in amazement. An hour later, CEO Elon Musk announced that SpaceX had effectively lost control of the rocket.
Unfortunately for SpaceX, this is not the first time the starship has lost control due to a fire. In May 2020, Starship Serial No. 4 (SN4) – the first full-scale prototype to install the Raptor – completed its third successful static fire test. A few moments later, a vent line next to the engine section caught fire, burning for a minute or two. Eventually, possibly due to destroyed wiring or plumbing, SpaceX will be able to use S.N. 4 lost control and had to wait a full two days for the rocket to boil and evaporate before teams could contact, inspect and regain control.
Now, not likely, Starship SN8 has had the same – but not the same – failure by cutting off some level of control. The third raptor of the Elon Musk rocket went on Twitter about an hour after the stationary fire, in which SpaceX lost control of the starship’s pneumatics, and mentioned the hydraulic systems needed to operate most of the rocket’s valves. For SN8, that means nothing but bad news.
As the cryogenic fluid (and in general all things) expands, more volume is taken up. To resist the final process of cryogenic propellant warming, boiling and turning to gas, fresh propellant is loaded almost continuously while the hot gas is ventilated, thus maintaining a safe tank pressure. If the ability to vent those gases is lost, the ability to maintain safe pressure goes with it.
As Musk noted above, Starship SN8 is attributed – and unexpectedly – to one or more burst discs installed, referring to a single-use mechanical valve designed to open above a certain pressure (i.e. burst). S.N. The 8’s Nakcon burst disc did the same, exploding inside the rocket to create an outlet for the pressure building and thus preventing the small nose-based liquid oxygen (LOX) tank from exploding.
Unfortunately, the forerunner of losing control of the starship is a much less positive story. According to Musk, one of the Raptor engines was a S.N. 8 The flammable can cause a significant failure, dissolving one or more complex engine components. It is not clear how the engine failure evolved into the total loss of Starship Hydraulics, but it is safe to say that redundancy will be added and an updated design will be applied to ensure that such failures do not recur.
Notably, both unofficial LabPadre and NASSSPSflight.com livestreams showed Starship quite literally. Dripping molten metal For more than two minutes after a steady fire. Whatever the cause of the extremely hot fire, anything that could melt the metal for minutes on end would almost certainly destroy the spacecraft behind the starship SN8 and the Raptor engines installed in it. Not surprisingly, the SN8’s main LOX tank didn’t break either.
Eventually, the SN8 will probably need extensive extensive repairs – and one, two, or even three replacement engines – before it can safely resume testing and move on to its 15 km (~ 9.5 mile) launch. Additionally, SpaceX’s lack of valve control means workers will safely return to the launch pad and the company will have to wait at least 24+ hours before it can begin inspections and repairs.
Update: The roadblock was removed around 11pm local time and SpaceX workers appear to have already returned to the pads, indicating that Starship S.N. 8 is completely closed and is safe to come in contact with. Inspections and repairs will begin as soon as possible.
