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At around 7:15 p.m. local time, SpaceX Starship’s SN8 prototype set one or more Raptor engines on fire for the third time in its history, taking spectators by surprise – only expecting a dress rehearsal. An hour later, CEO Elon Musk revealed that SpaceX had indeed lost control of the rocket.
Unfortunately for SpaceX, this is not the first incident in which a fire led to Starship losing control. In May 2020, the serial number of the Starship 4 (SN4) – the first full-scale prototype to have installed a Raptor – completed its third successful static fire test. Moments later, a ventilation duct adjacent to the engine section caught fire, burning for a minute or two. In the end, possibly due to destroyed wiring or plumbing, SpaceX apparently lost control of SN4 and had to wait two full days for the cryogenic thruster to evaporate and evaporate before crews. can approach the rocket to inspect, repair and regain control.
Now, more likely than not, Starship SN8 suffered a similar – but not identical – failure, cutting off some level of control. Elon Musk took to Twitter about an hour after the Raptor rocket’s third static fire, revealing SpaceX had lost control of Starship’s pneumatics, referring to the hydraulic systems needed to operate most of the rocket’s valves. . For SN8, that meant nothing but bad news.
As cryogenic liquids (and all things in general) heat up, they expand, taking on more volume. To counter this never-ending process of heating, boiling and transforming the cryogenic propellant, the cool propellant is almost continuously charged while the hotter gas is vented, thus maintaining safe tank pressures. If the ability to vent these gases is lost, so does the ability to maintain safe pressures.
As Musk noted above, Starship SN8 fortunately – and unexpectedly – installed one or more bursting discs, referencing single-use mechanical valves designed to open (i.e. burst) above a specific pressure. SN8’s nose rupture disc did just that, bursting to create an outlet for the pressure building inside the rocket and thus preventing the small nose-based liquid oxygen (LOx) tank from exploding. .
Unfortunately, the forerunner of Starship’s loss of control is a much less positive story. According to Musk, one of the flaming Raptor SN8 engines may have suffered a major failure, melting one or more critical engine components. It’s unclear exactly how a seemingly contained engine failure evolved into a complete loss of the Starship’s hydraulics, but it’s safe to say redundancy will be added and updated designs implemented to ensure that ‘a similar failure will not happen again.
Notably, unofficial live broadcasts from LabPadre and NASASpaceflight.com clearly showed Starship literally. dripping molten metal for more than two minutes after the static fire. Whatever the cause of this extremely hot fire, anything that can melt metal continuously for minutes will almost certainly have ravaged the rear of the Starship SN8 and the Raptor engines installed inside. It is nothing short of miraculous that SN8’s LOx main tank was also not breached.
Ultimately, SN8 will likely need extensive repairs – and one, two, or even three replacement motors – before it can safely restart testing and make its 15km launch debut (~ 9, 5 mi). Additionally, SpaceX’s lack of valve control likely means the company will have to wait at least 24 hours before workers can safely return to the launch pad and begin these inspections and repairs.
Update: The roadblock was removed around 11 p.m. local time, and SpaceX workers appear to have already returned to the platform, meaning Starship SN8 has been fully removed from storage and can approach safely. Inspections and repairs will likely begin as soon as possible.
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