Update, 6 p.m.: SpaceX confirmed in a statement this afternoon that the failed engine did not explode, but rather lost pressure and immediately shut down. "Our review indicates that the fairing that protects the engine from aerodynamic loads ruptured due to the engine pressure release, and that none of Falcon 9?s other eight engines were impacted by this event," the company said. We'll have more information about the mission soon.
The "picture perfect" launch of Space Exploration Technologies? (SpaceX) Falcon 9 rocket to the International Space Station on Sunday was not so perfect after all. After a minute and a half of flight, one of the nine Merlin engines exploded failed. The launch was still a success, and the Dragon capsule, containing supplies for the space station, is on its way to dock. But the incident will become more fodder for the debate over the choice to hand over spaceflight design and operation to private companies instead of NASA. Legacy contractors like Arianespace and United Launch Alliance will have ammunition to aim at the fledgling company.
The Good
The best news for SpaceX and its supporters is that the Falcon 9 is designed to suffer the loss of one or more engines during a launch. Last Thursday, during a discussion at Popular Mechanics? Breakthrough Awards, SpaceX founder Elon Musk said that the launch vehicle was "double-fault tolerant." When an engine (or two) fails, the rocket recalculates a new flight path to reach the desired orbit. Last night, when the Falcon 9 lost an engine, the surviving eight engines burned a little longer than expected to compensate, as confirmed by keen-eyed watchers and SpaceX itself.
SpaceX president Gwynne Shotwell released a statement confirming that the rocket did what it was supposed to do. "Like Saturn V, which experienced engine loss on two flights, the Falcon 9 is designed to handle an engine flameout and still complete its mission," she says. "I believe F9 is the only rocket flying today that, like a modern airliner, is capable of completing a flight successfully even after losing an engine. There was no effect on Dragon or the Space Station resupply mission."
The Bad
Just because the rocket survived does not make this event a positive one. With Congress, NASA, and potential satellite-launch customers scrutinizing SpaceX?s every move, any misstep is cause for alarm. Musk himself acknowledged that engine failures are serious things. "I?ve seen where an engine blew up and there is nothing left," Musk said. "It doesn?t bother me too much if it?s on the test stand. It bothers me if it?s on the rocket on a flight vehicle." So expect some long days and late nights at SpaceX as its engineers hunt for the source of the problem.
If SpaceX is lucky, it has already addressed engine reliability and has a solution on the table. In a recent interview at SpaceX headquarters in California, Musk told PM that the main valves in the engines are "heavy, expensive, bulky, and a source of potential failure." He described the system as "two separate pipe-complex valves, each of which has a helium actuator and has to operate simultaneously because if one leads the other too much you would have a hard start . . . otherwise known as your engine just blew up."
Musk says the fix would be to make a single piece that performs the function of two valves. "The injector itself is like a bipropellent main valve, so the injector head sinks back into the injector face. When we start the engine, we basically open a small helium valve that pops the main injector face out and opens up the injector hulls for both the fuel and oxygen simultaneously."
If this was the source of the failure, then SpaceX can reassure its customers that a solution is in the works. If not . . . well, it?s something that needs to be addressed. And that can lead to the kind of cost increase and timeline delay that plagued space-launch companies that preceded SpaceX.
The Ugly
A rocket?s track record is as important as its price tag. Reliability is key, and some of SpaceX?s competitors have many years and successful flights under their belts. The Ariane 5, Delta IV, and Atlas V are about $100 million more expensive than the Falcon 9 but very reliable. Having any kind of anomaly at SpaceX?s early stages casts doubt on the rocket?s reliability.
That is tough on the commercial side of the launch business. But for government launches, the aftershock could be worse. There are few engineers in Congress. When foes of SpaceX and proponents of government-built launch vehicles can say, "the engine blew up," there will be no talk of "fault tolerance" and "redundant systems." They can paint the picture of a space company whose cheap rockets suffer system failures.
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