A SpaceX Falcon 9 Will Blow Up Very Soon, And That’s OK

They say you can’t make an omelette without breaking a few eggs, and there are few fields where this idiom is better exemplified than rocketry. It’s a forgone conclusion that when you develop a new booster, at least a few test articles are going to be destroyed in the process. In fact, some argue that a program that doesn’t push the hardware to the breaking point is a program that’s not testing aggressively enough.

Which is why, assuming everything goes according to plan, SpaceX will be obliterating one of their Falcon 9 boosters a little after 8:00 AM EST on Saturday morning. The event will be broadcast live via the Internet, and thanks to the roughly 70% propellant load it will be carrying at the moment of its destruction, it should prove to be quite a show.

This might seem like an odd way to spend $62 million, but for SpaceX, it’s worth it to know that the Crew Dragon Launch Abort System (LES) will work under actual flight conditions. The LES has already been successfully tested once, but that was on the ground and from a standstill. It allowed engineers to see how the system would behave should an abort occur while the rocket was still on the pad, but as the loss of the Soyuz MS-10 dramatically demonstrated, astronauts may need to make a timely exit from a rocket that’s already well on the way to space.

In an actual emergency, the crewed spacecraft will very likely be speeding away from a violent explosion and rapidly expanding cloud of shrapnel. The complete destruction of the Falcon 9 that will be carrying the Crew Dragon during Saturday’s test will serve to create the same sort of conditions the spacecraft will need to survive if the LES has any hope of bringing the crew home safely. So even if there was some way to prevent the booster from breaking up during the test, it’s more useful from an engineering standpoint to destroy it.

Of course, that only explains why the Falcon 9 will be destroyed during this test. But exactly how this properly functioning booster will find itself being ripped to pieces high over the Atlantic Ocean in a matter of seconds is an equally interesting question.

A Semi-Simulated Disaster

F9R Dev1 activates its FTS

It was initially assumed that ground controllers would activate the Flight Termination System (FTS) to destroy the rocket and engage the LES. On the Falcon 9 the termination system uses explosive charges to “unzip” the rocket’s propellant tanks and fuselage, rapidly releasing all of the RP-1 and liquid oxygen. This results in a mid-air deflagration rather than an outright explosion.

All things considered, this is the fastest and safest way to neutralize the Falcon 9, and is intended to be used in a situation where the rocket has veered off course and is heading towards a populated area. The FTS has never been used on an operational Falcon 9, but it was used when the onboard computer of the “F9R Dev1” test vehicle determined that it was heading away from the predefined safe zone.

But for the purposes of this test, such an orderly disintegration of the booster doesn’t really fit many potential abort scenarios. The event most likely to trigger the LES during an actual mission would be an engine failure, explosive or otherwise. So for the purposes of Saturday’s test, ground control will simply command Main Engine Cut Off (MECO) at a little over one minute into the flight. The Crew Dragon’s systems will interpret this loss of thrust as a non-recoverable failure, and automatically begin the abort sequence.

Hitting a Brick Wall at Mach 1.5

The time frame for MECO wasn’t selected arbitrarily, either. At approximately one minute into the flight, the vehicle will experience what’s known in the industry as “Max Q”, the point when aerodynamic structural loads will be at their highest. If performing the abort test during the period in which the airframe will be under maximum stress seems like the most difficult time to do it, that’s because it is. Not only is Max Q arguably the point where a structural failure is most likely to occur, but engaging the LES during this stage of the flight will show NASA and SpaceX engineers how the system will perform in the worst case scenario.

What happens next is really anyone’s guess. Once the Crew Dragon fires its SuperDraco engines and pulls away from the Falcon 9 booster, the flat top of the rocket’s upper stage will be exposed to supersonic airflow it was never designed for. It’s very likely the crushing, instantaneous, pressure will cause the booster to collapse. But even if the booster somehow survives the force of the inrushing air, it will have become aerodynamically unstable; it will quickly deviate from the direction of flight and begin tumbling, which will invariably tear the relatively flimsy fuselage to pieces.

In either event, the rapid disintegration of the Falcon 9 and the resulting release of propellants will provide a perfect analog for the sort of dramatic failure that the LES is designed for.

The Final Countdown

If everything goes according to plan, the Crew Dragon will pop its parachutes and splash down in the Atlantic approximately 32 kilometers East of Cape Canaveral. Both SpaceX and NASA recovery teams will use this opportunity to rehearse the delicate task of recovering the spacecraft from the ocean. This procedure has also been practiced previously, but never this far out, or with the Crew Dragon returning from such a high altitude.

A successful in-flight abort test is the final milestone on the long road towards human-rating both the Falcon 9 and the Crew Dragon. If NASA is happy with what they see this weekend, SpaceX will be cleared to bring astronauts to the International Space Station as soon as next month, though finalizing the certification process could push the first operational flight to Spring.

After Boeing’s Starliner failed to reach the International Space Station on its first test flight in December, all eyes are now on SpaceX. Should this test go off without a hitch, the Crew Dragon may well become the first American spacecraft to carry astronauts since the 2011 retirement of the Space Shuttle.

27 thoughts on “A SpaceX Falcon 9 Will Blow Up Very Soon, And That’s OK

  1. Popping off the dragon capsule at max Q makes sense and agree with writer that it would seem representative of a very bad place to have engine failure. But is there any efficacy in a test that causes an explosion just prior to dragon separation?

    1. No. The system is designed to get the capsule away before the booster blows up. If the booster explodes all bets are off. After all the thing you are attached to just blew up. Not really going to end well no matter what.

      1. In the failed Soyuz launch the booster was breaking up prior to the LES activation. The backup LES, because the LES tower had already been jettisoned prior to booster separation. Damage to the upper booster attachment caused it to flip inwards to strike the core stage instead of flipping out and away as it was supposed to, and had in hundreds of launches over the past 50 years.

  2. If they are spending that much money… can they hire a SAM missile to take it down? Could a SAM take it down? Or maybe a use a F-16 or something? Would be much more entertaining!

    1. I imagine a SAM could take it down – it’s basically the same as destroying a ballistic missile in the boost phase. At Max-Q the Falcon 9 speed is “only” Mach 1 and it’s “only” 45,000ft up. Well within the performance limits of modern SAMs – I think.

      1. It may not be quite that simple, remember this target is going straight up, and effectively has no upper limit, so speed is not the only factor. Your SAM would nee to be able not only to follow it, but also catch it, and hit it. All of which present a challenge. This is not an aircraft, but a space craft, so while a SAM may have the range, it may not have the legs to catch it, or the ceiling to keep following it. That 8 1/2 mile head start and similar performance, may make catching up difficult, even if the SAM does have the speed. Assuming it does catch up, by then the rocket and the SAM may well be well past 90,0000 ft, so right onthe edge of space. Check your SAM’s manual and see if it can get there, and get there in time.

  3. I can’t wait to see the video – not many of these are done on purpose.

    Also, Nit-picking man checking in: “This results in a mid-air conflagration rather than an outright explosion.”

    That should be ‘deflagration’, which is the burning-off of explosive materials without creating a supersonic shock wave (you hope…)

  4. Interesting to compare it to one of the tests of the Apollo launch abort system:
    https://youtu.be/AqeJzItldSQ?t=74
    The ‘Little Joe’ rocket that they were testing with broke up in flight, before it had reached the speed and altitude required for the test. However, the escape system detected the breakup and worked perfectly, pulling the (mockup) capsule away from the disintegrating rocket.
    A successful, unsuccessful test.

    1. I don’t know, I’d almost call the Apollo LES test TOO successful — the rocket broke up on its own before the planned breakup, and in addition was well out of expected limits (it was spinning like a rifle bullet which is why it came apart at 1/10th the planned altitude, and tumbled like crazy between LES burnout and parachute deploy, and still landed perfectly and probably wouldn’t have killed the crew) , well past the point where somebody would have already hit the Big Red Button if people were onboard.)

      Also, fun fact: that solid rocket on top of an Apollo CM had about twice the thrust of the entire Mercury-Redstone booster that took Alan Shephard and Gus Grissom above the Karman line. TBH, if I was sitting on top of six million pounds of kerosense and liquid oxygen and it had a major failure, I’d also want the capsule-GTFO system to be enough to get me astronaut wings by itself.

  5. Did Boeing do a similar test when they did theirs on the LES? I suggest this is one of the best tests you can do. Since the Boeing boosters don’t recover, it wouldn’t cost them anything extra to do a destructive test….

    But, y’know, playing favorites at NASA and all.

    Good Luck SpaceX. I look forward to the video.

    1. Oh, but everybody knows Boeing has a lot of experience and a top notch safety culture. LOL

      NASA trying to play favorites might actually kneecap Boeing, because people won’t have the same confidence in their system without the testing. At the time that they pulled the strings to get the shortcuts they had a vastly different public perception of their engineering.

  6. Let me say that I find it odd that SpaceX is going through with a “live test” of the abort system…. and Boeing is going to go through with their first crewed mission after a FAIL on the first test….. (which didn’t even attempt to test the abort system).

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