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Elon Musk Asks Twitter For Help In Finding Cause of SpaceX Explosion (gizmodo.com)
On September 1, SpaceX's Falcon 9 rocket exploded on the launch pad at Cape Canaveral, Florida, and destroyed the AMOS-6 satellite that belonged to Facebook, which was going to be used to beam internet to developing parts of the world. Since the cause for the explosion has yet to be solved, SpaceX CEO Elon Musk is asking for help via Twitter. Slashdot reader Thelasko writes: Elon Musk stated on Twitter last night, "Still working on the Falcon fireball investigation. Turning out to be the most difficult and complex failure we have ever had in 14 years." He went on to say, "Important to note that this happened during a routine filling operation. Engines were not on and there was no apparent heat source." Other Tweets mention a "bang" sound before the fire, and that SpaceX "have not ruled out" the possibility that something struck the rocket.
Samsung note 7 ?
At least one possible explanation.
Again, AMOS-6 was not in any way owned by Facebook. They had simply signed a contract to lease a significant portion of the Ka-Band payload pointed at sub-saharan Africa. But don't let facts get in the way of your hate.
...si hoc legere nimium eruditionis habes...
The first one who claims that the other person "hates" wins!
Did they have the autopilot turned on?
I stole this Sig
It did not belong to Facebook, but to Spacecom. It was not manufactured by Facebook, but by IAI.
Proof:
https://www.youtube.com/watch?...
+0 Meh
Someone misread it as a ka-bang payload.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
My money would be on a .50 cal Anti Material Rifle. It was an Israeli satellite. A quarter-billion dollars would be a juicy target for the Palestinians.
The fire originated around the upper stage oxidizer tank, which would be the logical choice of target to shoot at. Leaking fuel isn't necessarily dangerous. Leaking oxidizer will make everything in the area kindling for the tiniest of sparks.
Opening it up to Twitter is a great idea. It allows all the arm chair scientists to express all their ideas based on nearly no facts to feel like they are useful. While people are doing the real work can just ignore the feed and not get indicated with calls and emails expressing their awesome theory.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Seems like one of the upgrades they should have for launch and prep is high-speed cameras pointed at the thing.
The first flash of light looked a lot more like an electrical discharge than it did any sort of combustion.
Hard to tell with what was published on Youtube though.
Extreme high speed cameras can usually only operate for brief periods due to buffers and heat and regular CCTV is probably too slow to get useful data. If it was shot by a bullet the act of penetrating the tank probably produces enough sparks to cause an instant explosion.
Live today, because you never know what tomorrow brings
It would have been nice if the summary had mentioned what specifically he asked for, rather than including everything but what he asked for. They make it sound like he asked Twitter to solve the problem. What he actually asked twitter for was any photos or videos of the event that anyone may have:
The connection with the "bang" is precisely what he wrote immediately after the first tweet:
If they have more videos, they can triangulate the location of the sound and determine whether it came from the rocket or elsewhere.
Musk did Not just go on Twitter and say "Well, we're baffled - go on, Twitter, figure out why it exploded for us!" like the summary makes it sound.
"I need swat, tactical, the guys with the flashlights on their guns, those guys with the big shield thingies"
It's trickier than that. They were loading LOX. There was no RP1 in the upper stage yet. So why did the LOX explode?
I've read a fair bit on LOX handling, and while it's tamer than, say, HTP, there are some risks in handling it. The biggest one is contamination - which has taken down craft in the past. Most notably, the X-1A and X-1D were taken down by a contamination from a chemical used in the manufacture of their gaskets. Most organics are incompatible with LOX and become contact sensitive, including - wait for it - tending to be set off by pressure changes.
Another issue is the tank itself. LOX is compatible with most aluminum alloys, hence aluminum is frequently used for LOX tankage. However, there are some caveats. One, it must be well cleaned in a proscribed manner, due to the aforementioned contamination issues. Furthermore, it must have an intact oxide layer. If the oxide layer is damaged (bending, stretching, shearing, overaggressive cleaning) or never formed, it must be exposed to atmospheric air and allowed to reform; it begins reforming immediately but takes about three days to reach maximum thickness (slowing with time). Bare aluminum is still not hypergolic, but it is impact sensitive with LOX. It can also be set off by the same phenomenon that damages the tank - for example, heavy warping, which can create localized hot spots.
Contamination is generally considered more of a concern, however (particularly since SpaceX uses aluminum-lithium, which is more resistant to impact/pressure-induced explosion with LOX than non-lithium alloys). That said, regardless of what causes the initial burn, if temperatures are high enough, the aluminum will burn, and it burns very aggressively. Indeed, it was the addition of aluminum powder that revolutionized solid rocket propellants (powdered to make it easier to ignite and burn completely, as well as to blend), giving them a major simultaneous improvement in ISP, thrust, propellant density, and burn quality. Aluminum has such a high affinity for oxygen that it also burns in CO2 and water, stripping the oxygen from them. The general way firefighters put out large aluminum fires is.... they don't.
All of that said, these sort of problems are rare. Which makes one wonder about the unusual factor in SpaceX's case: densified/superchilled propellants. SpaceX is the only major launcher to use them, and the behavior of superchilled LOX isn't anywhere near as well studied as that of LOX at its boiling point. It changes what may liquify or freeze in contact with it, it changes the flexibility or fracture properties of physical components on contact with it, it has a higher viscosity, etc. Things that freeze into it could melt/boil as the LOX warms up as well. So it obviously draws the question, is this problem a result of the use of superchilled LOX, some unanticipated effect in the production / storage / delivery system that led to problems within the tank, or an unexpected reaction within the tank itself?
"I need swat, tactical, the guys with the flashlights on their guns, those guys with the big shield thingies"
You're a hater!
Yes. Like every other new complex technology it takes time to find all the problems and fix them. Early cars had a tendancy to catch fire and break down. Steam engines would explode. Airplanes would crash. Will rockets ever be as safe as airplanes probably not on a per launch bases but on a miles traveled perdeath they will be safer than cars are today.
It's trickier than that. They were loading LOX. There was no RP1 in the upper stage yet. So why did the LOX explode?
Do you have a source for that? Typically the RP-1 is loaded first as even though it's chilled, it's far more thermally stable than the super-chilled LOX. The LOX is loaded into the tanks just before launch so that it doesn't have time to warm up before the rocket is ignited.
From the US Launch Report video, it's also pretty clear that the RP-1 was already in both stages when the anomaly occurred. In a deflagration like that, it burns with big movie-style orange flames, and that's exactly what we saw from both the upper stage, and the lower stage as the rocket came apart.
...si hoc legere nimium eruditionis habes...
It must have been the new FaceBook 'news' algorithm that caught fire because it has too many wacky conspiracy theories.
Nah. Twitter will be too busy censoring possible theories claiming they're harassing the explosion.
Om, nomnomnom...
If you look at the published video on YouTube of the explosion and go frame by frame, there are two events. The first is a bright flash that lasts a few frames and appears much larger than it actually is because it is both saturating the camera and illuminating the condensation clouds. You can see the illumination effect clearly in the first frame the flash appears as there are distinct shadows in the clouds. It's unclear to me whether this triggering event is electrical or chemical in nature, but I'm not an expert. Three observations can be made, however: (1) it is bright enough to cause lens flare in the camera which allows pinpointing its source despite the saturation (look for the X, carefully find its center -- you can do that very accurately -- and then back up a handful of frames; see that triangle thingy with a thin tail? That's what failed.) Then, (2) the initial flash is small and is followed almost immediately by a medium sized flash, and in turn that releases the fireball. Then, (3) the condensation clouds aren't moved by the explosion for about 12 frames until the fireball really starts to form, suggesting that the earlier flashes marked the release of lots of energy that may have been primarily radiation (light) rather than heat because they didn't expand the air enough for me to think of them as explosions. The video is 60 FPS, and the initial flash forms within one frame, so that's only 17 ms. The consdensation clouds don't start moving for 200 ms from the main explosion.
So we have one event that's exceedingly hot that triggers a second that's also exceedingly hot, that releases enough LOX to start the fireball. I'm thinking static discharge from the LOX filling.
One thing I don't understand, though, is that if you watch the fireball in slow motion, as the lower front heads toward the ground, there are seemingly waves passing through it. What are those? Additional shock fronts from tertiary explosions?
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
Because if you look closely, the object is not close to the rocket when it first starts to explode so it's probably a bird a mile closer to the camera.
That's quite a strawman. Nobody thinks government "can't do anything right." The government has obviously done many things right. But can free enterprise do some things better? And better yet, can they do those things on their own dime? We'll see.
We don't have a state-run media we have a media-run state.
Nope, it's a disinformative post.
The RP-1 was already loaded. RP-1 can happily sit there forever at ambient temperature (it's just high-grade kerosene), it won't boil off like liquid oxygen. The LOX is loaded last because of that boil-off concern.
The firefall of burning kerosene is plainly visible in the video. OP is an idiot.
-- Alastair
I think GP is one of those who think that the government is the only one that can do things right. If so, he might want to read the Rogers Commission Report.
Extreme high speed cameras can usually only operate for brief periods due to buffers and heat and regular CCTV is probably too slow to get useful data. If it was shot by a bullet the act of penetrating the tank probably produces enough sparks to cause an instant explosion.
You don't need extreme highspeed cameras though. I have a camera that you could put together a sufficient package for under $20k that shoots 300fps at 1080p for a full hour. 300fps would give you 3ms.
I'm sure that Spacex right now would LOVE to have 3ms video precision from 3 angles. In fact I know SpaceX owns these cameras. They were probably all rigged up though on the drone ship and nobody started them for just a static fire.
Inside LOX tank their are anti slosh baffles made out aluminum which are welded to the inside of the tank. During fueling those welds will be under thermal stress, if one of the welds gave out it would expose Al metal to the LOX then BOOM. The tank material itself reacted with the Pure O2.
It's the nature of the beast when dealing with LOX tanks. 1st)It would be wise to let the tank sit with a pressurized with a couple of psi of O2 for several weeks building up a thicker ceramic AlO2 layer. 2nd) implement a staged cool down procedure before filling tank with cryonic oxygen to reduce stress on welds..
This paper has a pretty thorough analysis of igniting cryogenic fuels by the force of cavitation, that is, collapsing of bubbles that could, for example, form from the interaction of super-chilled LOx and LOx condensed from the atmosphere.
You don't need a bullet, or a ray gun, or even a rock to ignite cryo fuels under the right circumstances.
The shockwave from the failure of a pipe or weld could be enough to ignite the fuel.
Mission: To provide products that consume time and energy as entertainingly as permitted by the laws of thermodynamics.
More dis-information. The kerosene for the Full Thrust version is chilled to -7 degrees centigrade , boosting its density by 2.5 - 4.0 percent.