I know its literally rocket science and a lot of very complex systems need to work together, but shouldnt we be able to iterate on a working formular?
In: Engineering
Look at a rocket. A little less than half* of what makes up its total size is stuff that is designed specifically to explode (the fuel). Most of the other half is stuff that is designed to make that first half explode (the oxidizer). To simplify the process, those two halves are often designed to be hypergolic, which means that they blow up just by coming in contact with each other–no detonater required.
So we should really keep these two chemicals as far apart as possible so they don’t explode. But… We actually need to mix them up and go boom for this thing to work. So don’t mix them up wrong, or you’ll get too much boom. Or you’ll get too little boom and the rocket just falls out of the sky. Don’t get any leaks while your skyscraper-sized pile of explosives is being launched past the stratosphere, or you’ll get boom in the wrong place, which will rapidly turn into boom all over.
And that’s not even counting the crazy handling characteristics. Look at the Space Shuttle main engine. On the inside of the rocket bell, you have a 6000 degree Fahrenheit fire that can literally *boil iron*, and they cool it by running *liquid goddang hydrogen* at – 425 degrees Fahrenheit through pipes around the outside of the bell, which is only about 2 inches thick. That is the last place I would want to put liquid Hydrogen.
So your question should really be: “Why don’t rockets blow up *all the time*?” But you already answered that. Because rocket science.
(* if anyone starts nitpicking about the stoichiometric ratios, I will mock you. This is ELI5, not ELIrocketscientist)
Even rocket science is not always rocket science. It’s dull tedious stuff like FMEA, Failure Mode Effects Analysis, tightening all bolts to spec., dotting i’s and crossing t’s, etc.
It’s not rocket science; it’s rocket engineering and engineering has always advanced through failures.
Three things.
First rockets have a few things that make them prone to going wrong. They need to be as light as possible, while performing to extremely high levels with extreme vibration. Sometimes, they cut too fine of margin, to prevent taking up extra weight that does nothing.
Second, every rocket design is different, which causes different unexpected issues. For example, SpaceX is making much more use of reigniting engines mid-flight, which other spacecraft don’t typically do due to the problems SpaceX is working through.
lastly, when something goes wrong, they have a system that explodes the rocket. They want the big explosion to happen as far away from people as possible. And a bunch of small light pieces falling will cause less potential damage than a large rocket. So they make the big boom happen as soon as they know something is catastrophically wrong.
We aren’t building the same rockets from ages ago. New engineers, designs, and technologies mean many new ways to fail. And we can only predict, calculate, and plan so much for things we don’t know about because we’ve never seen them happen before. This includes novel ways for humans to commit errors.
To add to what everyone else here is saying, rockets by nature work with EXTREMELY volatile fuel, ridiculously high speeds, and friction. All VERY destructive things. So when failures do happen, they happen explosively. When you don’t change the oil in your car and it fails you kind of just pull off the highway. Rockets traveling 17,000 mph that are full of liquid hydrogen don’t just pull off to the side of the road.
For the same reason we don’t have a cure for cancer: just because you understand the big topic doesn’t mean you know everything there is to know about that topic. Cancer isn’t one disease, it’s hundreds that we lump together because they all short-circuit a tissue or cell type and eventually kill you. Being able to “cure” one kind of cancer might give hints about others, but it doesn’t cure them too. Similarly, making one rocket work doesn’t mean every rocket will magically work, especially ones that basically have nothing in common with it.
We’re rethinking what worked before and saying why not? Why can’t we reuse the booster? Why can’t the booster land itself? Why can’t we have Space Tourism? Why can’t we have private enterprise lift satellites? All kinds of “Why can’t we”, which results in more oop’s.
These are test rockets. Aerospace has a long history of vehicles crashing and exploding. Just because its a rocket doesn’t mean its made the same as other rockets. For example, some are 3d printed rockets, and others are adding more engines. There are so many variables that can go wrong at any point. That is why the ones that explode doesn’t have humans on them.
Well, besides the fact most rockets are designed to self-destruct if they lose control or go too far off course, truth is, rockets are complicated. It’s easy to build a rocket design that does the same thing over and over again. Hell, SpaceX has managed to even make boosters reusable. However, if something goes wrong, they tend to go wrong explosively, as the only difference between a rocket engine and a bomb of several kilotons is the rate at which the detonation happens, because a rocket engine is basically a controlled explosion. I mean, in a sense, so is an internal combustion engine, but the difference here is that a rocket, since they are generally headed to space, as to bring an ignitable mixture of fuel. A car can afford to just suck air in from the enviornment, a rocket can’t.
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