It’s been more than 40 years since the first successful space shuttle launch. However, as we saw with the recent NASA launch, we still have launch failures. Why is it so tough to achieve reliability in space shuttle launches? Does this apply to all space technology?
In:
There are many many little parts to a space shuttle launch. Humans make mistakes and forget things. Most mistakes result in complete failure.
To add to that risk, humans are pushing the boundaries of modern materials. As technology improves and humans develop better metals, hybrid metals, and plastics, successful space launches become more common.
It was once considered crazy to reuse many components of the rockets. This is because the materials could barely handle one launch let alone ten. Now that we have better parts, multi-use rockets are becoming more common.
Reliability comes by testing many vehicles. Rockets are expensive; therefore we don’t make a lot of rockets. Given the limited number of tests it takes a lot of time to get enough tests to reach high reliability.
BTW. the SLS test shut down because they were to conservative with some hydraulic limits.
Rockets are basicly controlled explosions if we lose control of that explosion then it explodes.
You are taking the components that make a bomb to fling a bunch of extremely complex electronics and machinery plus possibly people off the planet in a way that doesn’t explode in the wrong way often made by the lowest bidder.
These parts are often custom made parts that are not mass produced so not only do they have to be designed specifically for what they are making but they are also made out of exotic materials to be as lightweight, rigid/flexible, strong or thermal resistant so they cost a lot.
Even a single error in math or programing error can literally cause the project to fail cost millions or even billions of dollars and people could die. Also you have to recruit and manage some of the smartest and most educated people in the world and keep them happy and productive doing a stressful job where if they mess up it could have psychological consequences.
* The $260 million Nasa’s Genisis Probe crashed because a pair of parts was installed backwards.
* The $125 million Mars Climate Orbiter was lost because some engineers used feet and other used meters.
* The $370-500 million Ariane 5 Rocket: self destructed because an old piece of software unexpectedly threw an unexpectedly large number.
* The $5.5 billion Challenger Space Shuttle exploded because of an O-ring failed because it couldn’t handle the cold launch weather and no one important listened to the guy that pointed out the problem and even though he did everything he felt he could he quit out of guilt.
No one has specifically mentioned extreme temperatures and/or corrosive fuels as another problem on top of trying to keep the weight to a minimum. Liquid oxygen is about -340 degrees F or -207 C, and this causes 2 types of problems: making materials brittle, and thermal contraction/expansion. For the first, materials that we think of as strong become weak at very cold temperatures – there are plenty of examples of freezing things with liquid nitrogen (-320 F, -160 C) and then shattering them. Putting that liquid oxygen (LOX) into the tanks cools them down, which causes the metal to contract – if the launch has to be postponed, they pump it out, and the tank / surrounding parts warm up and expand. Do this enough times and the connections will weaken and screws may loosen. I’m sure they design for such, but such extremes will eventually find any weak points, material defect, bad weld, etc. We have the most demanding energy/strength requirements for a mechanism that we need to build as lightly as possible.
As with everything it is all about money. The cheapest launches will be stripped down and have as little spare parts and extra strength as possible. There is no point making a rocket out of concrete so it could withstand a crash, but at the same point it has to handle the power of the engines, wind, rain, pressure etc. There is a fine balance, and the closer you are to the limit the less fuel you need or the more weight you have left to use up on the satellite or passengers.
All these people who are saying space travel is hard are totally missing the point. With modern NASA every achievement is in spite of the government. The money and contracts that NASA gets their parts from are managed by Congress. That is to say manged by utter morons. The Space Shitte program was an utteyr failure because of them, and the only reason anyone thinks it good is because of nostalgia and really good media optics. Similarly the SLS program (which I presume you are talking about) is also a flying heap of garbage. We have the technological capability to make the space shuttle look like a child’s toy and it is only the morons in Congress and their greedy defense contractor bosses that are in our way
Because we don’t have that many people invested in building rockets unlike cars and planes and even then, cars and planes fail constantly still.
Reliability is just tough in general if you don’t have many people working together on the project. And even then, like cars, things still always go wrong.
Achieving reliability for NASA is like asking Ferrari to make sure their f1 car won’t constantly break down.
One big consideration is weight vs fuel. If 90% of a rocket is fuel, just to get to near earth orbit, every pound of structure needs 9 pounds of fuel. So the fuel tank needs to be bigger, etc etc etc. Going to Geostationary orbit? More fuel, so more weight. Moon? Mars? Things get heavy really fast.
You can build a bridge to 150% of strength as a back up for worst case situations and aging, and the bridge won’t be that much bigger. It will be heavier, and a rocket fuel/energy budget can’t afford that. That means everything needs to be built – just strong enough – to do the job, and maybe just a little bit more, but no more.
At that point, then you’re into the weeds of vibration, wind shear, rain, turbulence, and other factors that could go past that little bit more. That’s the engineering challenge.
I feel like most professions are like this. Routine surgeries can go wrong. Hard drive manufacturing still produces defective drives. Database conversion always have some unforeseen error after the fact. Bone grafts by my dentist don’t always work. Etc etc etc…
Latest Answers