Rocket Launches Are Surprisingly Successful

http://blogs.scientificamerican.com/life-unbounded/rocket-launches-are-surprisingly-successful/

by anthelios • 10 years ago

62 27 10 years ago

blogs.scientificamerican.com

wmkn• 10 years ago

What does 'failure' mean in this statistic. Does failure always mean a catastrophic failure (i.e. the recent SpaceX launch) or are failures also rockets not leaving the platform?

I would think that a >5% failure rate is surprisingly high for something we have been doing more than 70 years.

Heliosmaster• 10 years ago

In the last 70 years we've focused a lot on not having failures, spending all the money it took.

Now, the focus is somewhere else (namely reducing the cost per launch, in order to get us a lot more to space).

kiba2• 10 years ago

Pretty sure that SpaceX is focused on reliability. One of the analogy that Elon Musk used is comparing a Honda Civic versus a Ferrari, asking which is more reliable.

Historically, rockets are focused on performance, not cost.

SpaceX's focus on producing cheaper rocket and launching more of them will yield more reliability. You make more of them, you make more mistakes, more opportunities to correct them.

Eventually you'll have a system for making very reliable rockets.

pjscott• 10 years ago

Accepting lower reliability of rockets doesn't buy you as much cost reduction as you might expect. Payloads are usually very expensive, so even a moderately increased risk of losing one can be pricy.

What SpaceX is doing is accepting worse performance in exchange for lower cost. Hopefully that'll make things more reliable in the long run, rather than less, since they won't be pushing the envelope quite as much as competing designs. (Remember the Space Shuttle Main Engines, which had to be practically rebuilt after each flight? That was done in order to get the amazing performance needed to make the Shuttle work at all.)

bunderbunder• 10 years ago

If you follow the handy link to the source that the article provided, you'll get some more information.

Incorrect orbits are counted as failures, and there are some additional tables that break down the failures by type. It does not look like the rocket simply not going up is counted in the statistics - I'm guessing that always represents an abort rather than a true launch attempt.

manarth• 10 years ago

Incorrect orbit of a secondary payload is also included in the failure count (I was thinking of a 2012 Falcon 9 launch, where the primary payload was successful but the secondary payload didn't reach its intended orbit).

oh_sigh• 10 years ago

I've never heard of a rocket not leaving the platform. Every launch I've seen, the rocket left the platform, or destroyed itself on the platform.

I think(but don't have the data on hand) a more common failure scenario is the rocket launching, and the payload getting into space, but not able to attain the desired orbit.

imaginenore• 10 years ago

The recent SpaceX event was not a launch. It was a test a few days before the scheduled launch.

amelius• 10 years ago

I think it is far more surprising that an IC fab can create a chip with millions of transistors, without even a single defective one.

gvb• 10 years ago

The number of components in rockets and IC transistors are probably roughly comparable. ICs have the advantage that they are making a huge number of only a couple of different things (e.g. transistors, resistors, capacitors). Rockets are composed of a huge number of different things, many of which are totally unique, which makes them much more challenging to build successfully.

Their failure rates are similar, but IC die failures are much less public.

Ref: https://www.quora.com/What-is-a-typical-value-for-good-yield...

marcosdumay• 10 years ago

The number of components in rockets and IC transistors are probably roughly comparable.

Unless you are counting the payload, I really doubt it.

ICs are only possible because people create some way to mass manufacture those features, and people don't even design the features by themselves.

If people created them at the traditional route of "manually design|manufacture this -> encapsulate into component -> use components to manually design|manufacture that -> encapsulate again...", it would be impossible to create chips as complex as we have now. But there still aren't better way to produce rockets.

All the problem with rockets is that they are created by joining a big number of things that don't really like to stay together (or, in a few cases, don't like to stay by themselves either). I doubt they have more bare complexity than a modern car.

sevenless• 10 years ago

The way I've heard this explained, fuel is 3% of the mass of a modern car, 45% of the mass of a passenger jet, and 90% of the mass of a rocket. That means the structural engineering margins of safety for a rocket are much smaller, as there's very little mass fraction available to build redundancy into. There just isn't a lot of 'rocket' in a rocket. That, not complexity, is the root cause of why rockets aren't so reliable.

There's an even more basic physical reason why 'rockets are hard'. It's easy to explain in energy units of kT, the approximate energy of a gas molecule at room temperature. A carbon-carbon bond has an energy of 140 kT, while the gravitational potential energy of a carbon atom on Earth is 300 kT. If the Earth's gravitational potential were much closer to kT, room-temperature gas molecules would be able to diffuse out, we would have lost our atmosphere to space, and humans wouldn't exist. But that means that for a chemical system to escape Earth's gravity, needs a clever arrangement whereby most of the energy contained in its chemical bonds goes to a small fraction of its molecules. In a way, it's surprising not that chemical rockets are hard, but that we're lucky enough to be able to use them at all.

tonyarkles• 10 years ago

That's a whole other very interesting industry. You're right, in a way. I too find the effectiveness of the semiconductor industry exceptionally fascinating.

But it should be noted that most IC designs don't have 100% yield, especially at the cutting edge process nodes. Depending on where the defects are, dies are either thrown out or "binned" (e.g. if a high-end CPU has bad transistors in a section of the cache, that section of the cache is disabled and the CPU can carry on its life as a Celeron).

If you really want to melt your brain a little bit with scale, think about RAM. Every bit in a stick of RAM has n transistors (1 <= n <= 4, depending on the design), plus a capacitor. For an 8GB stick of RAM, you're looking at possibly 32 billion transistors and 8 billion transistors! Even just the fact that we squeeze that many of anything into the space we do is incredible! And then for good measure, we change the signals going to it 1-2 billion times/sec!

fixermark• 10 years ago

e.g. if a high-end CPU has bad transistors in a section of the cache, that section of the cache is disabled and the CPU can carry on its life as a Celeron

For me, that's the part that is really fascinating about the fab industry. We have a statistically-reliable method of fabbing, but we build in the necessary fallbacks in the chip design itself that if a chip partially fails quality control, we can scale it back and sell it as lower-end product. It's intriguingly analogous to the quality process in gemstones, except that chips aren't found---they're made via mechanisms that we can't perfectly control.

adrianm• 10 years ago

I thought yield rates were a thing? (Although a closely guarded secret for obvious reasons.)

api2• 10 years ago

... or that a newborn with a defective heart can be "repaired" hours after birth and then live a normal human life span.

We really do live in an incredible age. The hedonic treadmill effect blinds us to this.

JabavuAdams2• 10 years ago

Potential energy. I'm fascinated by ICs as a human artefact, but they don't have to sit on your desk containing tremendous energies and not exploding.

plumcrush• 10 years ago

One have to defy gravity and the other one need not !

fspeech• 10 years ago

Large memory circuits have redundant circuits designed in so that they can be repaired during testing if necessary, otherwise the yield would be a lot lower.

pyrale• 10 years ago

Sounds like a PR article written just in time to rescue spaceX. The way data was picked (only half a year, many one-off new players) makes it look like 5% failure rate across the industry is the norm :

https://en.wikipedia.org/wiki/List_of_Ariane_launches

https://en.wikipedia.org/wiki/List_of_Atlas_launches_%282010...

Some rockets can claim years or decades of service without losing a single satellite.

api2• 10 years ago

Sure. I do have to point out though that those systems are not innovative.

I personally expect SpaceX to have more failures and am not surprised that they have. Back when NASA and the USSR were innovating in the 50s they both blew up a lot of stuff.

JabavuAdams2• 10 years ago

Hairless Ape 1: Ok, we're going to strap you into a tin can on top of huge tanks of stuff that will freeze you, burn you, and maybe give you cancer. Then we'll light it. Okay?

Hairless Ape 2: Sign me up. Sounds Awesome.

I love/hate you hairless apes. Give 'er!

bogomipz• 10 years ago

For anyone interested in seeing an actual rocket launch(in the US), this article is a really good resource:

http://www.space.com/32683-see-a-rocket-launch-in-person.htm...

Animats• 10 years ago

No, they're not. Failures are around 4% - 5%, and they've been around that since the 1980s.

Chemical fuels are just barely powerful enough to allow reaching Earth orbit. They can't get any better; they're already as energy dense as chemistry permits. NASA's "The Tyranny of the Rocket Equation" explains this clearly.[1] The payload fraction for the Saturn V was about 1%. The Space Shuttle, 4%. A 747 freighter, about 25%.

The fuel fraction for rockets is so high that the structures have to be weight reduced too much. If you could build a spacecraft with the weight budget of an airliner, it could potentially be as reliable as an airliner.

With nuclear engines, one could beat those limits. Early plans for Apollo included a nuclear upper stage. But nuclear is messy.

That's why rocketry hasn't progressed much since the late 1960s.

[1] http://www.nasa.gov/mission_pages/station/expeditions/expedi...

_lbaq• 10 years ago

The basic physics may be the same now and in the 60's, but there is allot that can be done better in the rocket building industry.

Lutz Kayser (of OTRAG [1]) once said that rocketry currently is like "transporting potatoes in a Rolls-Royce".

Build inexpensive, modular rockets like OTRAG, that can be clustered (and possible reused) and you may cut at least some cost out of the equation.

[1] https://en.wikipedia.org/wiki/OTRAG

Rocket Launches Are Surprisingly Successful

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