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Comment by whalesalad | Hacker News Reader

Well over 100 successful missions carrying a bunch of people and gear up into outer space and then bringing them back home.

I hold it in a good light now, and will likely continue to feel that way. As far as human progress and net good, it was a success.

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100 success and 2 failures. About a 1.6% failure rate from memory.

That’s not a great record. Sure it’s a complex field, and it’s not as dangerous as say being US President, but a failure rate of >1% is not something to write home about.

So what was the failure rate of the previous shuttle?

Its predecessor launch system had 10 successes and 2 failures for the crewed flights. One, they got the crew home safely, but it was close. So that's a 17% failure rate and a 8% rate of failures killing the crew.

Not saying the Shuttle's success rate was awesome; I'm glad we demand more nowadays. But it still represented a pretty decent crew safety improvement for the USA's human spaceflight program.

Notably, both were hardware failures.

Challenger blew up on launch because of a booster failure due to a faulty O-ring seal.

Columbia burned up on re-entry because a piece of insulating foam broke off from the external tank during launch, damaging the heat tiles on its left wing.

One accident per 271,199,439 miles traveled seems pretty damn safe, applying the same standard used for other methods of travel.

https://www3.nasa.gov/centers/kennedy/pdf/566250main_SHUTTLE...

I encourage you to build a more reliable space plane. Please link me to your blog and I will read your updates daily.

100 is frankly not that impressive for software. A 2-9 system will sometimes work 100x in a row, and a 3-9 system usually will.

100 missions. Not 100 code executions.

Sure, but I imagine at least some components only really execute a small number of times per flight, or possibly never in the case of certain error handling code. Stretching the metaphor more than is probably appropriate, I'd treat launching the shuttle and having it come back as a big integration test. A system that passes it's integration test 100 times isn't necessarily particularly impressive in terms of reliability.

We run our integration test tens of times a day, and it fails once or twice a month. Our system is kinda flaky :(

> A system that passes it's integration test 100 times isn't necessarily particularly impressive in terms of reliability.

So extending your own metaphor and using 100 as the number of missions, the integration test failed 2% of the time.

A 2% failure rate isn't impressive, but I'm fine not crediting any of the shuttle issues to software. My only point is that 100 instance of use for purpose isn't enough, to my mind, to argue that a piece of software is exceptionally reliable.

Right, but the shuttle failures were not software failures.

As far as we know, software never caused any dangerous incidents for the shuttle. You can't say that about Arianespace (Ariane 4 #1) or SpaceX (a couple of crashes while trying to land - low stakes though) or Airbus ("just" some bad UX in critical situations) or Boeing (software basically killed a few hundred people).

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