[mlyle]

The procedures and how software systems handle changes to launch time are members of the set of hundreds of thousands of choices made during design and implementation that need to be validated. Yes, they feel like a "silly mistake" but ultimately most things that lead to failure will be in that category.

[ethbro]

Or, in other words, getting to space is hard because it requires millions of opportunities for silly mistakes.

Most complex engineering projects are hard not because of one thing, but because of the mind-bogglingly large number of things that must all be done correctly.

(1 - x) ^ y, where x is the chance of each small mistake and y is the total number of opportunities, doesn't need a very large x, if y is large enough, for things to start looking dicey.

[camkego]

Yeah, this is a key insight, and something I didn't learn as a software developer with many years of experience until I studied probability formally. Maybe these days this is better known. This is also known as the inclusion-exclusion principal and can be used to model failure probability.

[ethbro]

Thanks for the term! That's combinatorics, so I probably should have remembered it. :/

There are a lot of things I'd love to know the accepted name for, as I came into understanding through the backdoor. I regret that my college CS track didn't include more borrow-courses from physical engineering on reliability (and control theory). So many valuable, applicable lessons.