If you have one mission critical system, all your systems are mission critical. It's usually the link you don't expect or don't know about that screws you over

If you have one mission critical system, all your systems are mission critical. It's usually the link you don't expect or don't know about that screws you over. Like an email server, DNS, networking. At any level, a complicated house of cards can easily come down. Thankfully, in rocket engines, simplicity is a design goal.