Rocket redundancy is tailored to mission risk, cost and recovery time

Human-rated Falcon development required more backups and failsafes, increasing complexity, cost and mass, according to the supplied discussion. Lower-cost vehicles may instead add redundancy to components considered most likely to fail.

Helios was described as using triple computers and a single engine with dual igniters. In stable orbit, a vehicle may have enough time to reboot after computer failures, unlike during time-critical flight phases.

Critical systems can receive redundancy, but a single engine may remain a mission-ending single point of failure if it fails to start or keep running.