Here’s why SpaceX really needed to change out that part on Starship

Enlarge / Falcon 9 interstage from the right. Note grid fins. (credit: Lee Hutchinson)

SpaceX's Starship rocket did not launch on Friday morning from South Texas as intended because the company had to replace the actuator on a grid fin. The rocket is now being prepared for a launch during a tight window on Saturday morning, from 7 to 7:20 am local time.

Here's an explanation of why grid fins are so important to the rocket's flight—or, more precisely, its landing.

A little Falcon 9 history

The better part of a decade ago, SpaceX maneuvered an autonomous drone ship into the Atlantic Ocean for the first time with the intent of catching a falling rocket.