WHY DIDN'T PALPATINE KILL DARTH VADER AFTER MUSTAFAR'S INJURIES?

In Star Wars Revenge of the Sith, after Darth Vader's fight with Obi-Wan Kenobi on Mustafar, leading to his many crippling injuries...Why didn't Palpatine kill him? He knew he was now no use to his plans. He had thoughts of killing Anakin right there on the laval planet, so why did he keep him around? Learn more about your ad choices. Visit megaphone.fm/adchoices