People in the satellite industry are fond of automobile analogies. Like this one: Imagine that you buy a car and need it to run for 15 years, but you can’t change the oil or replace the alternator, let alone refuel it. That, they say, is the state of satellites. Once they’ve slipped the surly bonds of Earth, satellites pretty much just have to work, from the time they unfurl from their rocket fairing to the day they shut down for good.