There’s no shortage of ways a satellite in low Earth orbit can fail during the course of its mission. Even in the best case scenario, the craft needs to survive bombardment by cosmic rays and tremendous temperature variations. To have even a chance of surviving the worst, such as a hardware fault or collision with a rogue piece of space garbage, it needs to be designed with robust redundancies which can keep everything running in the face of systemic damage. Of course, before any of that can even happen it will need to survive the wild ride to space; so add high-G loads and intense vibrations to the list of things which can kill your expensive bird.
After all the meticulous engineering and expense involved in putting a satellite into orbit, you might think it would get a hero’s welcome at the end of its mission. But in fact, it’s quite the opposite. The great irony is that after all the time and effort it takes to develop a spacecraft capable of surviving the rigors of spaceflight, in the end, its operators will more than likely command the craft to destroy itself by dipping its orbit down into the Earth’s atmosphere. The final act of a properly designed satellite will likely be to commit itself to the same fiery fate it had spent years or even decades avoiding.
You might be wondering how engineers design a spacecraft that is simultaneously robust enough to survive years in the space environment while at the same time remaining just fragile enough that it completely burns up during reentry. Up until fairly recently, the simple answer is that it wasn’t really something that was taken into account. But with falling launch prices promising to make space a lot busier in the next few years, the race is on to develop new technologies which will help make sure that a satellite is only intact for as long as it needs to be.