It was spin stabilized. A stuck relay would have just created equal thrust all the way around the spin - ie the thrust would cancel out to zero. This design required thrusters that fired for very short intervals at a given delay after the earth sensor saw the earth, so the thrust would line up in the desired vector. In other words, no a simple malfunction cannot result in an orbit change.That said, it's an assumption in the article that the orbit change wasn't due to the cumulative effect of the normal gravitational perturbations the pull on all these vehicles. You'd need to dig up what orbit it was in 40 years ago and then calculate how the orbit would have drifted over those 40 yrs. Good luck.
IshKebab|1 year ago