[Hamuko]

But you're still having an engine failure when the engine is far away from anyone that could potentially start mending it.

[Jach]

Not an engine failure, but: "Debugging a program running on a $100M piece of hardware that is 100 million miles away is an interesting experience." http://www.flownet.com/gat/jpl-lisp.html

[zymhan]

"failure" does not necessarily imply it is permanently disabled. It just means the engine stopped working as expected at some point.

Obviously they restarted it after this failure so it was not a complete breakdown of the engine.