Not necessarily. Any positive integer is greater than zero.

No one wants to be in situation like this (: https://www.youtube.com/watch?v=eP31lluUDWU&t=30

Where did you get that impression?

There were presumably computers there before on the other rovers. They either had Windows or a third OS or no OS according to the title.

Given the relatively slow CPUs and limited memory on those older rovers I would expect an embedded OS before Windows. Think QNX or VxWorks, not Windows NT.

VxWorks, specifically.

Some cyclic executives and such, too.

Perhaps when Russian or Chinese probes successfully land. They are both notorious for "borrowing" US software.