I'm confused by the title. There's no cat on Mars now as afaik NASA or anybody never stuffed one in a rover, and "through" implies continuity from this date. You mean "by" right? (I know you're trying to avoid the common "by" confusion, but this is definitionally the use case)

@Stralor "by" is confusing since it's often unclear whether it points to the start or end of the period. I have been using "through" to designate more clearly the end date, although I also take your point that it can be interpreted to mean "continuously through". Maybe I could say "sometime through X" to help make this clearer?

@StrayClimb isn't it funny that language is not adequate to express such a simple concept